I was experimenting with my new radiators to see if i could get a COP of 5 from the heat pump as it should be able to do.
I then wanted to see how well it could do for a day so I had windows open.
I haven’t hidden any of this, I state it clearly in post 57
One point to note is that my temperature is from upstairs where it is cooler, the OEM device that measures this doesn’t work so well downstairs as it works by wifi.
But here is today, no windows open and it will still run for six hours until it is forced to cycle.
Ah sorry I’ve missed that part with opened doors and windows. Then yea, for test this is good indeed. So you were able to get COP5 at 12C to 14C. This is nice.
Also now you running on nice COP. I can get around 4 with my rads… So yes, I could use bigger ones, let’s say T2 but I would need to calculate output but I guess it’s only 30% more or so so I guess it’s not worth that 1 COP point or ? If there is colder outside this difference is even lower.
Seems you still don’t understand how it works. I will try to explain it. It’s funny since I’ve realized this as we went through this discussion
If pump uses thermostat it still tries to follow the heating curve you have set. So you have started at 6 and everything was cold and around 6:30 the pump reached the point on the curve. But you can see it will continue to operate infinitely until it won’t get the command from thermostat to switch it off or you manually turn it off like you did 6h later.
BUT, this does not mean your pump is able to maintain the target flow temperature. In fact it is not and you can see it from the graph. Since 6:30 it is constantly increasing the flow temperature (not sure what is that drop at 7:00) while maintaining the minimal power input (in low power mode the pump is less effective). This way the compressor never turns off!! It will constantly raising the flow temperature slowly until it reach the max. allowed temperature for heating water. This would meat at this point you would have a spa in your house. Look at 12:00 - the air temperature is higher than it was at 6:00 but hey, your flow temperature is higher than it was in the morning while it should be less… Hope you see now that your pump is NOT able to maintain the flow temperature at given outside temperature. Therefore you have to turn it off by thermostat or manually.
This is difference between indoor mode and weather law. In indoor it heats constantly and only limiting factor is max. allowed water temperature. In weather law it simply stops once the temperature is above the target flow temperature. And this is what I was referring to but not that this is not normal, it is for sure, but the problem is that pump stops only for 3 minutes before it resuming operation and this causes heavy cycling. This is the main problem of weather mode of this Samsung unit.
So conclusion is, in mode you use you will hardly see any cycling but this is same for me if I use this mode. For example now it is running for 3 hours and my target flow temperature when I’ve started was around 33C ad 10C outside. But now it is still working but with higher flow temperature (35C). But since this is producing more heat my thermostat sooner or later turn off the pump. So as you can see I also can run for 6h only with less efficiency…
No. Old model was totally different compressors. Rotary compressors more like the AC units.
This high temperature model uses a scroll compressor.
Probably yes but this may need some work to avoid spikes.
On that vaillant unit when the setpoint changes it runs at 100% output to reach the setpoint then modulates down; but when it chooses to cycle because setpoint was reached it doesn’t run at 100% output because it isn’t too far from where it needs to be.
You will need to “tune” how cold you allow the radiator to get before you call for heat again. Otherwise it could be choosing to run at full power instead of the efficient part per setting.
That “tuning” will dictate the cycle time. More system volume may or may not be needed so that it does not cycle too often.
It should be mandatory.
A 12 kW unit turning down to 4 and managing 14 kW in a mild climate is very decent.
8 kW turning down to 4 is also ok. Problem appears to be control logic at these part loads
And it’s not the quietest on the moment either!
Some other features are also neat, such as the antifreeze heater on the plate heat exchanger.
Just for information and from observation. It is really interesting how the pump works in “indoor thermostat” mode during warm weather.
Now it’s 12C outside and the unit is running at 33C of water temperature constantly ! (it’s funny that in weather law mode it cycling like crazy, there must be something wrong in the controlling logic). I’ve simply though it can’t work because it delivers so much heat but seems this is not the truth and obviously it can deliver 2KW constantly!
