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Topic starter
10/10/2021 9:42 am
Hi
I exchanged a few emails with Mars and he referred me to this site, and encouraged me to paste my questions and first experience with my newly installed air to water heat pump.
I sincerely apologize for this being so long, because I want you all to get a good picture so that you can give me the right answers, and I basically copy-paste my conversation with Mars with a few changes to text
Also sorry for my grammar and style of writing, 'cause English is not my native language.
I live in Bosnia in the countryside in a double decker house around 230m² (160m² is living area, 70m² is not being used). My previous heating system was a furnace runned on wood and coal. A month ago I installed a heat pump system, with all new piping and larger radiators (Vaillant) specialized for heat pumps. Since the beginning of October I started using it, because we had a really great September till the end with temps up to 26 'C. It's been working a couple of days now with outside temperatures between 2 to 10 'C. Today we have 4 with chilly winds, and the first snowfall in the mountains, Bosnia is mostly mountains, like Switzerland but without the banks 🙂
I had a lot of questions and didn't understand what was the best setup for the heat pump, how to use it efficiently etc. and I didn't quite get the answers from the serviceman, so I googled around (a loooooot) and your videos with your really complex setup helped me the most.
Here are some specifics:
- 16kW M-thermal Split air-to-water heat pump by MIDEA
- it's only used for heating (vaillant radiators)
- It's NOT being used for sanitary/domestic hot water (very important)
- but I do have a 200l buffer tank, to accumulate hot water (I understand the benefits of that)
- house is very good insulated
Now I'll explain the setup and how it is working and performing these days and how I think it should work, based on watching your (Mars) videos and reading the manual (because there are many types of setup).
So because it's a split system, the indoor unit is located in a room of the house or as Mars called it "nerve center" in his vids, in this room besides the indoor unit is the buffer tank, the main piping goes from there to the radiators, the wired controller which is connected to the indoor unit,my main switches and the external circulating water pump (the usual red one - I'll refer to this one as external, because the heat pump like all has its own internal circulating pump, which the serviceman told me is only powerful enough to push the water to the buffer).
HOW IT WORKS NOW
So, on the indoor unit the only step I do is to put the unit ON, and set the target water temperature, which is these days on 43'C (I plan to set it to 45, or maybe higher because we have colder winters then the UK), all my rooms get warm enough. The compressor starts, water gets heated up, the internal water pump pushes the water to the buffer tank, I can see the temperature rising on the buffer temp readers. Now before I continue, I have to say that I have a SALUS wireless room thermostat like the one Mars been talking about, but the thing is the serviceman connected the counter part of the Salus room thermostat (the signal receiver) directly and only to the red external circulating water pump. This is what confuses me the most, I asked them why, why not connect it to the heat pump as I read in the manual that it can be done this way and on the indoor unit I can see the connections and writing "for room thermostat" - and they gave me the answer that it is "better" this way and more efficient, i was like OK you are the professionals. Moving on, after turning on the heat pump and setting water temperature (on the wired heat pump interface), I also at the same time set my salus wireless room thermostat to my desired room temp, like 22'C the receiver gets the signal and turns on the red external circulating water pump. From a cold start (water temp. around 18'C), the radiators get to the desired water temperature in about 1-2 hours, if I for example turn the heat pump off overnight and start it in the morning, the buffer tank still has mildly warm water in it around 30'C) so the radiators get warm pretty soon in about 15-20 minutes, so that is a huge advantage of the buffer temp, the heat pump doesn't' have to do much effort like from a cold start.
Now we are getting to the interesting part. After reaching the desired room temp on my Salus, it emits to its counterpart to shut off the red external water pump, and it does. Now some would think, depending on how cold it is and on the insulation, the temperature on the Salus would drop eventually and the two would communicate again to get the red external pump on again, but this doesn't' happen...my room temperature even rises sometimes up to 1-2 degrees, and yes it gets to worms in our house...also the radiators doesn't get cold or "cooled off", some would say great but for me it's not, first it's to warm, second to lower the room temp I have to either open a window, shut down or lower the target water temp on the heat pump manually.
