Achieving the highest efficiency from your heat pump requires attention to your radiators. When set correctly, the pump will run more smoothly, with less noise and reduced ‘short cycling,’ leading to greater comfort due to more even temperature control in your rooms.
I would also recommend setting your air source heat pump to ‘Weather Compensation‘ and adjusting your ‘Leaving Water Temperature’ (LWT) to a moderate setting, starting with 35 degrees Celsius for the central area of the ‘slope.’ More guidance on setting ‘LWT’ can be found elsewhere; this article focuses exclusively on the ‘Lockshield Valve’ setting.
The lockshield valve acts as a ‘flow regulator,’ controlling the amount of heat supplied from the flow pipe into the radiator. It should not be confused with the Thermostatic Radiator Valve (TRV) fitted at the other end of the radiator. The TRV serves as a temperature limiter, reducing the flow of heat only in extreme circumstances, such as solar gain heating up a room. Otherwise, the TRV should not restrict the flow.
To begin setting up the valves, ensure all valves (both lockshield and TRVs) are fully open. Ideally, this task should be performed in colder weather to simplify the procedure. At this point, the heat pump can be turned on. Then, feel each radiator to determine which is warming up the most—make a note if necessary.
The radiators, especially if newly installed, should have been sized according to room size and calculated heat losses, along with the desired room temperature. Starting with the radiator that warmed up the most, gradually close the lockshield valves from room to room. Initially, you might close the valve by two full turns, with final adjustments usually being half a turn or less from the fully closed position. Continue adjusting each lockshield on the next warmest radiator.
Allow time for the radiator temperatures to settle after each round of adjustment. If some radiators remain warmer than others, they should be the first to be closed further. This process, requiring multiple steps of adjustment, aims to restrict flow minimally until each radiator sufficiently heats the room, allowing the rest of the heat to flow to other radiators. For instance, we prefer a warm bathroom and keep the lockshield valve fully open on this radiator, which is the first fed from the secondary pump circuit, keeping the room very cosy.
Once the radiators provide proportionate amounts of heat for the rooms, allow the system to settle for about a day. Then, you might find some lockshield valves need a bit more tweaking. Proper adjustment takes time; although installers may make initial adjustments, fine-tuning to your comfort level is crucial.
Consider using thermometers in rooms and a temperature probe on radiators to gauge progress. An infrared handheld thermometer can also assist in assessing radiator temperatures and the efficacy of your adjustments.
If using a room thermostat, ensure it’s correctly set so the radiator in that area warms the room to, but not above, the set temperature. Setting the thermostat slightly higher than desired can initially help avoid frustration. Once radiators are balanced, return to the heat pump controls for any final adjustments.
TRVs should now be set to start shutting at approximately two degrees above the required room temperature. Under normal circumstances, TRVs will not disrupt the heating system but will activate if the room experiences solar gain or another heat source.
An efficient heat pump system prefers a constant load and resistance to water flow; while a lockshield valve provides consistency, a frequently adjusting TRV can reduce the system’s efficiency and increase operational costs.
*Note: Installers might set a low temperature heat pump to a leaving water temperature of 45 or even 50 degrees Celsius by default, even though a lower temperature is more efficient and still provides adequate heat.
Please note: While I am not an expert, plumber, or heat pump installer, I had an ASHP installed in 2023 and have carefully adjusted it after the initial commissioning. This required waiting for colder weather in December 2023 to fine-tune the lockshield valves and pump speed, achieving a COP well above 4 most of the time.
At installation, the smart controller was not available, so a basic thermostat was installed. Setting this thermostat a few degrees above the required temperature prevented frequent on/off cycling. After installing the smart controller, the temperature is maintained within 0.6 degrees of the desired level. I also repurposed a programmable TRV from a previous gas boiler system for the bedroom radiator, allowing for temperature adjustments at night, while the other nine radiators remain with TRVs fully open.
168 comments
@potatoman this article from Toodles should be very helpful in light of your recent request.
It is probably better to balance each radiator to achieve the desired room temperature, since the heating capacity of each radiator is unlikely to be directly matched to the heat loss of that particular room.
In a room with a physically smaller radiator the opening of the lockshield valve, and hence the flowrate through the radiator, will need to be greater to achieve the desired room temperature.
@derek-m Perhaps I should have worded my guide a little more precisely; when I said
‘Once the radiators provide proportionate amounts of heat for the rooms, allow the system to settle for about a day.’
What I was trying to indicate is that the heat from each radiator should reflect the heating needs of the rooms they are in. I suspect I am also guilty of thinking that the installers have done their survey thoroughly and accurately and that each radiator is very close to optimum capacity for the room it is fitted in. This of course may be fanciful – but isn’t this why we have the MCS so they can ensure the the installers do their job well? 😉
Tongue-in-Cheek, Toodles.
Unfortunately the type and size of heat emitters is determined by the proposed LWT, the available space and the room heat loss calculation, with the later being very subjective.
@derek-m I was probably very fortunate inasmuch that the eight radiators we needed to replace with greater capacity ones could all be fitted within the wall space we had available; by using K2’s, in most cases, they were no higher or longer than the ones we removed. I’m a bit of a ‘don’t mind what it looks like, will it do the job properly?’ type of person and so is my wife – we find pragmatism has great advantages! Regards, Carefree Toodles.😉
I have 12 loops that seemed not balanced at all when we bought our place. I bought 12 cheap LCD thermometers (20 Euros or so) with sensor on a wire and pasted these to the return flows. From there on, I started to adjust the flow in the loops in order to get them all to the same return temperature (with the bathroom loop a bit higher). My thinking was and is, that if the return temperatures are the same, the individual loops get enough energy supplied at the front end to get the same return water temperature. Maybe this also works for your radiators.
@Toodles I used a similar method to this last October and it works a treat. One thing I did find very helpful is a thermometer with a logging capability so you can see how each room behaves over a 24/7 timeframe, so fine tweaks can be made if necessary :-).
Logging thermometers are also great for getting to know your systems heating characteristics. For example, our house takes approx 4 – 5 hours to heat from 19.5 to 21 degrees so I know to set my smart thermostat to 13-30hrs to start heating to 21 degrees, so when the Wife sits down to watch the tele at 7pm she is not cold and I have not had to have the heatpump running all day to maintain 21 degrees (19.5 is our set back temp which is ok for the morning but not evening)
@technogeek Yes, I invested in 8 Govee logging thermometers (logging in the sense that they have Bluetooth capability and can send the log to my iPad for scrutiny.) Regards, Toodles.
I have just carried out your advice and I am within .5c of whatever the Rads I want at maximum in relation to room temoerature. How do determine WL ON THE FLOW C of Heat pump. presently 44c and has been 50c for some years.
Is it just a case of whether they reach the thermostat setting of what ever I am asking ?
@alfapat Well done, you are well underway but keep the LSV spanner/key handy for any tweaking you might wish to carry out later! Yes, see how the comfort level is for a day or two and if all rooms are still warm enough to your liking, then you might wish to lower the (what I know as leaving water temperature and I think you know as water law) another degree then wait and see. If you find that most rooms are still at your comfort level but perhaps one has become just a tad cool, you can tweak that LSV open a ‘nadgers’ [very technical term there!]. You can rinse and repeat until you find that the whole house is starting to drop slightly below your comfort level for all rooms. You then just take the LWT/WL up a degree again! Keep us informed how things go. The final stage may be to adjust any rooms that you wish cooler when there is solar gain or for ‘cooler at nightime’ such as a bedroom using a TRV. Regards, Toodles.
Thanks ! Head banging , haha !
Moving on a bit , I had all the rads where I wanted them at WL 44C. Rooms near the Movable room stat 22 . Smaller ones near 20c (Bedrooms) mainly.
In order to get the most economical flow temp I dropped the temp to 38c . The larger rooms were hardly reaching the spot by 1 degree. I also noticed the Kwh had risen on the smart meter .(I assume taking longer to get the room stat to agree and not reaching it) Overnight the two smaller rooms which were set to 2 degrees lower that Sta requirment were cold .
Clearly Wrong !
So I have put the flow temp back to 44c .
Incedently The room thermostat is always placed in the hall overnight where the open rad is stuated , I m not sure that this is the best place to place this , because if it last in line of flow returns then its going to take more Kwh to maintain the rest of the house temperatures.
Another trial to carry out and monitor.
There are several steps to getting the most efficient settings and you need to have faith to see them all through
1. Disable any external controls (TRVs and Thermostats) by turning them up to max
2. Ensure that any room influence function on your heat pump controller is disabled
3. Balance the rads for equal room temperature, or the required differential between room temperatures, dont worry about absolute temperature
4. Slowly turn down the WC curve until the house is just warm enough
You can do 2 and 3 together and you will need to iterate them over several days or up to a month to get it right. When you change (3) you need to allow time to stabilise, initially you can change by a degree or two every 6-12 hours but once you get close you need to change by a degree every 24 hours. When you change (2) you likelwise need to allow time to stabilise.
