so you can choose: either run with COP that is lower, but the power input is low, so accept it, its running in steady state at a low power input , thats a good state to be in , and the energy cost overall is nothing to be worried about. Or, run at the higher temp, then the room temp sensor will cycle as the house warms to it set point . you can always experiment with a slightly higher WT to see at what point it cycles on the room stat, you don’t have to go all the way to 40.
If you’ve got yours down to stable state of 2kw output I’d be very pleased, others with the 8kw unit haven’t got close to that.
I don’t have too much heat. I have a large house that has not brilliant insulation. 3.7 to 4kw in 10C weather is only slightly too much, the house will cycle on the room temp stat sometimes, but its does not happen excessively.
FYI I’ve found my system doesn’t behave nicely with the water lower than about 35.
This is how it is with my Mitsubishi. Overall, I’ve had better performance and comfort since switching to using room temp sensor. I don’t find the 1°K hysteresis be particularly noticeable.
It does appear that a number of units are happier at 35C than at 25C or 30C.
It would be enlightening to be provided with extended performance maps from the vendors here. It isn’t (or shouldn’t be) a large part of the overall space heat load delivered at these kind of temperatures but could still be material.
What is it average performance ?? What type it is ? Mono R32 ? How many KW? I’m little bit afraid of homely because I fear there is not much settings I can change. Maybe I will drop them a message and kindly ask if they can provide me some registry address when flow temps or outdoor temps are set.
You said it tries long and low this is what I already have until it is so low than it cannot go lower. Wonder if Homely is able to change parameters on the run. E.g. if it sees that power is to low and it is cycling too much, can it increase LWT a bit ? I don’t know.
I have to say I’m pretty impressed with mine. Today it was pretty hot (average temp until now 8.7C) and this this is running all the time with minimum water temperature 33C. Indoor 23C running constantly! Saw it running at 600W min. completely silent operation. Returned home and thought it’s not running. Had to walk 1m from it to hear it. Pretty impressed.
Granted, COP is “only” 3.2 on 8.7C average but the comfort is great.
Don’t know what happened before 9 to be honest. Looks like it was so hot it couldn’t go lower as sun was shining? That stop cycle is pretty short. Guess I need to increase a water temperature a bit. But otherwise it is running whole day.
But again this 3 minute off cycle! My brain can’t process it Why it is so short ??? Anyone knows ? So it was running again for 20 minutes and then thermostat shut down the pump and it was off until 16:00. But it was really hot.
There is high probability you are right. I would say they’ve took everything from gen6 and probably tweak some paramters because this water law mode works really strtange for me. And you right, the fan can run deliberatelly slow and seems it goes to it’s limits just to hold target water temperature. Really saw it running at 600W with water temp 33C. Wish I can use flat until 0C…
I would not say they were artificially low but we had a Russian gas Then Germans closed their nuclear plants so should we be surprised ? The best is that Europe is trying to save the world why US, China and other big countries completely ignore this climate crisis.
Don’t scare with 30 - 50 cents. Then I would need to hunt fro a COP as Mat. Buy new radiators and install solar panels all over the roof lol
You are very right. It’s really interesting how you can play with COP. Today it was very hot like 12C and saw it it cycled once but the water temperature was really low - 33C.
This 8KW I guess completely shut off the fan but it was not able to maintain such low output. I don’t know exactly what was the power output but it must be lower than 2KW. I need to increase water temperature a bit. I’m really sad I can not set it up in two steps. From 0C and above like 38C flat. And then from 0C and bellow with water compensation curve. Seems without modbus and some programming I won’t be able to to that. And it’s only because engineers in Samsung set a limit of 10C for warm weather and I cannot get lower. If they would not limit it or allows 0C then it would solve all my issues. Can’t get why they did this
Yeah, so my pump would be ideal for you
Seems it’s not very stable on mine as well at lower than 35.
I also had to switch to room sensor. In water law it was not stable at all for some reason. Seems it this mode is programmed to run as best efficiency so it has never lower the fan speed. Need to observer more here but I’m pretty fine with room sensor. 1C hysteresis I can register because in fact I have a feeling it’s more.