Now this is why, as the room temperature is achieved and the red external circulating pump gets turned off by Salus, because neither is connected to the indoor heat pump...it's logic that the heat pump keeps on doing what it's doing, heating the water to the buffer, and eventually what is happening is that it seems that the working internal circulating water pump of the indoor unit is strong enough to mildly push the water towards the radiators, in combination with the principle of expansion of hot water it is possible (hot water it rises up pushing down the colder water). The radiators do not get warm enough as if the red external one is working but they do still emit warmth and don't "cool off". I asked around and a few people confirmed this. So now my concerns, besides obviously it's getting too warm for my taste, is the efficiency - why does the heat pump indoor/outdoor unit have to operate if I don't have any need to. The outdoor unit which is the fan coils and the compressor do shut off at certain points, because the heat pump is set to a differential of 4'C to shut off if the set target water flow temperature is being exceeded by these 4'C. But only the outdoor unit gets shut off (fan coils and compressor), on the indoor unit the internal circulating pump is still working, meaning it still mildly pushes the water and when the flow temperature drops again to the set value, the outdoor unit kicks in again.
At a 43'C water flow target, the outdoor unit operates for about an hour to two then stops due to the above and starts again after maybe 20 minutes. Is it OK to work like that? Because when the red external is OFF, I do have a cozy room temp which is sometimes even higher the the value I set it od Salus RT...and basically I am worried about the internal circulating water pump because it's always working and pushing water even to the radiators without the help of the external red one, that it could eventually fail, maybe it can handle it, IDK.
So as it operates now, I think this is a misuse of energy and hot water from the buffer tank, because the desired room temperature is still held. So the thing I do now is to shut the complete heat pump off once during the day and overnight, and when I notice my Salus reading drops below my desired room temp and the external red kicks in, than i manually again turn on the heat pump, and because the buffer tank has worms water accumulated, the heat pump doesn't have to do much effort.
HOW I THINK IT SHOULD WORK
So basically the last lines above is how I think it should work, Mars and his wife/partner are talking precisely about that in their video episode 7 "How We Control Our Air Source Heat Pump '' from minute 08:35 to 08:50 and continues from 10:35 to minute 11:00. To quote her: "The Salus RT is basically what calls for heat....giving instructions to turn the system on..."
In the manual of my heat pump this configuration is explained and possible to configure and activate this option on the heat pump interface, I do not understand the wiring but if I go with that I will call for professionals...basically the receiver of the Salus RT will be also connected to the heat pump, and acts as a switch to turn the heat pump on or off - in the manual it states that by doing so if the heat pump gets the signal from the Salus RT to shut of, than both the red external circulating water pump and the internal water pump in the indoor unit will be turned OFF (and of course also the outdoor unit). Meaning, no more water from the buffer tank will be pushed towards the radiators (they than do get "cooled off", the buffer tank accumulates warm water longer and when there is a need for heat from the Salus RT both of them come back on again, but the advantage like already said above is the accumulated warm water in the buffer tank, so the radiators get sooner up to temperature and the heat pump got it easier. And overnight or when we are at work, away or else I can just lower the temperature on the Salus RT, without fiddling around with the water target flow or turning the heat pump manually off.
So regarding efficiency would you agree with this method? Your system (Mars) is a lot more complicated with floor heating and much more stuff going on, but I think in my case, with no need for sanitary/domestic hot water etc, just heating - then this is the way to go or should I leave at as it is?
I realise that this mail is very long and once again apologize, I hope you get the picture. Feel free to ask me if you need further info.
Best regards to You all, Mirnes
4
Topic starter
10/10/2021 10:04 am
worms
sorry for autocorrect at certain points 🙂
15283
kWhs
10/10/2021 12:25 pm
Hi Mirnes,
Welcome to the forum.
Thank you for the detailed description of your system, which highlights one of the main problems that people encounter with heat pump based systems, 'how should it be set up for best operation'.
As you have correctly stated, your system has two water pumps, one (pump 1) inside your heat pump system which pushes the water into the buffer tank, and one (pump 2) after the buffer tank which pushes the water around the radiators. Because the buffer tank is just an insulated vessel, with flow and return pipework connected to the heat pump at one side, and flow and return pipework connected to the radiators via pump 2 on the other side. So, what would appear to be happening in your situation, is that even when the room is up to temperature and pump 2 is switched off, if your heat pump is still operating, and pump 1 is running, there is sufficient water flow from pump 1 to push the warm water through the buffer tank and around your radiators. During milder weather conditions, this water flow can be sufficient to cause the indoor temperatures to continue to increase above the desired setpoint.
The easiest solution to your problem would be to have your system rewired, so that the thermostat not only switches pump 2 on and off, but at the same time starts and stops your heat pump.
For improved efficiency, it would probably be better to configure your system for weather compensation. I can give you more details about how to set up your system if you can provide a full list of all the equipment and controls. The manufacturers name and type/model number of each piece of equipment would be adequate.
