@marzipan71

Hi Steve,

Thanks for the photo's.

A motorised 3-way valve is like the one that is located in the pipework above connection 8 on the TS. The box on the top, with the cable connected, contains the motor assembly, with the valve assembly below. The valve is described as a 3-way, since it has one input port and two output ports, the flow can therefore go from the input to either of the two outputs. The motor moves the valve to output port A or output port B. Most 3-way valves are what is called 'spring return', in that the motor, when energised, will direct the flow from the input port to say output port A, and when the motor is de-energised a spring returns the flow from the input port to output port B.

I suspect that your system may be piped up as shown in schematic 6.3, but replace the gas or oil boiler with ASHP, and remove the solar thermal panels and associated pump and valves. The way in which it should operate is as described below.

The warm water from the heat pump passes to port AB of valve 3UV1. If the system is calling for CH, the water will be directed to port B and flow through pipe c to radiators H1 and UFH H2 via the mixing valve and pump. The return water then flows to valve 3UV3, and would normally flow via the lower port back to the heat pump. If the water in the lower section of the TS (Sensor TR) is warmer than the return water from the heat emitters (Sensor TRH), then valve 3UV3 will direct the flow to the its right-hand port, which is piped to connection 7 on the TS. The water will therefore flow through the heating support heat exchanger and emerge via connection 8, absorbing some heat energy in the process. Since the water being returned to the heat pump has now already been supplied with some heat energy, then the heat pump will not need to work so hard.

If the system is calling for the TS to be heated, then valve 3UV1 will operate to direct the flow from port AB to port A. The warm water will therefore enter the TS at connection 4, pass through the internal heat exchanger and return to the heat pump via connection 3.

As far as I can see, the problem with your system is that the solar thermal part has been omitted. The lower section of the TS is therefore likely to remain quite cool, which in turn could reduce the amount of heating support, if any, that the TS can provide.

From the point of view of minimising running costs, it might be more beneficial to install the missing solar thermal system, which should provide much of your hot water demand and hence reduce the need to operate your heat pump merely for DHW. It would also make more solar PV generation available for export payments.

Conversely, installing a battery storage system would allow more of your solar PV generation to be stored, and used later in place of importing energy from the grid.

Only you can make that decision based upon your lifestyle and energy needs.

With your present system I would suggest that you run your heat pump in weather compensation mode, and set the temperature to which the TS is heated to the lowest setting that you find adequate. Only heat the TS during the mid to late afternoon period when the heat pump should be most efficient. Also try raising the indoor temperature setting by 1C or 2C during the daytime when your have maximum solar PV generation, this should help reduce your heat pump operation during the evening period.

Hi @derek-m thanks for this explanation - makes sense and provides ample background for discussions with Daikin at my end. It does sound like the solar thermal panels are the way to go to free up solar PV for other activities. Batteries are definitely something we are thinking about as well. Your input here has been invaluable.

One thing I'm still a bit confused about re: running in weather compensation mode. My thinking had been that I should leave the heat pump/ general system 'on' at all times running in weather compensation mode and with setback enabled (at 18C) for the night hours, and adjusting the weather dependent setpoints (the curve) for the daytime hours until we find something that's comfortable. The bit I'm missing is that I probably need to use the scheduled timer programs via the Daikin controller to tell the system when to heat, and to what temperature, and when to use setback temps. I presume its through this programming that I'd be able to raise the indoor temperature by 1 or 2 degrees C during the daytime, per your suggestion. Now, if I have the 2 non-Daikin in-room smart thermostats set to (say) 27C to act as temperature limiters (per advice elsewhere on the forum), I'd be setting the desired room temperature in the Daikin controller through the programmed scheduled timer actions, yes? The Daikin controller is located in our 'tech room' and consistently records the room temperature much higher than our actual rooms (due to my dreadful job of insulating the pipe work and co-location of the washing machine and tumble dryer). So if I set the desired room temp to, say, 22 during the daytime and the Daikin controller thinks the ambient room temperature is 24 as we are running the tumble dryer, for instance, won't it think 'job done' and shut of the CH? It was in my head that I wouldn't be directly setting/ programming room temps but fine tuning the weather compensation feature/ curve until we arrive at something comfortable. I think I'm tying myself in knots here... 🤔  

@marzipan71

Hi Steve,

I remember you saying that you have an indoor Daikin unit as well as the outdoor unit, so it would appear that you have what is called a split system. The outdoor unit heats the refrigerant gas, which then flows to the indoor unit where it is used to heat the water in your CH system. There will probably be a water pump inside the indoor unit, which I believe is called a Hydrobox. A photo of the nameplate would probably give confirmation.

When operating in WC mode, the Daikin controller will probably be receiving on - off commands from either of the two indoor thermostats, but the required LWT will be set by comparing the ambient air temperature against the WC curve. The ambient air temperature is measured by a temperature sensor normally located within the outdoor unit, though some systems can have a separate sensor located elsewhere.