Before you do this you should read the section on WC in your manual, and make sure you understand which parameters to adjust and the principle of operation. If you dont or are not confident (they can be quite confusing) please ask.
Whilst you are going through this process, comparing kWh from one day to another is futile, as the conditions (outdoor temperature) change, which affect the consumption more than any tweaks you do (the exception is if we get a period of several days with very steady temperatures, which does happen occasionally, but never when you are doing this type of adjustment!). This means that you have to trust, maybe for several weeks, that lower flow temperature equals lower cost, until you have data over a range of conditions both before and after that enables you to make a genuine like for like comparison (which is still tricky). If you aren’t prepared to do this (which I can understand), then you cant possibly optimise your system. However if your flow temperature is 44C you will almost certainly pay about 12-18% more for your heating like for like than if its set at 38C.
Ah Ok , so when I think I have balanced rads at say to 22c then set room stat above by 2 degrees and if it makes the room temp too warm turn down lockshields to suit required 22c?
Do I leave flow at 44c or continue to try 38 and open cold rads a little more?
Our posts crossed so please read/re-read mine above also
In answer to the question, No, once rads are balanced leave them, and turn down the flow temperature/WC curve to get the right room temperature, with the room stat turned well up (I would say at least 5C above the desired temperature while you are doing the tweaking.
Your end point is
rads balanced but with the LSVs as open as possible consistent with being balanced (which means that at least one should be fully open)
flow temperature/WC curve just sufficient to get thee rooms to right temperature with no influence from external controls/trvs/thermostats
OK that complicates matters. What make is your heat pump? Can I presume that the TRVs are time-controlled, or are they basic TRVs?
I ask because some heat pumps have a time control that is ideal for Time of Use tarrifs like Cosy, others are more crude so you have to be a bit inventive (which is where your TRVs may yet come in).
if the room goes above desired 22 and the room stat programme is at 24 c Then adjust the WC Curve down
Water law.
No need to apologise, heating is complicated!
What exactly is the Danfoss programmed to do? Is it switching the heat pump on and off on a timer or if not that then what exactly.
Is there a reason you are not using the time programmer on the Samsung controller itself? Have you got the controller manual/can you post the exact controller model number?
Can you describe the timing you have set up for heating and DHW, is the heating (for example) on only during the Cosy cheap rates, or something else.
Sorry for the questions, Im just trying to understand what you are doing/attempting to do so I dont mislead you!
OK makes sense
How do you achieve the above, is it by switching off immediately before the boost periods or something else.
@jamespa Its never off , its either on a degree behind or at the same temp moving to next period , so I don’t really think its and advantage Aye those Heat Pump Tariffs. .
Sorry but I dont understand how you achieve this with the timer and manual TRVs. How do you tell it to be a degree behind, or is this just what it does because of random variations.
Unless you have a controller designed for the purpose (ie Homely at present) or one of the heat pumps with a more sophisticated inbuilt controller I think you are very likely right.
@jamespa s only what the room thermostat says when it moves from one of four periods , generally it doesnt always achieve this . TRV’s completely open now according to new advice. Wow thats been 8 yrs set up wrongly!
Now the room thermostat is set for 24 and finally the Kitchen is at 22c. So I will look at other rooms now.
OK I get you now, you are using the scheduled programmable temperature feature on the Drayton. This will switch thee heat pump on or off according to the programmed temperature and the measured temperature.
I will give some thought as to whether there is a neat way to make things work with Cosy, but a crude on/off function (which is what the Drayton does) is never a good start when it comes to heat pumps!
TBH if I had a Samusng heat pump and wanted to do this sort of thing I would probably get a Homely. However I dont, I have a Vaillant heat pump and a ‘simple’ 7hrs cheap tarrif at night, so just programming a nighttime ‘set forward’ (which the Vaillant controller can do) is the way forward. I haven’t bothered to do this as it happens but probably will when we get to the shoulder season.
I think your way forward is to keep TRVs open with balanced radiators, the programmer set to higher than you need 24×7 and the Water Law adjusted to get the temperature you want. In other words get it working stably with the Water Law being the only control and turned down as low as possible.
Once you have this working stably you could possibly to overlay a timed switch off in the couple of hours before the cosy cheap rate (and during the Cosy expensive rate). This will require you to jack the WL up a little, but hopefully not too much.
Can I just check that you are happy you know how to adjust the Water Law. I think its FSVs 2011, 2012, and either 2031, 2032 or 2021, 2022 depending on the value of FSV 2041. Is that what you have. Your controller is older than the current one (which is the one for which I have the manual)
Thanks James , hopefully getting there. By the way its a Danfoss not a Drayton , probably similar though.
Yes its 2021 , so I will put down the WL 1 degree and see how the room temps fare. Its kind of what I have been doing but Room thermostat has been tight to the mark . I wll see how we go.
Thanks for coming back on this. As you have probably gathered Im not a Samsung expert, just an amateur who has been studying this stuff for a couple of years in prep for my own heat pump, which I now have. Anything I say is offered in good faith, but in the end its your decision.
Please don’t do anything you aren’t comfortable with and please make a note of settings you change just in case something needs to be set back. The Samsung WL interface is, like many others, not a model of user friendliness, but you are on the right track adjusting 2021 while its cold. It should be possible to get it so that the house gets to temp at more or less any OAT, with the TRVs off and thermostat well above desired temp, without having to continually adjust the WL, but that will take some tweaking over a period of time.
Another thing worth mentioning about TRVs is that, if they happen to be shut when the unit does a defrost, they can deprive the unit of the hot water it needs to do the defrost. This is another good reason for setting them above the desired temperature. Of course you may have a buffer or volumiser that provides water for defrost also, although the former have their problems to say the least!
I saw somewhere else on this forum that Samsung basically doesnt allow you to schedule setbacks etc, but there is a ‘PV boost function’ that is adjustable and can be triggered by an external switch. This raises the FT by an adjustable amount while the switch is closed. You could potentially use the Danfoss timer to operate this during cheap rate periods, which is after all what you basically want (to force it to work harder during the cheap periods, so it can slow up during the expensive periods. I will try to find the thread and maybe make a connection in case someone else has already tried this.
Whatever you do Im pretty certain that starting from a position where the water law is basically optimised and the radiators balanced should be better. Really installers should do this but it takes time, time is money, so they opt for something that is quick but not as good. To overcome this the industry basically needs automatic radiator balancing and automatic water law optimisation both of which are beginning to emerge but not yet ready for prime time.
Please keep posting!
Yes there is a buffer tank , I ve been reading about them as not being essential , but will leave that for the moment . What do you mean by when you say that Samsung doesn’t allow scheduled setbacks please. PV’s being a Pressure Valve boost function. Flow setting is 43c at the moment and large rooms still very warm . I will leave till tomorrow. My conservatory is next to lounge and very cold with minimum opening on both rads in there , lounge a bit colder as a result, 1.3 degrees less than next room with door open . easy sorted with wood burner.
Its becoming clear (and installers are beginning to come clean on the matter) that buffer tanks are unnecessary in 95%+ of domestic situations. They come with a performance penalty of up to 15% or thereabouts, and make fault diagnosis difficult. Historically they have been fitted to prevent problems which otherwise cause call outs, but really they are masking them not preventing them. The more enlightened installers now admit this, but many are still clinging to the old ways. When @editor did a video on buffer tanks (on this site) he managed to find three installers who would join to advocate against buffer tanks but none of those he invited who advocate for would take part. That says it all!
2By buffer tank I mean a 3 or more usually 4 port tank (flow and return from heat pump, flow and return to heating system). 2 port volumisers are useful and have no performance penalty. These are fitted in series in either the flow or the return (arguments for both) not between flow and return. Turning a 4 port buffer tank into a 2 port volumiser is something worth considering.
Re “What do you mean by when you say that Samsung doesn’t allow scheduled setbacks please. PV’s being a Pressure Valve boost function. “
The Samsung controller does have a built in scheduling function, but it only triggers on/off operation of the heat pump using its internal temperature sensor (basically it does the same as your Danfoss but using its inbuilt sensor and timer function). What you really want is a function which, rather than switching the heat pump on and off, turns the flow temperature up or down according to the a schedule (to follow Cosy or for night time set back). Some heat pumps (Vaillant, Daikin, strangely not Mitsubishi) support this, others don’t. Samsung doesn’t.
PV in this case is photovoltaic – solar cells. The Samsung function boosts the flow temperature by an adjustable amount if a contact on the control board is closed. They call it a PV function, I suppose their idea is that if you have free electricity from PV you bump up the FT to take advantage. Yours is a relatively old model so might not have it, but if it does its a way that what you really want to take advantage of Cosy could potentially be achieved.
Re your lounge and conservatory obviously I dont know what you want to achieve but you know how to adjust the lockshields so you know what can be done. There is a limit to how much temperature difference you can get between two adjacent rooms and, counterintuitively, it is usually increases costs to leave rooms unheated (explanation and worked example on Heat geek site).