4
Topic starter
10/10/2021 4:10 pm
The easiest solution to your problem would be to have your system rewired, so that the thermostat not only switches pump 2 on and off, but at the same time starts and stops your heat pump.
Thank You for your quick reply, I was really hoping to get this kind of answer. I myself also find this the most logical, and just needed this kind of assurance, 'case next week the company who installed the heat pump will address my complaints, and they are as well interested to my claims regarding radiators still getting warm water even external pump is OFF 🙂 so it's good to have the opinion and confirmation of others to better argument my case.
After I rewire my system to this way, I will test for a few weeks, and also wait for the October electricity bill and post back the results
tnx again
2
Topic starter
14/11/2021 5:31 pm
Hi,
here are a few updates, as I mentioned above my heat pump was working till the end of October without correct wiring with my RT and the external circulating water pump, so basically I had to turn it ON or OFF at the interface of the unit itself, with the exception that I did manage by myself to wire the circulating water pump directly to the heat pump unit (ignoring and turning OFF the RT receiver, for now) - so when the heat pump was ON, so was the external water pump and vice versa when the unit was OFF.
This gave me at least the advantage to use the schedule option on the heat pump the second half of October. Me and my family are home all the time due to covid and home office work, so the heat pump was working every day and I scheduled it to work for up to 1.5 to 2 hours and then to shut down for 1 hour depending if it's night or day, over days it was ON like for one hour and OFF up to 1.5 to 2 hours.
Temperatures in October ranged from 0 to 10 'C. I kept the waterflow temperature at 40'C, and didn't feel the need to set it higher because I achieved around 24 'C room temperature 30-60 min after the heat pump was ON.
So my electric bill came a few days ago, I compared my October bills from previous years and they all were more or less the same...I was positively surprised that my last October bill was only 70-80BAM (around 35 GBP) higher than previous October bills, and to be honest I expected at least double the amount and would be more than satisfied with even that, so you can imagine how surprised I was 🙂
For months like December, January, February if the bills would be triple the amount I still would be more than satisfied. Just to point out, in previous years I spent between 600 to 650 GBP for a heating season using wood and coal.
Moving on, from the beginning of November finally a certified technician has wired my RT to the heat pump, I enabled the room thermostat option and now as @Derek M said, the RT switches everything ON or OFF depending on the set temperature on the RT.
Outside temperatures stil range between 0 to 10'C, waterflow temperature on the heat pump is still 40'C. On the RT, I keep the temp at 23 to 24'C - over nights a little lower, and what I noticed is that the heat pump has shorter ON/OFF intervals than I used to manually turn it ON/OFF or with the schedule way. With RT the unit works in cycles from 20 to 50 minutes and when the room temperature is achieved it turns OFF and stays OFF until room temperature drops and the RT turns it ON again, more or less it stays OFF for 20-30 minutes, over the day or with higher outside temperatures it stays OFF even longer because room temperature is held. Due to shorter ON/OFF intervals, the water temperature in the buffer tank and the pipe system doesn't cool OFF that fast, and the outside unit doesn't have to do much effort to achieve the waterflow temp again.
I've done a kWh reading on the induction meter today, to calculate how much energy I spent for the first half of November, and basically I am under half of the kWh consumption of the whole October, so for November I would think that I will achieve the same kWh consumption or maybe even lower.
So that's it, what do you think of the ON/OFF intervals - are they OK, are they anything I should track/check or adjust, because now I have the comfort to raise the temperature more than i need on the RT just to let the heat pump work for a longer period of time, or to lower temp on RT to keep it OFF for a longer time....but if these ON/OFF intervals are OK, and doesn't effect the heat pump or it's efficiency I would just let it all handle by itself.
Best regards
2
15283
kWhs
14/11/2021 7:46 pm
Hi Mirnes,
I appreciate that English is not your first language, and my Bosnian is non-existent, so if there is anything that you don't fully understand please let me know and I will try to explain in a better way.
Thank you for your detailed description of how your system is operating.
Since your original post in October, there has been a great deal of discussion on the forum about the most efficient way to control a heat pump system. It has been decided that in most cases, the most efficient way to control a heat pump is to use weather compensation.
Let me first of all explain how weather compensation works and then how it can be set on your system.