The heat loss of a property is a function of the DeltaT between the indoor air temperature and the outdoor air temperature, so if the indoor air temperature remains constant and the outdoor air temperature reduces, then the heat loss will increase. The heat loss will also increase if the outdoor air temperature remains the same, but the indoor air temperature increases.

The primary function of WC is to vary the LWT with variation of ambient temperature, but in such a way as to keep the indoor temperature fairly constant at a desired level. It may therefore be necessary to fine tune the WC curve over a lengthy period of time, under different weather conditions. It should be possible to initially set the parameters for the WC curve based on the normal range of ambient temperatures to be expected, and the estimated heat loss of the property. In the UK I would normally say set the LWT at 25C for an ambient temperature of 20C, and a LWT of 50C at an ambient temperature of -5C. In Italy, you will probably find that with those settings, the indoor air temperature would get warmer as the ambient air temperature falls. In your situation setting the lower end of the WC curve at say 50C at an ambient of -15C may be more appropriate, or a LWT of 40C at an ambient of -5C. The objective is to vary the slope of the WC curve until it closely matches the heat loss characteristics of your property.

I would suggest that you turn both the indoor thermostats down until they are below the indoor temperature, and hence switch off the heat pump. Then note if any of the water pumps are running and the position of all the motorised valves. Increase one of the thermostats and note which pumps start to operate and which valves change position. Turn that thermostat back down and repeat the process with the second thermostat, again noting the results. This should give you an idea of what the various items of equipment are actually doing. Set the thermostats back to their original settings after completing the tests.

I'm not certain how to best set the Daikin Controller for raising the indoor temperature. What you actually need to do is offset the WC curve. Which controller do you have installed?

Hi @derek-m thanks again for reply. Yes we have an ‘outdoor unit’ (‘the big fan’) and an ‘indoor unit’ (‘the big grey box’), and the Altherma ST thermal store. Photos of the outdoor and indoor units below, and I’ve also attached the operation manual and installation manual for the indoor unit. The Daikin ‘remote controller’ (p3 of the operation manual) is installed immediately above the indoor unit, in the tech room with the washer and dryer. Per p10 of the operation manual, you can read the entering water temp, the indoor (room) temp, the outdoor temp, and the hot water supply tank temp from here. However, the field setting 8-00 is set to ‘0’ so the indoor (room) temp actually displays LWT I believe (e.g., 52C at the moment). The installation manual says that only if this setting is set to ‘1’ is the Daikin remote controller being used as a room thermostat. Setting 6-01 (external room thermostat option) is also set to ‘0’ (off) (per p23 of the installation manual).

We have two Bticino ‘smart’ room thermostats (we have the slightly the older model of these here), one for the bedroom zone (UFH) and one for the daytime zone (radiators). We can program these to call for heat (i.e., set blocks of time with desired temps) but my understanding is we should use these as temperature limiters – i.e., set them to both to temps higher than we would require (e.g., 25C). Then set the Daikin remote controller to WC mode as you say.

We haven’t yet turned on the heating for this winter but expect to do so very soon. I have set the WC curve to 50C at -5C, and 25C at 20C. Actually in our part of Italy, winter temps are not too dissimilar from the UK – we probably get more sunny days but average day and night time temps are not that different from the UK. As you say, I’d like to start with these settings then vary if we find we need to per the settings you suggest.

My confusion is how to best set up the Daikin controller with the Bticino thermostats. I have the WC set to ‘on’ with the settings above, and I presume that I then use the schedule timer on the Daikin controller to program periods when we require heat during the day/ evening, and use the setback function at night (room set back temperature of 18 with a leaving water set back temperature of 5C) – and I presume this is what the diagram on p11 of the operation manual ‘schedule timer based on temperature set points’ represents?

If the Bticino room thermostats are used as ‘temperature limiters’ (e.g., set to 25C), how does the Daikin equipment know what the room temps are in the rooms where we require heating? Or is that not even the right question? Sorry for my confusion. I’ve read the various manuals dozen of times and I am still confused by how best to set up the various field settings in order to have heating during the day (perhaps with the heating in the solar hours set a little higher), evening, and night-time. Daikin don’t make it easy, or maybe its just me!

@marzipan71 

Hi Steve,

I need to go out this afternoon, so I will try to answer your questions later.

@marzipan71

Hi Steve,

You are correct that the two thermostats should be set to say 25C, so that the heat pump is always enabled.

It is not you. I have read through hundreds of manufacturer's manuals for industrial equipment, and other than some very poor translations from Japanese, I would rate the Daikin manuals as 'not for the faint hearted'.

I am not 100% certain that this will work, so I suggest that you give it a try and report back what happens.