Keep going until you have the Water Law curve as low as it will go consistent with your house being warm enough. Thats the optimum efficiency point and the best starting point by far for any tweaks.
Hope that helps, I will post my thoughts on your ‘Cosy’ problem in a day or two.
@alfapat
I hope you are getting closer to the optimum adjustments.
Ive given some thought to how you can operate the optimised system with Cosy. I think there are 3 options, all starting from the situation where you have stable operation at your desired temperature on water law only as low as it can be (I will refer to this as ‘optimum’), with no external controls operative
1. Adjust the Water Law to a degree or so above the ‘optimum’. Then use the Danfoss more or less as you were previously, setting it to a bit higher than you want during the cheap periods and the temp you want during the expensive periods. Leave LSVs open
2. use the Danfoss to turn the heating off during all or part of the very expensive period, and the periods just after the cheap period. Adjust the Water Law up as necessary to get an acceptable temp (should need only a degree or so above the ‘optimum’ – a bit like the previous)
3. If your heat pump supports it, use the Danfoss or an external timer to set the PV Boost function during the cheap periods and just before the very expensive period. Turn off the heat pump during all or part of the the very expensive period and for an hour or so after the cheap period (you could use a second channel on the Danfoss or the heat pumps own scheduler to do this).
I think (3) is probably the best but depends on your heat pump supporting the PV boost function and its also definitely the most complex although at the same time in a way the ‘cleanest’. If you can and do decide to choose 3 I have some thoughts on how you might decide how many degrees to boost by and how long you should turn off by, basically using the ‘degree minute’ concept that at least two models of heat pump use as part of their control loop.
Im happy to contribute further on this if you want, its interesting to me to think about this problem as I have yet to program my heat pump to take advantage of the tarrif I have (EON Next Drive, essentially a variant on economy 7, giving me 7 hrs at 7p/unit overnight in return for ~10% uplift on the daytime rate- Great for charging an EV, averages out at less than the standard rate for a ‘constant load’ like a HP so overall not bad if you have an EV)
Morning James , Iam at 42c and just changed to 41c . The overall temperatures in the house are managing so far with the thermostat 2 degrees at every stage above the the normal 21/22c . The power usage is more levelled on the smart meter but has risen in the last 3 days of this adjustment . . So will see , it is -4c this morning but not seeing that graph till tomorrow.
I will think about your options but very unsre if they will work , especially the PV ONE Aas I dont have photovoltaic . I m sure that was your explanation of that abbreviation.
Ill work on getting WL down first.
You dont need actually need to have solar panels (photovoltaic) to use this option, you are just using a function of the Samsung (if yours has it) called photovoltaic, which in fact is just a contact that you can close to boost the flow temperature. I think this option, if it available to you, has the best chance of working, but is undoubtedly the most complex.
The bottom line here is that the heat pump controller, like most, is not designed for ‘tariff optimisation’, so whatever you do is a bit of a kludge. The only controller I know that is designed for tariff optimisation is Homely
There is actually another option for tariff optimisation – Havenwise. They now apparently support Samsung – take a look at their website. You need an internet interface to your heat pump but then its a service in the cloud (as is Homley at least in part).
Update.
So far on Wl settings for the last 24 hrs is at 41c.
I get it that looking at the smart meter recordings shouldnt be taken as read. The average temps in my area in the last 14 days have been around 5c duribg the day and 2c at night last three a little lower with frost . This could be an indication why my energy usage is still a little high despite dropping down WL from 45C to 41c . I can only relate this to HP adjusting things in order to give the same house temperatures .
The most recent night (morning of 23rd Jan) it was down to -5c outside so the total for 23rd was 79kw the 22nd which had WL SET at 42c the energy used was 82kw. I cant work out what is happening yet so I will leave at 41c
Foot note for the 17th Jan I only used 38kw and looking at temperatures for that day they were much the same 5c and 2c at night . WL was 44 or 45c around these dates ?
Head Banging!
Which is why I ignore individual daily readings completely and plot daily consumption Vs average oat over a period of weeks at least. The scatter on this is sufficient (at least in my case) to prove that looking at individual days is fruitless, and the only real approach that can be taken requires monitoring over several weeks to months.
The underlying problem, I think, is that houses have memory of 24 hours or more, so two identical days are in fact very different if the preceeding day or two was different. Also wind and solar gain matter.
How you deal with this is up to you if course.
Thanks James , just trying to get assurance thats all ,and trying my best within my capabilities.
I will stay static for a whille now.
Cheers!
Understood. Unfortunately, because we can’t control the environment, we all pretty much have to trust the specs and the physics. Fortunately all heat pumps have similar characteristics because they all depend on the same physics.
I have personally found that operating on weather compensation alone gives me a much better level of comfort than I ever had with my previous gas boiler and complicated controls, and I look to be on track to save perhaps 10% in operating cost. So far as I can tell, the physics is working for me as it should. Of course that’s just me and my system.
Hi @alfapat
I hope you are getting close to optimising your system.
There is a discussion on this thread https://renewableheatinghub.co.uk/forums/thermostats-trvs-pumps-valves/how-to-balance-radiators-the-role-of-the-lockshield-valve/paged/4#post-40825 about how to use a Samsung controller to effect a setback. Also some information about times setbacks using the Samsung controller alone, which is almost certainly the best way to do it if yours has the capability (it may be available only on more recent controllers, but perhaps firmware upgrade is a possibility)
@jamespa Thanks for your interest again . I thought I was , were I was down to 41c flow but ultimately although the temp in more consistant the energy needed doesnt seem to drop . Currently I have reverted to 44c where I got better results.
Quite interested in your link but it takes me back to the same page we are on, Ill look again
Incedently I am trying to find out if Homely is compatible with my 8 yr old pump but no answers yet
Here is the corrected url to the other thread https://renewableheatinghub.co.uk/forums/postid/41097
Without vastly more information about your system and the measurements that I care to ask (and likely than you care to give) I wont attempt to speculate on the explanation for your energy measurements, but the most important thing is that you are happy and warm.
I will have a look , thank you . Hey , warm , but not happy yet, don’t worry , keep the thoughts ongoing! 😏
Yeah , interesting , looks like Honely is the nearest to solving my system, if it’s compatible with Gen 5 .
Homely gets good reviews on this forum. The Samsung controller historically is a bit lacking in features (maybe the later ones are better) and homely fills the gap, albeit for some of its more advanced features requires a subscription. You have to fit the modbus interface to the Samsung I believe as well.
Help required here , I have had two calls from Homely and I still cannot find out whether Mod Bus is compatible with Gen 5 Samsung Heat pump.
Your Link to Grahams Heat pump Weather compensation video mentioned a Hand over book /manual for Samsung Gen5 . It seems impossible to find on Samsung’s site. Can anyone help.
Something not right yet , In the middlle days of Jan the average temperatures were 6c and 4c they are not that different now . In my quest to get the flow temp down I have been down from 45c to 41c . It did look like that the system struggled to keep things the same at that.
Seeing that I had smaller usage of energy , up to half that ofthe last 4 days I put the flow back up to 44c . Figures I am looking at are in the middle of January between 40 and 60 kwh and last 4 days 70kwh plus .
Something not right.
By ‘flow’ I presume you mean FSV parameter 2021. I am assuming you have left 2011 constant (at what value)
As I mentioned earlier, consumption over anything less than several days is pretty meaningless because the house has a memory of 24-48 hours (sometimes more), and consumption over several days is also meaningless because the conditions vary too much. Pretty much the only way to compare consumption is by plotting vs OAT over several weeks or more.
As I recall you put the FT back up because the consumption had gone up when you put it down, now you are finding that it goes up when you put it up! I fear the problem is that you are looking at the scatter on the figures rather than anything particularly meaningful. Obviously I cant be certain about this because there are features of your system, most notably the buffer, which might behave in an unexpected way, but in the absence of anything odd scatter on the figures is the most likely explanation.
Genuinely the only way I know to do this is to trust the science. Open up all the TRVs, set the thermostat as high as it will go so its constantly calling for heat, set 2012/2022 to a suitable pair of values for the warm end then adjust 2021 down until the house just keeps warm. Monitor over several weeks and tweak slightly up/down as necessary to get the right value. Check the daily but more importantly weekly COP to see if its sensible and address any obvious problems if any. If you are happy with the consumption enjoy!
If you arent prepared to trust the science I think your optimisation process is going to need at least a season, possibly two, so you can do a meaningful plot over a period of weeks for each change.
To give you and idea Here is a scatter diagram for my system over a period of 3 weeks in January. Its plotted vs degree-days, a slightly modified average OAT. Changing FT by 3C will result in 6-10% change in efficiency. The scatter, particularly in the interesting region where most of the points are, is probably double that indicating that more data would be needed to dig out of the noise the effect of changing the FT. No changes to the system were made during the period over which this data was collected.