Inside the outdoor ASHP unit is a temperature sensor, which measures the outside air temperature. This sensor feeds a signal to the indoor controller to tell it how cold or how warm it is outside. As you are no doubt aware, the colder the outside air temperature, the more heat energy that is required to maintain the desired indoor temperature. So if the outside air temperature is say 10C, to keep the indoor temperature at 21C may require a water flow temperature of say 32C. If the outside air temperature falls to 0C, then it may now require a water flow temperature of 42C to keep the indoor temperature at 21C. What is the minimum outside air temperature that you normally get in Winter? This will give you some idea of the settings for the lower end of the weather compensation curve.
By correctly setting the parameters for the weather compensation within the indoor controller, it is possible for your system to automatically vary the water flow temperature, to the correct value required to maintain the indoor temperature at approximately the correct level. By keeping the water flow temperature at the minimum required to meet the heat demand, you should find that your heat pump operates in the most efficient manner and keeps your energy consumption to a minimum.
I am not that familiar with the Midea ASHP controller, so if you would like to contact Batalto (who I believe has a Midea ASHP) on the forum, he will hopefully be able to guide you through the process of setting up your weather compensation.
If you need any further help then please get in touch.
4
15/11/2021 9:22 am
@batalto, can you help in any way?
Buy Bodge Buster – Homeowner Air Source Heat Pump Installation Guide: https://amzn.to/3NVndlU
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15/11/2021 11:05 am
Call and ye shall be heard.
If its anything like mine - big IF - then you first unlock the controller and go to
- MENU
- FOR SERVICEMAN - CODE 234
- HEAT MODE SETTING
- 3.8 Is your max flow temperature
- 3.9 if you min flow temperature
- 3.10 is the lowest temperature at which you will have maximum flow e.g. -5 degrees
- 3.11 is the maximum temperature at which you'll get the lowest flow temperature
If you have the M-Therm model (like I do) this is the manual -
Password is: midea2020
Page 87 has the explanation on all the settings.
Also on YouTube you can view videos by Freedom Heat Pumps - https://www.youtube.com/c/SamsungEHSHeatpumps
They have a number on the Midea unit (that I have anyway) and they explain lots of things about its set up, fault codes etc.
2
Topic starter
16/11/2021 2:15 pm
Thank you all for your kind responses...I always have the goal to keep my writing short, but I doubt it...but maybe this essay will help someone in the future 🙂 But I will end this with basic YES or NO questions.
First @batalto thank you for joining the thread and the input you gave. On my unit I only have options from 3.1 to 3.7, they are all set and I know what they mean. The other options are not there or are configured somewhere else.
My unit is a M-Thermal Split (Indoor: SMK-160/CD30GN1-B Outdoor: MHA-V16W/D2N1) The wired controller looks like in the picture attached.
I have the manual and found where to enable preset temperatures for weather compensation, like the "weather temp set" option and the settings to enable and set the "climate related curves" (in heat mode there are 8 curves for LOW temp and 8 curves for HIGH temp). Currently the option to use the weather temp set for heat mode is OFF, and I adjust the water flow temperature (mainly it's on 40C) manually on the unit, and quite frankly will keep it that way for now, because I am always home and it's kind of confusing, so I will elaborate to see If I am reading it right 🙂
I can set the water flow manually up to 55C , T1S Range in FOR SERVICEMAN>HEAT MODE SETTINGS is set to LOW, so 55C is max (stated in the manual, while on HIGH = 60C is max). The tech guys set it to LOW because I don't use the heat pump for sanitary water and they said that most heat pumps anyway achieve up to 55C, and that there is no need for 60C or HIGH setting.
The manual points out when it's like this on LOW, and if I enable the weather temp set option for heat mode, I can select the curves from 1 to 8 for LOW temperature, it states in the graphic table that for the LOW temperature curve, 38C waterflow temp is the maximum for curve 1 at -20C outdoor temperature, for zero degrees outdoor temp, water flow would be 35. So this means when the unit works like this, and it's zero degrees outside, automatically the unit will get waterflow temperature only up to 35C if I select curve 1 (curves 2 to 8 of course have lower waterflow).
I doubt that 35C waterflow at 0C outdoor temperature will keep me warm when selecting the highest curve 1 🙂 So I am guessing I would have to change in FOR SERVICEMAN>HEAT MODE SETTINGS and set to HIGH, by doing this when I enable "weather temp set" I get the option to choose the climate related curves from 1 to 8 for HIGH temperature, and the graph in the manual shows that maximum water flow temperature than would be 55C for curve 1. I would go with curve 5 (picture attached of graph)
So questions:
1. Enabling weather temp set/weather compensation basically adjusts the water flow temperature for me, instead of me adjusting it manually from time to time
? (I know it's a YES, just to confirm)
2. If I would go with weather compensation and enable "weather temp set" and select my preferred curve, am I assuming the above right? That I first have to change in FOR SERVICEMAN>HEAT MODE SETTINGS and set to HIGH, and after doing this I can select a curve listed for HIGH temperature?