But way how it is running is interesting. It runs at minimal compressor input of 700W and it can’t go lower. This is the bare minimum for compressor to work. BUT, the fan is barely spinning! It is almost stopped. This means it maintains this very low water temperature but with pretty low efficiency. I’m getting COP like 3.15 only at 12C. I have this COP normally at 0C!
Wow… So radiators are almost cold and the heat losses are spot on. BUT, the price is pretty high for this since at 12C an 35C water I should have normally (when compressor is running at nominal speed) COP of 5.7! So it’s pretty inefficient and would be better to run at 40C water for better efficiency!
Problem is that tis will break my weather curve pretty badly. I’ve set minimum water temperature for heating at 37C but seems this is completely ignored in “indoor temperature” mode. This is code #1032.
I need 40C for 0C outside temperature but would nee to hold this temperature also at +15C. So flat from 15C to 0C and then 55C at -15C. This is not possible at all so someone tell me this controlling logic is not poor with Samsung unit ?
So I guess my only option it this case is modbus with raspberri pi and write my own script which will constantly monitor the parameters and change my water curve on demand. Up to +5C it will use the curve I’ve set and from 5+ it changed it to flat and heat at 40C outlet. Do you know there are registers for that ? I can also change hysteresis this way. But I can see this will take me some time to understand all and program it but do I have any other choice ? I would like to do it in java, does someone know if there are libraries to work with R485 to USB converter for linux. JSSC ?
Seems it can down much more to 2KW but with lower efficiency. COP3 vs COP5.5. 4KW is probably at fan spining fast
Thanks. I think you misunderstood me because doing so I would have for 0C 40C water, for -15C 55C water but for +15C I would be somewhere around 25C. You can set only 2 point with this Samsug. For some reason I’ve set #1032 to 37C but it’s completely ignored by the pump. It’s still running according water law.
What I need is:
From +15 to 0C … 40C water temperature
At -15C i need 55C water temp.
With your settings it would be like this:
And I need this:
The reason for that that mine radiators are able to deliver 40C water at 0C with pretty good COP of 3+. But if there is 15C outside mine COP remains almost the same because pump is working currently at 33C at minimum compressor and FAN speeds which is very inefficient. I need to be able to deliver more heat in shorter time to get better efficiency.
What is ridiculous and prove that Samsung is stupid to be honest that it shows me eko level 4/5 which indicates it’s running very effectively. But the reality is it checks only if outlet temperature is above or bellow 35C. If it’s above I have 3/5. If bellow I have 4/5. It completely ignores compressor and fan speeds. Funny. Would expect more from Samsung engineers.
UPDATE but when I’m thinking and looking again that curve is also not OK because it’s very steep so with modbus i need to program in a way that until 0C outside it works flat at 40C and if it’s colder it will use -10C/50C and 15/30C. This way I can get what I want… Plus maybe I will program some real weather compensation on sunny days… Seems lot of fun I have.
You are causing us a lot of data overload, Michal .
But for your information, the water law curve is not extrapolated as you showed in your first graph. Look again at the diagram on p22 of the User Manual. Above the #2012 value, the LWT line is horizontal. So in your case if you set #2012 to 0degC and #2022 to 40degC you will get 40degC at any ambient temperature above 0degC.
@SarahH Oh well, seems I’m not that stupid, I cannot set #2012 to 0C since minimum is 10C I knew there is some culprit. Why they even limiting this for god sake ?
Yeah, at least I’ve realized it’s not extrapolated as I’ve thought. This is pity it’s limited like this because it would resolve all my issues. I really don’t understand these stupid limitations of parameters. What is it good for?? I thought these parameters are for “expert” and no ordinary users who will never figure out how to access them so Samsung should assume we know what we are doing.
So since this won’t help mi as 10C is far high outdoor temperature seems really the only option is modbus with some programming allowing to monitor parameters real-time and change heating curves on demand.