Sorry I don’t understand the graph, and I don’t know how work out COP. What I can tell you are my Settings 2011 is -5c for Scotland
2012 is 15c ambient temp for wc
2021 is 44c Flow temp
2022 is 32c Flow temp in mild weather
2091 set at No 1 for run signal at terminal B22
Trv’s all open and lock shields appropriately set .
House definitely warm sitting around 21-22c
Attached is pipe arrangement on Heating tank
Sorry for not explaining the graph. Each point represents one day. The horizontal axis is the degree-days figure for the day (degree-days is a slightly modified average outdoor temperature, easily downloaded from the internet for a weather station near you). The vertical axis is power (in Wh) consumed during the day (24hrs). As you can see the power varies a lot from day to day even for the same number of degree days (average OAT). This variation will swamp any change due to flow temperature changes until you have more data.
The plumbing of your buffer tank is correct however a 10C drop is a lot, and makes me wonder if there is mixing going on in it. Not much you can do really, buffer tanks are a pain which are rarely actually needed, but all to frequently installed particularly 8 years ago.
COP is energy supplied to house /energy supplied to heat pump, should be in the region of 3-4 most days. Its basically a measure of the ‘free energy’ you get with a heat pump which is what makes them so efficient. I dont know if the Samsung controller tells you the figures (manual is unclear), some do some don’t, if it does it would be under ‘information’ or ‘energy’. If it doesnt tell you the figures you cant calculate it unless you measure the power externally, so you may be out of luck here.
Your FSVs are reasonable, you may want to drop 2022 a bit if you are too warm when it gets milder, otherwise concentrate on getting 2021 to the point where the house is the right temperature, which you appear to be close to.
Thank you for your patience and explaining my questions. There is -so much I understand , but may be over thinking , it’s just that my first month with Octopus on Cosy seems to be high(yes it’s cosy, make no mistake ) ! It has revealed a cost from 1st Jan to 27th is £509 , which If devide cost by KWh comes to .24pence so moving on I hope I can improve this . Onwards and downwards, cost wise!
Total kWh 2210 all on Cosy bar 1 day.
That sounds quite high, but of course I dont know much about your house or how much DHW you use.
My total January electricity consumption (minus 1 day) is 1076kWh and that includes charging my car (albeit not a lot for this). I have a 200sq m 1930s house solid wall (no cavity!) house with a couple of modest modern extensions, 300mm loft insulation, partial internal wall insulation (so some walls are still solid brick). The measured heat loss @-2 is about 7kW. By no means a passivhaus! Mind you we don’t use much hot water. I keep more or less the whole house at 20C 24*7.
@jamespa Yes just a bit !
Only hot DHW of significance is a small bath once a day. There are only two of us . Thanks
currently seeking info on Mod bus compatibility with Gen 5 . Fingers crossed!
Good luck on the modbus. I think you are in with a good chance, these units are based on aircon units used in commercial settings where modbus will likely be how the building management communicates.
Do you have the ability to measure the temperatures on the emitter side of the buffer tank, it would be useful to get a handle on these and in particular the difference between flow temp in from the HP and flow temp out to the emitters.
Yes I do, I have another set, I will place them shortly.
Incedently I notice from the sAMSUNG CONTROLLER that the oat side temp outside is 0.6c and two weather stations are saying -1.2c , so at least its not far out.
Attached earlier photos with HP and rads in circulation
Black probes being HP
Later without , when I came back to house all systems quiet
OK, the most interesting thing is the temperature drop across the buffer measured between flow from HP and flow to radiators. I dont think I can see that in the photo.
So , on the first two photos the Hp is delivering 43-5c and through to Rads its 37.4
2nd two photos its 36.6c to rads its 32 .8c remembering system is idle , yes it seems to be quite a difference on the first active pics.
I can take more when I see that the circulation is on ?
To the final question yes.
If the HP is delivering 43 and through to rads its 37, then you are losing about 12-20% in efficiency as a result of the buffer tank, which is going straight onto your electricity bill..
Repost when you have more info with the system running.
37.1C and 32.7 Emitters
All pumps , two on HP AND ONE CH pump are on setting three.
Attached is flow signal , not sure how you read that whether it’s the rh side of flow indicator or LH
@alfapat Your aim (when the system is running and has settled down after a few minutes) should be to match the temperature feeding out of the LLH to the emitters with that of the flow temperature into the LLH as closely as you are able, likewise the temperature of the return flow entering the LLH from the emitters should be as close to that of the return flow out of the LLH to the heat pump.
Too fast a flow from the secondary pump return to the LLH is likely to cause unwanted disturbance to the water in the LLH and cause mixing – this would cause the returned (cooler water from the emitters) to recirculate within the LLH rather than meekly following the direction of flow back to the heat pump. It is a balancing trick with compromises and a need for a little dose of pragmatism – but it will pay dividends! Regards, Toodles.
OK, so 41.9 in from heat pump, 37.1 out to rads, drop of 5C = 10-15% efficiency penalty. Not sure how the return to the heat pump is higher than the return from the rads though, this can be the case if the flow rate from the heat pump is higher than the flow rate to the emitters but in that case the expectation would be that flow temp to emitters is close to flo from HP.
In summary no idea what is going on (one of the reasons to dislike buffers!).
@jamespa Sounds to me as though the secondary pump may be running too fast and causing mixing in the LLH. You might care to try lowering the speed of that pump in stages and see if matters improve. Regards, Toodles.
Is it possible that , before I went up to the loft at that time , I noticed the HW tank symbol was on the controller. I did try to determine that by feeling where the valve lever was positioned in relation to each other , as I cant see them I wasnt sure . I can never remember which is closed or open . Perhaps one more visit is required.
Similar really, rads 5C lower than output of ASHP = 10-15% penalty. Difference of 2C on the return possibly a measurement error. I think @toodles might be right secondary may be running too fast. He suggests reducing the speed in that pump see if things improve. You are really looking for feed to rads close in temperature to feed from heat pump.
I wouldn’t change it too much though, deltaT across rads already 5, I wouldn’t go above say 8. Do you have any control over the speed of the pump on the HP side?
I think there is control, there is 1, 11,and 111, written on them, but which pump do I slow if its possible CH pump or HP OUTPUT OR return . Toodles you talk about secondary pump is that HP OUT PUT or CH.
To clarify has the HP classed as primary and inline secondary .
Being dumb again !
@alfapat Not at all dumb, much better to ask before jumping to conclusions. The primary pump will be the one in or attached directly to the output of the heat pump flow pipe. The pump that sits in line with the output from you LLH is the secondary pump and it is this one that you should adjust. Were it running too fast for your set up, it would possibly cause the water flow in the LLH to mix due to turbulence. What you are aiming to do is ensure that the flow through the LLH is as smooth and even as possible so that the stream of water is from the heat pump flow to the emitters and then from the return to the LLH and then to the heat pump return with as little mixing as possible. (Almost as though it was just a straight pipe from flow to emitters and another one from return from emitters to the heat pump.) So, in summary, try slowing the secondary pump down and observe if the difference in temperatures narrows; take it in small stages and pause to see the result. Regards, Toodles.
Thank you , I will give it a go , so I am looking at the pump returning the flow to the HP .
Just to be clear , I would have thought that turbulance is caused by to much flow into an area like the the tank (which I believe you shorten as LLH) and not getting out as quickly as it can , but by slowing the process down would make it worse.
On the other hand I suppose slowing down the output and not return would take the advantage of building heat from the HP would be lost and everything being held up in the tank and not circulate . Hmm
I will give it a go anyway
@alfapat LLH (Low Loss Header) or you may have a similar device (a buffer tank) basically has the same ports and is in line with the flow from your heat pump. The heat pump primary pump sends the energy in the form of hot water around the circuit so that it flows to the emitters. The secondary pump is there to ensure that the energy is carried around the system once it leaves the LLH or buffer.
The water does not normally need to run a grand prix race but just circulates (relatively) gently to do its’ job. When the water is flowing through the LLH, it may just flow as required or if pushed too hard, will look for other ways to find freedom and escape! This will cause the turbulence (or as it is sometimes referred to as, distortion.
The flow from the heat pump ideally should go straight on to the emitters without being mixed with the return flow at all – but in this less than ideal circuit, some of the water will be diluted with the colder return flow. The balance you are aiming to create allows for the flow to get to the emitters but still have sufficient oomph to keep the return flow to the heat pump after passing through the LLH or buffer on the return journey. More speed or pressure will cause more mixing and lower overall efficiency. Regards, Toodles.
So I lowered the return flow and will monitor temperature . In the first 1mn I noticed the the flow return up .2c from 31.1 o .31.3!!
12 hours later and after slowing return pump down I get 36.9C and 28.6c HP and for CH 31.5C and 26.5c
@alfapat Sorry, I am a little confused as to which is what here. Might you possibly express the temperatures as flow from HP, flow out of LLH, return to LLH and return from LLH to HP please? We can gain a clearer idea of which is what then I think. Regards, Toodles.