I have to 2nd this. Samsung provides only max. heating capacity which is quite useless. I think they are doing this intentionally because numbers in low range would not be that impressive
Never mind, I will but DWH tank to increase my efficiency little bit more. Now I have electric boiler. Then loser COP at higher temps won’t hurt me that much
What if you detected the compressor stopping and then remove power from the heatpump until [0,20,40] minutes past the hour so the compressor can only start 3 times an hour?
Thank you. Seems I can achieve better SCOP without Homely so not sure if it would give me some benefit. I guess I will program something with modbus.
Btw, do you know what setup this user is using for all those measurements ? It’s pretty impressive.
Compressor on this unit can start every few minutes. Saw it starting at least 6x per hour. It is always 3 minutes off for some reason. I guess it’s because I have probably low water volume or there is some issue with pump. I’ve noticed that pump stops when compressor turn off so could be that water in unit losses heat to fast. I thought it should circulate the water. I don’t know but I have to observe this behaviors. However, this was only in water law mode.
Not sure what do you mean exactly but the compressor was running all the time at minimum input - you can see it from the graph. Only the fan was barely spinning.
Have a timer that turn the power on at 0 minute, 20 minute and 40 minute past the hour and that turns the power off when the compressor stops. The would prevent the compressor starting more then 3 times an hour.
Yes, but would be pretty uncomfortable and really not good way how to control the pump. Conditions are changing constantly and you can’t rely on this schedule.
The idea here is to detect when the compressor turns off at the end of a cycle, and turn off the power so that it doesn’t restart after 3 minutes, allowing for the water in the whole system to cool down a bit. Then, after some reasonable length of time (10 minutes is decent), turn the power back on.
This was explored more fully in this topic I mentioned before:
Solution can be done with hardware, as Ringi and John proposed, or possibly via Modbus. I did something similar via Mitsubishi’s cloud service.
Ah, like this. Now I got it. Yes, this is interesting idea. Yes, there are many ways how to do it, probably will check something but now seems there is no issue with it.
Anyway, my plan is to buy modbus and make a java application which will run on Raspberry Pi and constantly monitoring parameters read from modbus. After evaluation I will program logic to set the weather curve flat when temperature is +5C and above. Either 40 or 45C. This will give me much better COP than keep it running on minimal power with fan barely spinning. And probably I will integrate some weather provider API to change the curve when there is a sunny day.
I can’t agree with this statement. This is truth only if you have well dimensioned pump which can cover your heat needs across all weather conditions and best with floor heating. Especially when freezing this is ideal, yes, but…
…I’ve clearly proved that in warmer climate, with radiators… to let it run constantly is inefficient. My COP at +12C is the same as COP at 0C. The only advantage is the thermal stability but that’s it. And very silent work of the outdoor unit which maybe not good for fun at the other hand. Even running the water at 50C would be more effective than this. I would expect at least COP4 at 12C…
Rather then having a fixed minimal “off cycle” length, I think setting the “of cycle” to be longer if the “on cycle” is shorter would be more stable. I question if there is ever a need for more then 3 “on cycle” per hour.
If the water pump can be kept running then it would be improved by increasing the water volume in the system with a inline volumizer, so the radiators remain warm while the compresser is forced to be off.
(Shame there is not a standard design to bypass a volumizer until dt reduces to about 6c, so the volumizer does not slow down the heating of the building until the heatpump has catched up with demand.)
Yes, this is a good idea we have discussed here with marko. Volumizer should really help to prolong cycles. The only question is why this pump behaves differently in “water law” mode and differently in “indoor” thermostat mode.
In indoor this pump can lower its performance as lowest as 2KW by decreasing the power input of compressor to minimum and limiting the fan of outdoor unit to bare minimum. Not very efficient but helps maintain pump on as long as possible.
What I don’t understand that if the pump is not able to do this anymore, then it will switch off but is stopped only for 3 minutes and then starts again. Really the water temp decrease that much it has to kick in again? Volumizer would be good idea here maybe.
Yeah, I’ve seen Glyn did this so at least I can get some registers from it, but I’m not very keen in python. I’m mostly java developer so it would be easier for me. I saw some java libraries for R485 USB converter so this should be possible. I also need to records values from pump somewhere into database so I can evaluate them and do some actions on the pump.