Whilst it is possible to schedule a setback value, it does not appear to be possible to set a setforward value. What I therefore suggest is that you adjust the WC curve to produce an indoor air temperature of say 2C above your desired indoor temperature. Then schedule a 2C setback to start say 1 hour before you normally rise, this setback to run until the warmer part of the day starts, when it should then be removed. As the warmer part of the day is coming to an end, start a new setback of 2C to run until say 1 hour before you go to bed. Then schedule a 4C setback for the overnight period.

This should provide results as shown below.

Time.    Setback    Indoor Temp

00:00       4C             19

07:00       2C             21

08:00 Get up.

13:00  No Setback     23

18:00      2C              21

22:00      4C              19

23:00 Go to bed.        19

Obviously change timings and setback to your requirement.

Unless you have a Daikin room temperature sensor wired to your controller, then it does not know, and cannot accurately control the room temperature. By optimising the WC curve it should be possible to achieve reasonably consistent room temperature, though they may vary slightly from day to day and season to season.

To lower the temperature in individual room you could fit TRV's, but try not to install too many as they could reduce the flow rate through the indoor unit, and cause the heat pump to short cycle.

Hi @derek-m,

Many thanks for this, most interesting and helpful. So – we have lift-off and I switched the system on last Friday evening (25/11) with modified settings. The Daikin remote controller appears to be a bit simple compared to the flexibility of other and perhaps more recent models from both Daikin and other manufacturers. For instance, I’m limited to a single setback operation in the field settings – its turned either on or off; the start and end time of that operation is fixed; and its only possible to set a single set back temperature – so, in essence, one set back period with a single set back temp is allowed per day.

We do not have a Daikin room temperature sensor, just a 3^rd party ‘smart’ thermostat per zone – one in the Upper Zone (UFH – bedrooms/ office) and one in the Lower Zone (rads/ seating areas and kitchen). I set these to permanently ‘on’, at 25C. My understanding is this means they are acting as temperature limiters and will only interact with the ASHP if the room temp exceeds 25C when it/ they would send an ‘off’ signal to the ASHP.

We have 7 radiators in the Lower Zone, and they all have TRV’s fitted which I’ve opened fully, except for one rad in the cloakroom which is set to ‘3’ as otherwise it just gets too hot in there.

I set up the WC curve as follows:

Setback operation was scheduled for 2200 until 0700, at 18C.

Its not possible to set an actual target room temperature in the Daikin remote controller if weather dependent set point operation is selected (unless I’m missing something – and begs the question how would the unit sense the 18C value in setback operation?). When programming timed heating periods, it seems to me the only way to increase or decrease temperatures is via a ‘shift value’ which would move the WC up or down for that particular timed period in a range of +5C or -5C.

To start with, I programmed the scheduled timer of the Daikin with a single, constant timed heating period (i.e., 24hrs) – again, its not possible to set a target room temp and the only control is via the weather dependent set point values. The setback function always takes priority when turned on, so that gave us basically a binary ‘on’ state operating in WC mode; with setback 'off' between 2200 and 0700. Delta T for the LWT/ RWT was set to 5C.

The Daikin remote controller doesn’t given any downloadable data; nor does it tell you COP etc. Here’s the manually-read data from the room stats for the first day of operation:

It was getting uncomfortably warm, so I decided to change the WC curve to the following:

We’ve since been monitoring the zone temps with these settings and it looks like this:

We might tweak these down a little as its possibly still a little too warm. Overnight outdoor temps 27 to 28/11 (last night) were down to zero - first frost of the season - but the house stayed a constant 21C.

One thing puzzling me is that although we have the setback on overnight, the room temps do not change – the overnight temps are as I say stable at 21C. The setback is definitely stopping any heating during operation, but the room temps don’t drop. Since the 2 room stats are set to 25C, we cannot control the individual zones, and once they are to temp (i.e., 21C) they seem to hold their heat, which means the bedrooms are also at 21C when we go to bed. We don’t want to drop the lower zone (TV room etc) to 18C in the evening; conversely the bedrooms at 21C are too warm…so is there a solution if we essentially have a single zone? The only way I can see that working is to set the Upper Zone room stat to 18C in the early evening to allow the rooms to cool, but that breaks the rule around using the room stat as a ‘temperature limiter’?

I very much would like to implement the temp bands you provided, and I think the best way to do this is to use that programmable shift value function on the current WC values – so maybe an additional program between 1300 and 1800 with a shift value of +2C, which should increase the room temps to 23 (maximising solar) during that period. I think I'll try that modification next and see how we go (and report back).

All in all I think the system is performing much better using the WC than it has done in the past. The room temps are more stable, and both zones are more or less the same temp which is much better than past performance. I'm really pleasantly surprised that the radiators are warming the rooms so much at such a low flow temp. I’ve also validated that we definitely can run the UFH and rads at the same time, which I wasn’t sure about in the past. Electricity consumption seems to be trending much lower for the heating compared with previous winters as well.