@alfapat It looks to me as though there is either a lot of mixing of flow and return going on in the LLH or the sensors are all over the place. Have you ‘calibrated’ the sensors? By that I mean bundling all the sensors together and noted any differences in their readings. My four were different but a pair were a whole degree different to the other two – the two ‘pairs’ were noted and as the other differences were within 0.1 degree, I have just made mental allowance for the degree difference in readings. It doesn’t matter which is the nearer to correct temperature – we are only looking at the relative differences here. Regards, `toodles.
So stick them all to same heat source and see what they say?
@alfapat Yes, bind all four probes in a bunch, perhaps with a rubber band around them all so they are in close contact to ensure they are all seeing the same conditions. If the probes are waterproof, they could then be suspended in a glass or bowl of water and then observe the differences once they have settled down. I had the additional complication that 3 of the 4 had less then fresh button cells – in fact 2 died during this testing phase so I had to delay until fresh supplies were purchased, (I note that Brendon Uys {@heacol} is discussing distortion as it pertains to LLH and Buffers in another thread,[‘4 Port Buffer Tank Connections’ that you may care to read too] in your ‘spare moments’ 😉) Regards, Toodles.
Yes Ill do that.
Let me pose the question , forgive me if Im wrong but if a pump is delivering into a tank and the outlet is at the same level as in position , then say it is at 20l a minute and the outlet is recieving this and is at a figure of 15litres then that would cause turbulence , but if the exit is at 22 /lmn then it comes to be less turbulence. It seems to me that I should swap flows vice versa , like output from HP lower than than feed to LLH then return higher to HP . Am I wrong?
@alfapat The general consensus is that the secondary circuit should run at a slightly lower rate thean the primary. This is a matter that @heacol is far better to advise you on than I might. Regards, Toodles.
@toodles Ok Thanks , meantime I will go to the loft and extract the probesand test them.
This is just a pickle!
@toodles to my very basic understanding, and again @heacol is the best person to confirm this, with a buffer tank in the middle, the primary and secondary circuits should have matched up flow rates to avoid distortion in the buffer.
Buffer tanks can work if you are lucky, I am yet to make one work successfully 100% of the time and I do not gamble with other peoples money, it is unethical.
@heacol I recall a considerable amount of discussion (relating to LLH’s mainly rather than buffer tanks as such though) some while back and one of the threads is:
https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/low-loss-header-is-losing-1-5c-from-flow-temperature/paged/2
There were other threads along similar lines and this is where I felt a ‘consensus’ was evident. If I am wrong, my apologies to all for leading you astray!
In my own case, I have a Daikin heat pump and I THINK that the primary pump adjusts automatically to maintain a set Delta T. Having an LLH in circuit, I have attempted to adjust the speed of the Wilo Pico pump (secondary pump) to minimise temperature difference between flow to LLH and flow out of LLH to the Wilo pump. Similarly, I have attempted a similar arrangement for the return to the LLH in and the out returning to the heat pump. I find that at times, the balance is within 0.3 degrees C but at other times, this may be as much as a degree of difference!! I think both pumps have a degree of dynamic control and that this is the reason for the apparent variation. Regards, Toodles.
@toodles I am totally against any form of system separation in a domestic environment and most commercial environments. I have installations with over 400 Kw in capacity and 9 heat pumps, all connected to a single flow and return, the separation/buffer arguments just do not stack up. Any form of separation makes things complicated and can cause significant performance losses. In my opinion, simplicity is always best.
If only others took the same approach we would see far, far fewer posts on this forum (and others) complaining about poor performance, and indeed far fewer posts complaining about other problems, the origin of which it is difficult to diagnose due to the presence of system separation.
We would probably see an increase in posts about low flow errors which otherwise are masked by the buffer. But the underlying causes in many cases need to be fixed, so in many ways that’s a good thing.
There is probably a business to be made from removing buffer tanks!
Sending for more probes , one is dodgy! Its sending me a higher temp on return to LLH than the feed to rads.
@alfapat I think there is a line from the Engineer on Star Trek that to cover that! 😦 Toodles.
Maybe mine as well !As in Buffer remove.
New sensor in place and so to correct the flow indications between from HP to buffer /Tank there is a difference of 2.6 c. That is to say HP to tank and tank to emitters . Emitters return is 33.7 and Buffer/Tank to HP 36c
Too much or ?
Not great, 5C = 10-15% efficiency loss (much more according to @heacol). TBH I cant understand whats going on in the buffer, its like there is no stratification at all and you have essentially a vessel sitting there at ~36C, with both outputs therefore at this temperature. Im beginning to wonder if its correctly plumbed but cant remember if we have already discussed this. Is it worth posting (or reminding us of) some pictures indicating flow/return to/from HP/rads. Also please can you remind me how the pumps either side are controlled and in particular can you get to a situation where one is on and the other off for a reasonable period of time (thus, inevitably, ‘stirring’ the tank)?
Here is the layout as much as I can.
Above left Ch pipes
Above zone valves.
Above right flow from HP.Above showing Ch pump on white pipes. If there is anything more specific I will take more.
no diagram!
Ha should I have , sadly not, Only the one I have drawn.
What would you like to see , and I can give you some information
Sorry I didn’t spot the pictures above.
Buffer tank looks very squat (which would explain lots). How high is it and what is the vertical distance between the ports.
Also what capacity is your heat pump and what diameter the pipes to the buffer tank.
@jamespa Will check James
Tank Capacity is 200l Pipes are 28mm Copper , not sure if you want the size of CH pipes I can check but definitely smaller of course either 24 or 21mm . Tank vertical distance is 65cm for HP pipes and 67 cm roughly for CH.
Thanks
Sadly with a 60cm high tank I think the chances of maintaining stratification (IE a temperature gradient from top to bottom, which is what you want) is negligible, which accounts for the almost complete mixing you observe with the temp sensors. Whilst the tank remains you are stuck with the 5C drop across it. I suspect that adjusting flow rates will make a marginal difference at best to this.
@jamespa Thanks , looks like I should remove it then . Question I have , if the HP pipes are 28mm and they are directly connected to the smaller CH pipes , does that not cause a problem , except if you had control of the pump speeds ?
If you remove the buffer you will also need to remove the secondary pump.
Re your concern, it depends. Some further detail will help determine.
OK James,
Ill see if I can answer your questions. the heat pump is 16kh , would the loss be on the commissioning ? The original commission had another HP alongside 9kw., but this was removed when another company accepted to take over the whole thing when the original installers were liquidated. So I only have there proposal.
System is placed in a large loft and CH pipes travel down to one floor , they start plastic but down to copper .
DT?
OK.
16kW is not compatible with 22mm pipework, and barely compatible with 28mm at a typical design DT across the radiators of 5C
That said 16kW may well be an overestimate (or even a gross overestimate) of your requirement. Its quite plausible that this to be the case – over sizing is common even now and back when yours was installed probably endemic. Two relatively recent ‘professional’ 3hr surveys for my house came out at 16kW, its actually 7kW or possibly a bit less.
Essentially, to omit the buffer tank and second pump, you need to satisfy the conditions that
with your existing pipework (or pipework you can reasonably replace)
I think the summary is, this needs a study that is more in depth than that which I can realistically do on this forum. Essentially it needs a partial re-design of your system but wherever possible using the same components. A randomly picked heat pump installer is unlikely to be capable of that (because they would be too reliant on ‘rules’), maybe a ‘heat geek’ qualified one might. Its also possible that a commercial heating designer might because they should be used to actually doing calculations (some aren’t, as I discovered to my cost in a work-related project).. Alternatively you need someone who can do the analysis ‘from first principles’. Its not fundamentally difficult, but it needs a visit and some thinking which is not entirely ‘in the box’.
Unless you are prepared either to do this yourself or to pay someone to do this, you are probably stuck with the buffer.
There is one more option, which is that you plumb switchable bypasses (ideally such that the buffer becomes a 2 port volumiser) and ‘suck it and see’. If you fancied a couple of days of plumbing in the summer season that would be good prep for next year!
Otherwise its a case of living with a 10-15% penalty doe to the buffer, which may or may not be necessary unless you are prepared to replumb your central heating system.
Im sorry to be the bringer of bad news, maybe others have an alternative suggestion.
This is depressing , I have spent now a couple of months now trying to sort out a solution or some sort of headway on this forum to readdress the biggest investment (apart from buying the house) and sorting this Air source running cost. I feel absolutely useless as what to do now apart from trying something like Homely. I have now spent £25000 on a heating system that simply is pants! To put very lightly.
If you were willing to supply more info I could probably give you a good idea if just scrapping the buffer will work.
Some of this is in the certificate you posted above. and where it is I have pasted in the values for you to check I understand correctly. If you could advise the rest, or at least most of it, I can give you some more pointers
With 13kW demand (If thats real – which it may not be) I really cant see how a single 22mm primary feed to/from rads will work at the typical 5C deltaT that heat pumps operate at. So if that is what the demand is, and if there is really only a single 22mm feed, then the buffer is a necessary element of the design to allow the secondary to operate at a larger delta T flow -> return to the primary. But if this is the case then you should measure this on your thermometers which so far I haven’t seen.