FSV 4051,4052,4053 as per this manual. these give the target DT to be (attempted to be) maintained when the HP is in “stable heating” state (so not doing DHW, not still warming up, not just cycled). the way it maintains is by varying pump speed with PWM. So only of any use to tweak these in a system with a PWM pump that is running stably. I’ve done this on my own system so I know what it does. It is not relevant to the problem under discussion, it doesn’t give you a better “low load / short cycling” behaviour.
Thanks. I found that it’s able to run stable but not in water law mode. What is strange that it runs stable in indoor temperature mode. So the last day was really warm weather something between 12 - 15C and I was surprised that it worked continuously! It was running at 33C water temperature. Saw compressor was running at 600 - 700W and the FAN outside was barely moving. COP only 3 but hey, it was running constantly delivering about 2KW of heat!
I thought the min output is more towards 4KW. This water law mode needs to be somehow broken because of this cycling all the time while in indoor temperature control it holds just fine though less effective. Still not fully understand.
Yeah, probably I should have bought a different brand haha. Now I need to fix it myself damn
I wonder if I can override these hard limits in registers ? I know controller won’t let you set min temperature lower than 10C but with a modbus this can be overridden probably. Would be easiest but not sure if it won’t thrown an error.
What is Gen 7 exactly ? It’s HTQuiet ? R32 or that newer version with R290 ?
I have HTQuiet R32 8KW, not sure if it is gen7.
This one but for 3 phases (AE080BXYDGG-EU):
Do you run in water law or indoor ? In water law I’m not able to maintain to run constantly and it turns off/on very often above 5C. But in indoor it obviously can… If you limit the fan speed that you will dramatically lower the efficiency so pump is able to deliver lower output.
I’ve derived it from my heat losses at 10C. Also from power monitor. If it would deliver 4KW at 10C I would have a spa soon in my house. But temperature hold nicely and my calculated heat loss is around 2KW at 10C. Almost all my radiators were almost cold so it’s easy to say it really outputs only 2KW.
I believe it could go lower than this if the fan stops completely. I didn’t try it yet. But I tell you I was completely surprised when I wen out and didn’t hear the pump while it was still consuming power. I went closer and saw FAN spinning veeeery slowly. Maybe 10% or 15% of the full speed.
Funny that in weather law it’s not able to work like this… I think it tries to maintains some optimal performance so it thinks a constant cycling is a good way to achieve it. Or maybe I set something wrong I don’t know, need to play more with this.
Sorry but what do you mean exactly ? What external temperature ? Could you elaborate ? You may set 2 points on a chart and connect with line. Then you get the curve.
Yes Michal, the Gen 7 is the R32 Mono Quiet series, so it sounds like you and I have the identical ASHP (mine is AE080BXYDEG/EU).
I run mine with #2091 = 3 (i.e. enable 3rd party roomstat and control LWT from either roomstat or Water Law (whichever is lower).
I don’t have cycling problems like you, but that’s because I have a much higher Water Law curve (I run mid-40s LWT at typical winter temps, say 5-7degC), and I seem to lose a lot of heat from external piping (to be confirmed) so the ASHP is happy to run at ~50% speed (~4kW heat generated) most of the time.
Also I break all the rules and only run the ASHP during the day (i.e. a big setback at night) so any surplus generated energy is used to gently warm the (large) living room from ~19degC to the 21.5degC roomstat setpoint during the morning. (Effectively, I’m using the thermal inertia of the room to absorb glycol temperature fluctuations.) I get a lousy CoP (2.8) for a few (4-5) hours a day, but the daily winter average CoP is well above 4, so I’m happy.
@marko Michal is correct. As far as I can see, the minimum ambient temp that can be applied to the LWT setting is 10degC. Maybe that’s quite cold for South Korea so that’s what they programmed the controller for…
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I knew there is some culprit. Why they even limiting this for god sake ?
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