3. This question relates to my previous posts regarding ON/OFF intervals of the unit. Now that my room thermostat turns everything ON/OFF depending on given room temperature, should I be concerned if sometimes the unit turns OFF just after 10-15-20 minutes of work because it achieved room temperature and the RT sends a signal to turn it OFF, or vice versa it turns ON after 10-15-20 minutes of being OFF because room temperature drops. Sometimes I notice the unit starts and works for like 10-15 minutes and STOPS because my wife is making dinner and the room temperature rises half a degree duo to the oven, or we have guests who smoke and we open a window...the room temp drops and the RT starts the unit again after being OFF just for a couple of minutes. It's more a need to understand if these shorter ON/OFF cycles are bad for the unit, a friend told me not to concern myself with this...to just set my desired room temperature on the RT and let it be 🙂
4. A mix question involving Qs 2 and 3 🙂 If I enable weather temp set/compensation, this option has nothing to do with my room thermostat? Meaning, enabling weather compensation will only automatically dictate water flow temperature on the unit based on outside temperatures , and my room thermostat will act like it does now...like Derek M said, be the switch for turning ON/OFF the heat pump based on what room temperature i set on RT?
Attached:
- heat pump wired controller
- from manual regarding heat mode settings (LOW or HIGH)
- from manual regarding LOW/HIGH curves
16/11/2021 5:29 pm
I can't comment with any authority on the Midea ASHP or controller. However, it sounds like the answer to 4. is yes. That's how my ASHP was set up by the installers. It worked OK. However, it does result in the thermostat turning the ASHP off and on. Some opinion says that it will be more expensive to run this way. From what I have read, as long as the turning on and off is not consistently more than 3-4 time an hour, itwon't harm the unit. Is there a sensitivity setting on your room thermostat will stop it reacting to small variations in room temperature?
15283
kWhs
16/11/2021 6:46 pm
Hi Mirnes,
Were you able to download and access the manual sent by Batalto, and is the manual similar to your manual?
From what I can see in Batalto's manual, you can either select one of the weather compensation curves from the high temperature list shown, or it may be possible to create your own weather compensation curve which is a closer match to your requirements.
Obviously, the ambient air temperature rises above 20C in the Summer, but what is the coldest temperature in the Winter where you live?
Topic starter
16/11/2021 8:06 pm
@Kev M
ON/OFF cycles aren't more than 2-3 times per hour, so glad to hear that that even 3-4 times isn't harmful to the ASHP.
Posted by: @kev-m
Is there a sensitivity setting on your room thermostat will stop it reacting to small variations in room temperature?
As for this, my RT is a non programmable Salus RT-310RF, it only has the two DIP switches on the back, one for CHP (cycles per hour, 6CHP or 9CHP, it's on 6) and the other one is the TIP switch which is in deed in charge for the sensitivity/change of degrees in the room temperature (Span +/- 0.25C or +/- 0.5C), but it's already set +/- 0.5C temperature change. Setting it to Span +/- 0.25C would only result in more frequent on/off cycles.
Were you able to download and access the manual sent by Batalto, and is the manual similar to your manual?
Yes, I was able to DL it, went through it a bit...some things are the same like with most ASHP, but the manuals aren't that similar. In my manual, I also can only select just one of the 8 weather comp. curves, but first I think I have to select HIGH (because now T1S Range is set to LOW) in serviceman > heat mode settings to be able to choose one of eight curves for HIGH tempareture "weather temp set / climate related curves" option . It's my question 2, maybe Batalto could clarify about that?
Posted by: @derek-m
but what is the coldest temperature in the Winter where you live?
Last few winters were normally to mild, in degrees I would say we had during December, January and February only a couple of days with temperatures around -7 to -10C, I checked accuweather recordings, and the average temps for these months seemed to be -5 to +5 and warmer.
The last really cold winter, that was way out of the average, and it was also one of the coldest ever recorded here, with almost 30 days straight below 0C, with a couple of days with temps from -15 to -25C we had I think 2017, hopefully that one won't come again soon 🙂
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