More detail may help point you in the right direction or, if you are lucky, confirm that 13.5kW is a gross overestimate and you can in fact get away with 22mm.
Insulation increased before installation to Loft at 300mm. Insulation below floor 2022 170mm
Installation 2015
one pump 16kw , the other sold after recommisioning. Sub section 4.1 (v1) on THE MCS Certificate shown above is Heat Loss 13.48kw
Distance from Buffer to eaves in loft approx. 3m then a drop to outside ground 2.70m.
Timber buit House on Dwarf wall . Insulaation on outer interrnal room wallsapprox 1inch polystyrene silver backed stuff!
Total area 199sq m
28mm hp piping to split joint between DHW and Buffer joints 30mm
Oil burner before with Wood stove on zone valves (amature set up) Unknown running cost as only moved in 2015
Pics to follow easier on phone
transfer.System temps shown passive no circ required.
and layout to eaves. I am told that TRV ‘s would be installed along with buffer and controlled by Danfoss thermostat shown earlier in threads. As the TRV’s are fully open now and the system changed using lock shields
With your insulation upgrades its quite possible that you may be able to dispense with the buffer without changing the pipework. Can you clarify the following (which I cant work out from your photos).
The picture attached shows the Ch pipes top and bottom, (never mind the expansion vessel that is scrap ) the pies come out and in about 15” in copper 22mm then take a right turn in 22mm plastic for 9 feet another turn for a couple of feet into copper 28mm and drop down from the loft and under the floor. I think all rads are on 15mm . I’ll get temp at evening and record flow and return and Oat At present late afternoon 11c , flow temps 27c and 39 out CH Controller says house 21.4 , 9.6 outside temp, circ 39.7, DHW 48.5.
So heating pipes go from 22 copper to 22 plastic to 28 copper? What a lazy sod of a plumber who fitted the heat pump
Would it be practical to replace the 22mm with 28. If so there is a high probability it will work without buffer and secondary. Better still keep buffer repurposed as a 2 port volumiser.
It might work without upgrading the pipework, but no real way to tell other than trying it. Personally I would be tempted just to plumb a switchable bypass to the buffer tank and secondary pump and see what happens. Given the plastic push fit connectors (see earlier comment about plumber) that might not be so difficult.
@jamespa Perfectly possible re the pipes from the Buffer , worth trying first?
Switchable by pass (whatever that is) as well as changing pipes ?
Update
Midnight
Samsung Controller readings are House temp 22.3 outside -0.3 33.4 rising as bath run , water 23.5 . Readings in Loft Flow out to CH 37.9c back in 24.4c From Hp 42.8 Return to Hp just before zone valves changed to DHW Replenish as bath run 34.9c Hope that helps ! Oh weather Station says -1.3 Indoor 22.9c to 23.3c indoors
Sorry thats lots of numbers, but no clear explanation what they are measuring.
What is needed is the temperatures of flow to and return from the radiators (ie the deltaT across the radiators) when its cold outside and the central heating only is working.
Why – because if its much greater than 5C it indicates that the secondary is running at a higher deltaT than you would normally run a heat pump at, which may indicate that flow in the secondary will be a problem if you remove the buffer. On the other hand if you previously turned down the speed of the secondary pump it may just be down to this so if you did previously turn down the speed of the secondary pump please say so (with the figures) or turn it back up again for the experiment.
Attached sketches of switchable bypasses for the secondary pump and buffer tank. When pump is bypassed it also needs to be turned off. What you need to determine is, with the secondary pump/buffer out of the loop, do you get sufficient flow. If you do you are good to go, if you dont then there is a problem which may or may not be solved by swapping out the lengths of 22mm. The flow requirement for the heat pump will be given in the manual and the heat pump itself will almost certainly measure and report it somewhere in the UI and also complain if it is insufficient.
Samsung Controller readings are House temp 22.3 outside -0.3 33.4 rising as bath run , water 23.5 . Readings in Loft Flow out to CH 37.9c back in 24.4c From Hp 42.8 Return to Hp just before zone valves changed to DHW Replenish as bath run 34.9c Hope that helps ! Oh weather Station says -1.3 Indoor 22.9c to 23.3c indoors
The Samsung controller has information on the panel I thought might be relevent to mention so it said that the House temp. was 22.3c
The outside temp at that time on the controller said -0.3c
Circulation temp was 34.9c slightly lower than normal , but a bath had just been run. Hence the DHW was 23.5c
I read the circulation temperatures of the CH in the loft before the zone valve changed to DHW.
So the flow out to the CH system was 37.9c , the return temperature was 24.4c (quite low return)?
The speed was turned down at those figures above.
The flow temp. from Heat pump was 42.8c
The flow temp. returning to the HP was 34.9c.
The House temperature on a separate Thermometer was 23c.
I hope I have explained that better!
I will try and find HP pump flow speed , its not in manual.
Perhaps the information is on here, it mentions on the comissioning sheet the circ speed should be three on the pumps , it has been on that upto a week ago , main out put is three , the others are two .
On the grounds that turning the pump speed down didnt help I would put it back up again. Slow flow = higher deltaT across radiators = higher FT needed = lower efficiency. If turning it down had helped with buffer mixing then it might have been worthwhile, now we know that this is not the case best to turn it up again. Once you do can you remeasure the temps (flow to/from radiators). Explanation now much better, high deltaT across rads a concern but lets see what reinstating the pump speed does.
@jamespa I have been up to change the CH pump and return pump back to No.3 and taken a note of flow temps circulating the CH . I will take another read later
OAT -2C
Output to RADS 37.9C Return 24.4c
Flow from HP 42.8Cc Return to HP 34.9c
Been 2hrs since DHW has been used , only a small amount used and sitting at 47.06 c , should be 50c set for programme , I have been in 20mns and DHW 47,3 , no efficiency there , no taps used?
Once The water heating is off , I will get CH flows.
So checked again on Samsunf controller The water temp is set for 52c but never reaches that . Zone valve now switched off DHW back to heating and water at 48,6 Flow on controller at circ 41.5c
Flow to and from Rads now at 33.7 and Return 26.3c
So deltaT across rad circuit = 37.9-24.4 = 13.5C. ~5C is what we are looking for. So Im expecting the return from rads to be more like 32C than 24C
Either something is wrong with that measurement or you have a real problem (blockage) in your secondary circuit which will be costing you a further 15% penalty on top of the 15% penalty caused by the buffer tank.
Are you sure that the secondary is fully open except for any adjustments to LSVs to balance the radiators (with at least one LSV fully open)?
Are you sure about the measurement, particularly the one measuring 24.4?
Are you sure you took this measurement when the secondary pump was on and the system hadn’t just come out of a defrost?
Are you sure that the 22mm becomes 28mm after a few metres?
This is, unfortunately, another reason to hate buffers, they deprive you of the tools to diagnose faults easily.
please respond with any other information/measurements you have which might help unravel this.
I will check return flow temp 24.4.
System not circulating at the moment to measure properly , but will once it does. At present its 30c out and 22.8 return on CH
Not sure on whether it was defrosting late last night at the time of measurement, will catch up on that.
OK thats a bit more reasonable albeit higher than might be expected, and gives some hope, but by no means certainty, that bypassing the buffer and secondary pump might work.
I think its now down to you to decide whether to try it or not. If you do decide to try it be prepared also to swap out the 22mm for 28 and also be prepared to reverse out the bypasses (if you fit shut off valves its just a case of shutting/opening the shut off valves, which is why I suggested them). Perhaps something to leave until its warmer, but not so warm you cant test it! The key test will be flow rate which your controller should tell you.
the difference between 47 and 50 is small, perhaps the tank cant reach 50 on the heat pump alone. Many only heat DHW to 48. Unless its actually causing a problem I suggest to focus on one thing at a time.
Ok James , thank you for your thoughts there . The option to bypass being the the drawing that you sketched ? perfectly willing to change 22 to 28 mm , doesn’t make sense as it is .
Big question is finding someone with your knowledge up here .
please can you set out the resolve I need to apply to a Heating engineer in that I can explain a work around to sorting this .
Yes the bypass is as I sketched, although I should sound the note of caution that, as I don’t have a full system diagram, there may be something else that needs to be taken into account.
Its a very simple plumbing job that needs absolutely no knowledge of heat pumps whatsoever. I try just explaining to a local plumber that you have been advised to rig up a switchable bypass to the buffer tank and secondary pump, so you can test which works best, and all you are asking him (or her) to do is the plumbing. With a bit of luck someone will say yes. If you cant persuade anyone to do it then your only option is DiY. As I say upthread the key thing to check once its done is the flow rate seen by your heat pump which should be somewhere in the UI, probably under info. If it isn’t then the key thing to check is that the heat pump doesn’t ‘complain’ about low flow rate.
With a bit of luck flow rate will be fine and you can turn down the WC by about 5C. If it isn’t you have lost the cost of the plumbing work. I cant honestly see a way to be sure without trying it.