@marzipan71

Hi Steve,

Thank you for the very detailed report.

Yes, I think that you are correct that using temperature setback will not work in WC mode, you need to use the WC offset if possible.

To lower the bedroom temperatures I would suggest using TRV's, though you may be able to use the thermostat if there is a zone valve, which I assume that there is. Control the upstairs zone using the thermostat, but leave the downstairs thermostat set to 25C.

As you have probably realised, indoor temperatures change very slowly when in WC mode, since the heat energy supply is very close to the heat energy demand, when the system is correctly adjusted. It is therefore important to make an adjustment, and then wait until the temperatures have stabilised before making any further adjustments. The settings I gave were a starting point, and will no doubt need adjustment for your own personal requirements. What you may find is that because the indoor temperatures remain fairly constant, it could be possible to lower the temperature slightly and still feel comfortable, thus saving a little more energy and money.

Hi @derek-m - thanks once again for feedback. Its clear to me now that I'll need to use the offset to adjust the WC curve and thereby produce a different room temperature to the WC curve programmed via the field settings - your earlier comment about Daikin manuals comes to mind. Not anywhere near as clear as it should be...and also made me think of the Daikin installer telling us not to 'push buttons' as they wouldn't be responsible for any subsequent perceived poor performance. Anyhow...

Our set up is a little bit different in that we have UFH in the bedroom areas and rads in the sitting areas, so to lower the bedroom temperatures while maintaining the sitting area temp will require me to use the thermostat to shut off heat, while maintaining the sitting area thermostat at 25C - thanks for confirming this approach. We are going to let the current WC curve settings run for a good period of time before assessing whether we need to adjust; I also want to see what influence the new settings have on consumption since I have 3 winters data now to compare approaches. Finding data of this kind on the internet is a bit of a challenge so useful I think for me to post it here just in case other users have similar experiences - Mars' data was tremendously useful to me in understanding how our heat pump should behave under different climatic conditions.

@marzipan71 our installer kindly left the below on the heat pump controller. Needless to say we changed all the settings immediately and got far better efficiency than they had it set up to deliver. I assume it wasn't left as some kind of ironic joke

Posted by: @batalto

↑

@marzipan71 our installer kindly left the below on the heat pump controller. Needless to say we changed all the settings immediately and got far better efficiency than they had it set up to deliver. I assume it wasn't left as some kind of ironic joke

-- Attachment is not available --

Too funny @batalto...in our case, our geometra/ project manager and electrician conspired to order us an ASHP that drew 6kW of power in use...when the supply line to our house is 6kW here in Italy, which they knew. After we moved back in to the house, of course the power would trip out when the ASHP attempted to run. Eventually, Daikin were called back to apply 'carefully considered settings' which enable the ASHP to work, occasionally, but if we tried to run anything else at all bar a few lightbulbs the power would trip out. Not Daikin's fault, but it left us with 'carefully considered settings' which were then inappropriate for when we had our supply upgraded to 20kW. Hence the ongoing battle to try and optimise our settings.

Just for the record here @derek-m and @hughf I re-discovered the brochure below which I think describes the system I have (more or less) - a snapshot in time from 3 years ago and perhaps not what would be installed now to solve the same problems - but may be of interest to anyone reading this thread in the future and trying understand my particular issues:

This shows outdoor units from the same series - ERRQ - as mine (ERRQ016AAV1) connected to an indoor unit from the same series - EKHBRD as mine (EKHBRD016ADV17). The recommended DHW tanks/ thermal stores (i.e., the 'stacked' grey boxes similar in design to the indoor unit) do not correspond to mine, but that is possible because, as I stated earlier, we were looking for a large volume TS to accommodate a small guess house/ extension we were planning to add to our property. The brochure TS's are 200 or 260L, whereas ours is 500L. That said, on Page 5 they show a model from the TS range that we have - the white box with the grey top rather than the stacked silver boxes. The configuration on Page 5 looks exactly like ours - the indoor unit on the ground next to the big white TS.

The bits missing from our system are the solar thermal arrangement, which I'm almost certain could be added; and the Daikin room thermostat EKRTW which I assume could be added to replace one of the Bticino 'smart' thermostats I have installed currently and might give us a bit more flexibility with room temps, holiday mode, etc which we don't currently have. The strange thing is the necessary PCB for the indoor unit (EKRP1AHTA) to enable use of the room thermostat, and the installation manual for the room thermostat, were both left behind by our (non-Daikin) installers. I suspect the room thermostat was therefore provided with the Daikin kit (i.e., we paid for it) but taken away by the installers when they realised we had requested the Bticino 'smart' thermostats when we were totally ignorant of the way the ASHP should function. At least they forgot to take the PCB away with them!