I said this several times. In Water Outlet mode, the ONLY thing its using as a control input by default is the temperature of the outlet-side water in the outdoor unit. it is NOT the water in the radiators, or a volumiser or buffer.
As soon as it goes to an off part of the cycle, this water cools down. because its outside, it cools quickly. So then it detects the drop and restarts, after not long. It is an entirely useless mode unless you have some other control input as well. Such as a 3rd party thermostat, or a modbus controller.
If you have the coding skills then you could run in water outlet mode, and use modbus to adjust the water outlet setpoint dynamically based on whatever rules you desire to code. Drop the outlet water temp right down. Or just simply turn CH off via modbus - there is an on/off register for that.
This is basically what homely does, but they are doing it as a service.
I strongly suggest you don’t do a relay to actually power down the unit, thats a really bad idea IMO. turn it off in software.
You are right with this but what this water law is good for then ?? I can’t get it I’ve posted this in another forum for one guy strugling as well but this is insane behavior in WL mode?!
Look at these two screens. One is with water law, the other is indoor thermostat.
It always heat to 35C, then stop, pump off after a minute, within another 3 minutes temperature drops to 33C and it starts again ?! What is this shit and then it’s running for 5 minutes and the same shit again.
This is in indoor mode. Continual work… Ignore those cyan spikes, it’s my electric boiler So WL completely ignored here and it’s off only by thermostat.
Now tell me this is normal… This WL seems to me completely screwed up. You can see it start with high power input around 2KW then it goes down slowly but this heats up water very quickly in warm water so the pump is running for 3 minutes. I simply don’t understand.
I’ve tried all the 3 WATER PUMPS modes and all behaves the same. Water pump is always switched off one minute after compressor then it’s off for 3 minutes and always compressor starts. There is no waiting of another 7 minutes like in manual. Can’t get this…
Definitely. It’s really a bad idea, especially if this is done in freezing temperatures.
Marko, this HP should work like that but it’s simply not… I don’t know why but there is a mode @2093-3 where the PWM pump should circulate the water. But it does not follow this settings. After a minute the pump shut off and the water get cold of course, so I guess this is the reason for cycling. I don’t know.
I think that when installed on a well designed system and correctly sized for the property, this heat pump will work well with water law mode. If the radiators are undersized or the heat pump is oversized, then water law just doesn’t work.
We see the same across other manufacturers too. Pure weather compensation only works when the whole heating system has been designed properly. Room thermostat mode is what many owners have to resort to in order to get reasonable performance.
Some better models have “weather compensation with room influence”, which is somewhere in the middle, and may work for some systems.
Looking at the 110 systems listed on HeatpumpMonitor.org, only 46 are using Pure weather compensation, no room influence. Half of those are Vaillant Arotherms. Average COP is 3.8.
Of the rest:
20 Weather compensation with simple set point control (dumb thermostat) (COP 3.6)
17 Weather compensation with a little room influence (mostly Vaillant) (COP 3.7)
Yeah, seems we can agree on this now. Definitely my system is not optimal with those radiators I have. But it’s a nice finding that this pump can go as low as 2KW by varying fan speed…
Here one other guys uses an external thermostat and the compressor can be turned off only by this. It has hysteresis of only 0.4 which would be great for me. As a bonus if external thermostat is used you can use water law temperature offset directly on Samsung controller (instead of ability to change only temperature in roomstat mode).
Every day something to learn.
I regret a bit I did not find this site sooner and those comparisons on heatpump monitor. Maybe I would choose something else. But I’m not disappointed (yet) with this Samsung
Yes this inner thermostat… 1C hysteresis not great and you can’t change water temp offset. So I guess will try external one instead. Some wifi model or what.
I can see my HTQ has pretty much worse performance in comparison with older gen6 model But could be because the leaders are smaller units. Now I’ve realized the title of this board is wrong. It should be gen 7.
Why it is so short ??? Anyone knows ? So it was running again for 20 minutes and then thermostat shut down the pump and it was off until 16:00. But it was really hot.