@jamespa Thanks , once again! Is that not the flow rate shown on that page I posted, 16L/pm or is that a completely different thing you’re talking about, and what is the WC please. Weather compensation?
Its the actual flow rate, after you have bypassed the buffer/pump, that you are interested in. Your controller should have a read out and I would make a note of the current value.
WC = Weather compensation, what Samsung call water law.
@jamespa Hi James , I thought I would draw out what is the best I can do , my system arrangement to help understand what I have in place , if you want any thing that’s missing ,I can add , but it’s fairly basic. I hope it clears any doubts you may have in my set up.
Nice drawing, Im glad you did it.
have you really got two pumps in the primary, one on the feed one on the return. If so are they (and the pump on the secondary) all the same model?
I guess its silly of me to ask why because you have no way of knowing. Are either of them controlled by the heat pump and if not do you know if anything controls them or do they run continuously?
Yes , I have three circulating pumps , one from HP and one circulating and one return, They do go on and off but I cant tell in what sequence , At the moment it must be the oat or something as the TRv ;s are open fully and the Thermostat is above room require ments by 0ne degfree and never get there as advised.
So costs are high as I see it but comfortable heat in house .
@alfapat are they all the same model?
Is there any way you can tell what they are wired to?
The answers might affect the strategy for buffer removal.
Yes all the same model , with a selectable speed as mentioned before , selectable manually by a button , but not sure if controlled otherwise. I will follow if I can the wiring . As far as I can see , they all go to the Samsung box nearby.
The picture shown is the Ch pump , I will check as the picture shows all three lights on the pump speed , usually it shows only the speed selected.
Ok. I’m going to seek some advice on operating two pumps in series, which effectively you already have but when the buffer is removed becomes more directly connected. I suspect it’s best to bypass 2 pumps, on in the secondary and one in the primary, but let me first ask someone who may have experience of this.
Please try to trace what they are wired to.
@jamespa Pumps in series are not a problem, the flow rate on the pump is approximately the same and the head is about 70% more (not double).
@alfapat, your problem is flow and distortion caused by incorrectly scized pumps, lack of knowlage and poor design. If your house is warm, but your bills are high, simply removing the buffer tank and secondry pump (with some re-programming) you will have significant savings, possibly as much as 40%.
@heacol Thanks for the info on pumps and head (Im presuming when you say pumps in parallel you also include in series – as here); with that and the measurements @alfapat has already done I think we can be pretty confident he has enough pump head to push through his heating system at sufficient rate. I have seen it said that pumps in series are a problem but never understood how that could be the case (unless grossly mismatched so one is sucking at the other).
I believe @alfapat is already convinced to remove/bypass the buffer tank and secondary pump and thanks for confirming my suspicions here. I’m hoping he is going to trace the wiring to the pumps to find out what is controlling them, so we can work out what reprogramming might be necessary (other than the obvious of adjusting the WC curve down and pocketing the money saved!).
@jamespa (Im presumeing when you say pumps in parallel you also include in series – as here); you are correct and I have corrected my post. Mismatched pumps in series, are not a problem as long as there is flow at the duty point. Grossly mismatched would be a problem, but anyone who knows anything about pumping, would not do that (however it is common in this country).
I would suspect the secondary pump (after the buffer) is controlled by a third-party thermostat which also controls the heat pump through an input. The primary pumps will most likely be controlled by the heat pump. To get this to work, significant programming alterations need to be made. It is not just as simple as removing the buffer, second pump and thermostat.
@heacol and thanks James, I will look at all the labelling to see if any of the pumps differ in Spec. I already have two spare ones chucked aside in the loft , discarded when th 9 kw unit was remeoved ! I will trace the wiring as well
Yes, the house is a lot warmer and consistant ,with changing to balancing with lockshields, but using up a lot mor kw I fear . Over the last 7 days with oat ranging between -1c to 5c roughly its averaged at 77.7kw/h.
Thanks. Im guessing the same. I am not a Samusng expert (or indeed a heat pump expert) but Im hoping the changes needed, to get it running open loop on pure WC as a starting point (which it is more or less currently, albeit with a buffer) are in FSV20xx only plus whacking the third party thermostat up to max. The plan is to make the plumbing switchable so it can be restored to current config. Its a very old installation so warranty isn’t an issue, just function.
Incidentally its clear (at least to me) from this forum that there is a need for trusted, intelligent, knowledgeable people to provide a ‘diagnose and fix’ service for heat pump installations. Whether anyone would be prepared to pay the rates that they would demand is of course another matter!
@jamespa “Whether anyone would be prepared to pay the rates that they would demand is of course another matter!", they are not, we have sorted a lot of installations and have never made any money on them. It is an expensive game, diagnosing and sorting cowboy jobs.
es, the house is a lot warmer and consistant ,with changing to balancing with lockshields, but using up a lot mor kw I fear . Over the last 7 days with oat ranging between -1c to 5c roughly its averaged at 77.7kw/h. (I might add thats the total House elect)
Reading back about mismatched pumping , it doesnt help when one pump, the CH, is either sucking on 22mm or pumping it to 28mm.
Glad its warmer and more particularly more consistent. Be careful about concluding its costing more though, the last few days were quite a lot colder than the previous few and any measurement over less than a few weeks is inevitably very much subject to ‘noise’. That’s one of the problems with this stuff, doing experiments on consumption is fraught with difficulty because we have no control of the outside conditions. With greater stability you might well find you can edge the water law/WC curve down a degree or so still and still be comfortable which will help.
That buffer tank needs to go IMHO, its just a case of when! If you want to do this then in prep you need to
of course its all your choice.
@jamespa so both feeds to the HP line pumps go to the Samsung controller and the Circulation goes to this box in pic attached All pumps are the same spec .
Other than opening up the Samsung junction, , including the two white boxes on the floor if it helps , then I assume it’s wired correctly.
The two black wires from white boxes go to Zone valves
@jamespa so both feeds to the HP line pumps go to the Samsung controller and the Circulation goes to this box in pic attached All pumps are the same spec .
Other than opening up the Samsung junction, , including the two white boxes on the floor if it helps , then I assume it’s wired correctly.
so both feeds to the HP line pumps go to the Samsung controller and the Circulation goes to this box in pic attached All pumps are the same spec .
Yes James , that is correct.
To answer some of the points made by the contributors about the wiring , it does seem quite a mess.
About two years ago I tried my luck to get a local sparky working for an Ashp plumber , they spent all morning scratching their heads then came with an answer that the sensor for DHW tank was faulty. When I bought it , I measured the resistance on it and it was the same reading as the original/
I then found a young guy working from Inverness and he found all the wiring in the wrong terminals on the board. He mostly swapped the way it was wired on the inside of the lid to be fair using the originals and did label them for his own use,
If it helps , and perhaps not at this distance I can do further labelling.
I really cant find anyone else that would confirm the present set up , unless Mars can find someone to recommend locally
My strong gut feel is that, if you bypass the pump in the secondary, turn the thermostat up to full, bypass the buffer, it will work. Basically the heat pump will then have a continual call for heat which it will supply according to its own algorithms and WC. It wont really ‘see’ much difference. Since we know that one pump is sufficient for your secondary, its aapretty sure bet that the remaining two pumps will be sufficient. Very likely you could delete one leaving only one pump. It would however be best first to check the 2xxx FSVs.
If you go down this route you could try it, then tidy up the cabling (or not) depending on how it works (or not).
If it were my system I would do this, but not in the depths of winter.
Done bit of labelling and those white wires are four core but not all used.
Sounds like the HP side pumps are controlled by the HP.
By zone valves you mean the two valves which either switch to CH or DHW?
The circuit diagram doesn’t match the connection styles/positions on the circuit board.
I’m particularly anxious about the thin white wires which might be carrying 240v AC to a “Booster Heater".
That 20A fuse might be on-board.
I don’t know if it’s replaceable or soldered in.
A fuse must protect the wire, and should be of a lower current rating.
I’m unsure what’s happening in this area of the control PCB, but I’d be investigating further.
I think those wires might be sensor connections possibly to the points marked wht 1 2 on the diagram
So where are the connections for the “Booster Heater"?
I don’t see any thick wires arriving at that point on the board.
Is that terminal block absent in this version, perhaps?
I think @alfapat needs to start labelling cables where they enter the controller box.
The outer sheath of mains cables can be written on with pencil or ball-tip.
You don’t need a special marker.
I tend to use a bit of white PVC tape when first pulling cables through.
Once they’re in their connection box, I switch to a label around the outer cable,
which I hold in place with clear heat-shrink sleeving
On Alphapat’s controller box I don’t like:
I wouldn’t allow an electrician to connect into my consumer units like that.
@transparent I dont disagree in principle but … in the real world where time is money and the customer doesnt want to pay the latter
I watched my heat pump installer work on his own for a week, arriving at 8am and leaving at 9pm on one night and 7pm on another, with no break at all during the day. I can forgive some things!
there may not be a booster heater fitted, they are not used that often to the best of my knowledge.
