Good afternoon. Looking for information on the heat pump that I installed in my home, located in an internal area of central Italy, I came across your site. My system consists of a Samsung AE120BXYDEG/EU + AE200RNWMEG/EU and the MWR-WW10N remote control. The heat pump heats a house of approximately 250 square meters (with aluminum radiator system) on two floors in the countryside. A damp and cold place in winter. The system seems to work quite well but I have some doubts that I think you can help me resolve. The settings for WL are “2011” -5°" and “2012 15°” while the water outlet temperature is “2031 45°” and “2032 35°” the ASHP is controlled by remote control with an internal temperature of 19.5°. The pump takes almost the whole day to reach the set temperature but I noticed that it continuously modulates with an absorption that varies depending on the outside temperature. This can be seen in the attached photo.
I also don’t know if the COP is reliable by detecting the data recorded by the MWR-WW10N regarding the electrical consumption and the energy generated. I think that the energy consumption is calculated including the production of hot water. You can see the peak of 3 KW for about 25 minutes relating to the production of hot water. Using the data from the remote control I have a COP that varies between 3.6 and 3.9.
Are you able to share a few more details of your installation? Do you have a volumiser/buffer tank? Do you have a fixed speed or PWM circulation pump? What is the typical circulation rate/LWT/RWT and do they show the 2-minute variation like your power consumption does?
On the face of it, your Water Law settings are reasonable (though maybe slightly high according to the CoP chasers on this forum) and your house heat loss (from 1.7kW consumed x 3.75CoP = 6.4kW) is believable for your house size if you live half way up the Apennines, at this time of year.
That your house takes a long time to reach roomstat setpoint is not unusual, especially if you reduce it overnight (“setback”) and your house is not well insulated and/or your radiators are too small.
Apart from the apparent compressor speed variation, which might be explained if your system volume and controller hysteresis are small, you seem to have a reasonably well-controlled arrangement.
You may want to consider slightly raising the WL curve by increasing #2031. This will make the heat pump heat the house faster, although COP will be reduced. You could also consider reducing the nighttime setback.
This modulating electrical input is quite normal for a Samsung, take a look at the other Samsung heat pumps on HPM: HeatpumpMonitor.org. It’s nothing to worry about. It looks like your heat pump has been setup well.
Thanks SarahH and glyn.hudson for your answers.
The system has a 25 liter buffer tank and is separated into two parts the heat pump sends hot water to a heat exchanger that has its own circulator that runs at a fixed speed and sends water to the radiators. The technician who made the system insisted on putting this heat exchanger. I didn’t agree much especially because in my opinion this way a loss of efficiency is generated. However the system seems to work, in this period it is only turned on from morning to evening for about 10 hours, so I can make the most of the photovoltaic production. The following morning the temperature is about 18.2 degrees Celsius with a night loss of about 0.7 - 0.8 degrees Celsius. The house has very thick walls of 80 cm on one side and 45 on the other the windows are very well insulated and the attic has a 12 cm rock wool coat. The temperature during this period also dropped to zero degrees and I was able to observe some heat pump cycles which I assume were for defrosting.
I also have this pump (8KW) and already regretted it. Not that it is not heating or something but Samsung did a very bad thing with these pumps and that is - they are lying. Your pump is not 12KW. My pump is not 8K. Our pups are 14KW pumps crippled down in software!
What are your heat loses ? Because it has 14KW compressor this pump is not able to modulate low enough. It can go lowest to 800W but at this point is very inefficient.
As an example 2C outside, 42C water temp 23C indoor COP2.9. But this is not the only issue, this poor graph of modulation aka zigzag pattern I have all the time, especially on warmer days. I have also AC units and these does not modulate like this at all. What is this ? I can see it all the time.
My heat loses are 4KW@0C and 23C inside roughly so this pump running well with my Type 21 radiators bellow 0. But if there is 10C outside it is very ineficient and cycling. At -20 I have 8KW loses and if I would know that I would buy a pump with max.8kw which can modulate down to 300W which would save me lot of hassle. At COP4 I would have nice 1200KW which would be great up to 15C which is ideal. -20 we don’t have it at all and min temps are -15 for few days in a year.
Yes, that time I was stupid knowing nothing about heat pump. Now I would not buy it definitely.
Also Samsung control unit is one disaster especially for seting water law curve. Why for god sake you can go lower than 10C ?? It’s impossible to set for me becaue I need to run flat at 45C until -5 and then gradually increase water temperature until -15. All bad here…
But back to your problem, you have radiators and that buffer tank is small. Giving your system and target flow temperature your dT might decrease too fast because at this flow temp your radiators will not be able to give heat away and then the pump will starts to throttle to give your radiators time to exchange the heat. But because you have very low flow temps, your radiators will not able to do it and the dT continue to drop despite the fact the flow temp is already at very low level. For the pump to not overshoot the target flow them it starts to reduce compressor and fan as well. At this point the HP is not running in optimal range at all and only tries to not overshot your target temp. But for radiators 35/45 is very low. They are not able to transfer heat and that’s why your dT is dropping. Since you have thermostat the pump will keep running in this most inefficient mode until the thermostat turns it of. But this can take very long time at low flow temperature. So you are underheated and in a most inefficient way. Congrats
What you need to do is to increase your flow temp. For radiators set 45/55 at 15/-5 and it will be much better and even your COP will be better. Pump will cycle occasionally but depending your hysteresis it might be only few cycles a day.
Hope it’s understandable, English’s not my first language
Thanks for the reply Michal_S Misiak. Sorry but I only saw now that your reply was there. To be honest I have never made an exact calculation of the heat losses of the house. I started to be interested in these things only after they installed the heat pump. Here where I live the temperatures are not as low as in your country. Last week we had -2 but it is something that happens only a few times during the winter, mainly the temperatures are around 0 degrees in the morning and 13 degrees in the afternoon. The pump is not doing too badly and the COP is around 3.7. I do not see ON OFF and at the moment I keep the pump on only 12 hours a day from 8 AM to 8 PM with an internal temperature set at 20°. I will try to increase the water temperatures as you suggested to see if the zigzag pattern is reduced.
No problem, to be honest the temperatures here are not what they used to be Now we have +2C and barely drops under -5C even in winter. Do you have floor heating or radiators ? 35 for radiators is quite low temperature. But your house is big so you need lot of emitters. Not sure if you have thermostat or running by water law but I had quite issues with pure water law mode so I’ve installed thermostat. I keep indoor temp at 23C and it is able to modulate at lowest fan and compressor speed with efficiency penalty to around 10 - 15C. But usually it is turned off by thermostat sooner or later. SCOP would be a better parameter to COP becuse COP tends to change pretty much. E.g. I can have COP 3.5 and 7C and at 0C it’s below 3.0 and even lower when it is freezing. It’s a penalty for radiators and higher flow temperatures. But my seasonal cop is around 3.5 so I’m quite fine with that. For the zigzag pattern just ignore it, my pump is doing the same…
You may see some funny spikes every 5 - 10 minutes intervals starting 1:25. Don’t know what is it could be heater for dripping tray or pump running because at night the pump is turned off.
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