I think what makes this installation the more confusing is that the installer has only used three-core (lighting flex) for everything.
When he’s needed three cores plus earth for the “3-way valve", he’s used two separate cables.
The two blues are connected to different Neutral points,
one of the browns is the live supply via an on-board fuse
whilst the other is a switched-live.
Both browns are outputs from the controller board.
Without any labels it’s too easy to get the browns the wrong way around.
And there is a strain-relief position for the un-clamped cable,
but he just didn’t fit a cable tie through it. 😣
I think the Booster Heater port is for the DHW immersion heater.
There’s no other terminal labelled for that,
and it’s the only output which we would expect to have a 20A fuse indicated on the schematic.
I might do a bit of labelling, but found these diagrams . The field settings shown are the only ones I can relate to and using .
Sorry think I have two the same , don’t seem to be able to edit!
@alfapat
OK, thats very helpfu. If you just record your values for the FSVs in the first picture that should be fine. Most will probably be as per the picture.
That is the one to be bypassed in the first instance. You may also be able to remove the pump on flow or return, but I strongly suggest to proceed one step at a time.
Not sure what you are asking, in what context?
Good.
Noted, please can you check the other 20xx FSVs and post them just in case there are any surprises!
@jamespa
Posted by: @alfapat
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Just to be clear we are looking at the difference between HP output and CH OUTPUT OR RETURN? Sorry should know by now.
The flow temp. from the Hp compared to the flow feeding the CH.
The min. Requirement being 1c-2c obviously by time it’s being round the rads it’s less . The other FsV’s have not been Changed , so 2011 is set for -5c
2012 for High ambient Weather comp. +15c
2021 Rads flow temp. In cold weather 42c
2022 Flow in mild 37c
2091looks for run sinal on B22
@alfapat
2021-2022 make no sense, the difference is so small that its barely bothering with weather compensation at all.
I would set 2022 to 30 or even 27C
The 2091 value confirms to set the external thermostat well above the desired temperature whilst you optimise the WC.
Sorry I still dont know what you are asking here. For now I would concentrate on getting WC right and planning, if you intend to, the bypass of the buffer tank and secondary pump. You are getting there, these things take time because houses respond slowly.
Really! That much of a drop . Should I be trying out that WC anyway, I was just trying to see if there would be a difference between flow from HP and flow out of buffer to CH with the change in WC . Ultimately warm of the house. I do intend to make changes in the set up , but as an interim lower and monitor. I have talked about lowering in this thread before, but haven’t realised that my efforts in small changes were so fruitless. I am just conscious that the costs are so much more at the present setup, than before with my previous one , albeit still too much, patience I suppose? So should I be trying to lower WC at this stage, Oh I will try it ! What can I lose. Desperate times , I’m doing my head in at this thing , where’s my plumber, I’ve never had one , away to find!
Absolutely. 37@15 makes no sense whatever. The whole point of WC is to adjust the flow temperature so that the output of the radiators (which depends on the difference between flow temperature and house room temperature) just matches the demand (loss from the house).
At an OAT of 15 there is almost no demand (assuming you want your room temperature to be about 20). Obviously the house does still lose heat at this temperature (because its warmer than the outside) but there is usually enough waste heat from electrical items and heat from the occupants to come close to balancing that loss. So a very good starting point for the high end of WC (IAT=15) is only just to heat. 30 or even 27 does that. More importantly, unless you get this right, the flow temp will also still be too high in the 7C-12C region, which is where the OAT is most of the time and where most of the money is spent. Please change 2022 to 27 or 30 if it wont let you set it to 27.
(For what its worth the reason some people set a ‘floor’ of 37 is because its the lowest temperature at which radiators still feel warm and doing this avoids ‘my radiators aren’
t warm’ call outs. This is silly and costly, the radiators emit heat even if they don’t feel particularly warm and its the house that you are trying to heat not the radiators!).
Please change 2022 to 27 or 30 if it wont let you set it to 27.
There wont be much of a change in the temperature difference across the buffer as a result of changing the WC parameters. However its ALWAYS right to adjust the WC down to the minimum value consistent with heating the house. You need to set 2022 to 27 or 30 then gradually reduce 2021 until the house is just at the right temperature, with all thermostats and TRVs set to max. Better still reduce it until the house is just below the right temperature, then turn it up a degree. Thats (more or less) the optimum for your current setup. If, later, you remove the buffer, you will need to readjust.
For me to comment on this I would need to know the details of what you have changed, the OATs on the two days before and when you determined the costs, and the actual measurements of costs. However I can say that the fact that FSV 2022 is so high (which has only just come to light) will tend to negate any savings due to WC when temperatures are in the 0-8 region, which they have been recently. This could easily account for an increase because, effectively, you have opened up all the TRVs and thermostats without implementing WC.
The only way to do this is to see it through to the point where the WC is optimised, then test over several weeks. And you have to be ‘all in’ or not in at all. Piecemeal changes that don’t complete the job are quite likely to make things worse. In the end its your system so please feel free to go back to operating it as you had it previously.
I’m quite happy to follow this through as it seems right to with all that is being advised, as its never been right since installation.
2022 is now at 27 and 2021 is 42\
Thank you for explaining that, I think I was getting mixed up with all the numbers.
Its easy to get mixed up!
So now leave 2022 where it is and gradually adjust 2021 until the house is at the right temperature. Allow a week, change once – max twice per day The aim again is as low as possible while still heating the house. Note that may mean you have to push it up a degree given the change you have made to 2022, but only time will tell!
BTW you are doing quite well to be able to run at 42 with radiators and a buffer tank, suggests that your radiators are plenty large enough!
@jamespa
I read a post on here about converting a four port Buffer to by-passing and making a volumizer . What is the advantage of including a volumizer as opposed to by passing and linking ch return through the buffer via the same level and returning the flow to the HP pump as to entering at the top of the tank and back to HP at the bottom.
I remember your drawing and just realised reading similar that I should know more .
I have contacted a local plumber who is yet to visit , to discuss my alterations .
The volumiser provides extra system volume which may reduce cycling or may be necessary for defrost if your system doesn’t otherwise have sufficient water in it to meet the specifications for your heat pump.
It may be totally unnecessary, but it does no harm. So it’s the safe option if you have a buffer.
The second one avoids the possibility that all the hot water collects at the top and is bypassed by the returning flow.
Not a lot really, but perhaps worth doing. I can’t quantify it.
Ok Guys James,
I cannot get anyone to respond to a request locally to come and have a look at converting a buffer tank to a Volumizer therefore eliminating the constant mixing in this .
Is it the time of year or lack of committment at this time of year . Due to colder temps and time of year?
The reason being costs normally should have gone down daily given the OAT at this time of the year. So trying to get a plumber to submit his time and have a look at my system seems impossible .
Shoud I revert to my older system in involving opening lockshields and shuttin down TRV’s to suit rooms . Certainly cheaper than exposing the flaw with the present set up or try and get a company to look at the proposed set up meantime .
Before answering that, what do you feel is the problem which you would solve by reverting. Earlier on you seemed to have made some progress albeit that we both recognise its still not optimal. Why not leave it at the point of maximum progress, what do you think will improve if you change it back?
The old problem we had certainly was not right , but while it was using TRV’s and open lockshieldsand the buffer, the costs were more controlled but still expensive as they were shutting down the system and then the HP had to make it up. I know from my Bills that they are higher than before but only because I am in this in between stage that now the temperatures in the house are more consistant the the whole idea of bypassing the the tank and or making it a volumiser has to be completed in order that the system is optimised , but I cant get someone to do it . I am committed to completing it , and then savings will be even more , Im sure of it , I am down the a flow temp of 40c now , previously 42 for two weeks, meanwhile the daytime temperatures are helping things a little now.
@alfapat PM me and I can help, you will just neeed to find a standard plumber, not a specilaised one.
I have messaged you .
Thank you in anticipation of your help .
At long last , I found a decent plumber and boiler expert locally to take the buffer out of the system(his advice) and change the piping the short distance that I had from the buffer from 22 to 28mm . Also down to one pump on the flow side directly into the CH and returning to HP . DHW remains as it was . A week into the modified system running and seems to be fine , there has been some frosty nights and cold airstream throughout the last two weeks, and that’s reflected with the heating on in the evening . I have brought the water law back to 38c from 40 , OK so far . Is Homely beneficial at this time of year?
c
Really delighted to hear that. I can’t comment on homely but if you don’t have it then you will likely want to readjust your weather compensation curve having removed the buffer. At this time of year it’s probably nigh on impossible to get it right, most likely you will need to wait until the new heating season to get to final values. If you need any help please just ask!
@jamespa So settings to date are as follows for now.
– **2011:** -10°C- **2012:** 15°C- **2021:** 40°C- **2022:** 25°C
I have put 2022 to 38c
Will see how it goes thanks £2900 later !
Good luck, I hope it all works out!