Samsung Gen 6 8kW Efficiency

matt-drummer · 23 January 2024 19:37

Hi Michal,

I just turn mine off when I have enough heat, it is never caused by my radiators because they are big enough to cope. When they were small I had poor COP and/or short cycling.

The only way to make it run for longer is to create conditions for your radiators to deliver 4kW at the ambient temperature, bigger radiators, lower flow rate or higher flow temperature.

I don’t know what room temperature control you have but if you have or can add something you should be able to set it to come on and go off within a range of temperatures.

It’s a problem with a heat pump that has a very narrow window of operation.

My heat pump is not too big because the rated output is too much, it is because, in most of our conditions it just doesn’t go low enough and that is because it is not a 9kW heat pump, it is a 16kW heat pump that has been de-rated at the top end, I have 25% to 55% of the output of the 16kW model, it’s rubbish.

And this is exactly what you have, a bigger heat pump that has been limited at the upper end, you may as well have had the biggest model available as you would be no worse off than you are now except for the extra money they would have extracted from you!

billt · 23 January 2024 19:40

How have you come to this conclusion?

My system has a speed controlled pump and it seems to work properly as far as I can see.

Starts off at high flow (1.44cu.m/hr) and 8kW output until it’s got up to temperature then gradually drops the flow rate, ultimately down to 0.44 cu.m/hr and 3kW output to maintain a DT of about 5C.

Michal_S · 23 January 2024 20:07

Hi Matt,

Well yes, but I simply don’t want it to deliver 4KW when there is +5C outside. I want in that case to switch the damn unit of for at least 30 minutes before it kick in again. Do I want that much ?

You know this way it could be even more effective because the water in pipes gets cold and once the pump starts it can take lot of heat from outside easier. I don’t understand why we can’t configure it like this. But I think with external thermostat this is achievable since it simply turn the pump off and allow to turn it on only when indoor temperature decrease under certain level. Then it will take the pump much more time to heat it to the level until radiators won’t be able to expel the heat out.

What do you mean you turn of the heat when you have enough? Manually or how ?

I don’t have any control, only Samsung controller unit which is basically a programming unit with some kind of thermostat. I’ve switched to indoor temperature now but seems it still cycle so I don’t know the purpose yet I need to observe. No any other external thermostat whatsoever. Until now I have it in “water law” configuration which controls LWT. Still don’t understand how it works

That statement it’s 9KW it’s 16KW is very correct. I have the same problem, it’s not 8KW but 14KW. Idiots. They should state it clearly! They’ve crimpled it in software it can’t go more than maybe 60% of 14KW unit but of course the low end is same for all. Pure idiots indeed. Shame on Samsung for this. Really. Most funny fact is that 12KW and 14WK units are completely same by design. They are crimpled in software that 12KW is limited 20% lower than 14KW but 14KW costs 1000 eur more lol. Really idiots. And those bigger models are even little bit more efficient. But it would mean also more heat lol so probably it would cycle even more. Jesus, how stupid I was. So what now ?

@billt what pump do you have ? HT Quiet 8KW ? Could you tell me which hardware/software you use for this nice monitoring ? If you have HT version, how much can compressor go at lowest power ? I saw 1.0KW at lowest

matt-drummer · 23 January 2024 20:19

Your Samsung 12kW and 14kW produce no more heat than your 8kW at minimum, that is the problem.

I just control my heat pump manually, I turn it on when it is too cold and off when it is too hot.

It is usually too hot so I often just open windows to get rid of heat, I could turn it off but then I have to go through the initial often inefficient and unpredictable heating phase so choose not to bother, it depends how warm it is outside.

I have a room thermostat with the heat pump, it is a Daikin unit but not very happy with the house and heat pump, I get too much heat and it over powers it.

There is no escaping the minimum heat produced, it is what it is, you have to deal with it or change heat pump.

All the radiator, pump and pipe work upgrades in the world will not change the fact that the heat pump puts out 4kW as a minimum.

You need a room temperature controller, do Samsung make one to go with the heat pump?

Do other makes of room temperature control work?

Without something to stop it, you will have to control the heat pump manually , otherwise it will continue to try and put 4kW of heat in the house, it is what you have asked it to do by turning it on.

A disappointing few days I am sure!

What now?

A room temperature control of some sort, open windows, control manually or get a different heat pump.

Or maybe you can get less heat by playing with flow rates and temperatures.

Of course, your COP won’t be great if you are stuck with 1kW of electricity but maybe you can lower the heat output once your pwm cable arrives?

Robert.Wall · 23 January 2024 22:39

I’ve promoted you - should be OK now.

Michal_S · 23 January 2024 23:50

Many thanks Robert. I appreciate that. There is really lot of information needed here

Michal_S · 23 January 2024 23:55

Thanks to @Robert.Wall who promoted me I can post now so I’d better keep this separate so it won’t get lost

Ah I see, but seems your climate is different. Here you can have -5 at night and during a day +5 or more so doing this manually would be a lot of work. For example now it’s 0C and there is a forecast for tomorrow midday 11C Jesus, won’t sleep because of this what the pump will be doing I guess it will cycle every 5 minutes… I can’t believe someone in Samsung could set the logic like this. At the moment it is running quietly and constantly at minimal power at 1 degree Celsius.

Yes, who knows how is the efficiency but in my opinion if I turn it off for 30 minutes and then on this will save more as if I would overheat the space or open window to get rid of heat. I don’t know.

Yeah, that’s the issue. Seems it’s a bit big for my house but here I’ve looked to some other pumps and to be honest they are even worse. E.g. look at this inverter mono:

This is 8KW unit but look at the cold temperatures; at -15C and 50C water it outputs 4.67KW lol which would not cover my heat loss. Even -10C would not cover them. So here you can see my decision why I’ve choose Samsung HT. This will heat my house even at -20 like nothing.

And look at minimum power - this is poor as well. At 5C it runs min 1KW outputing 4KW of heat. This would be still too much for me and it would cycle anyway. Same as this samsung but maybe less depending how it is configured. And I can’t buy lower output units since I need at least 7KW at -15C. Maybe I would need to upgrade a pump but these temps are not usually and can live few days with colder inside.

So I would be pretty OK with Samsung in case start/stop cycle interval can be prolonged. For now, no one gave me an answer for this. I guess the only option is to use external thermostat. My problem actually is not that radiators or piping can deliver sufficient heat, problem is they delivers too much heat at given outside temperature. I could switch it for bigger ones or better pump for a flow but it won’t help me with excessive heat

I’m telling you, this is the controller from Samsung. He can choose between “water law” or indoor temperature. I had it set to “water law” so it regulates by same magic based on temperature curve and LWT. And then you have this indoor settings which looks like kind of thermostat but seems it does not work like that. Seems it’s not just a on/off switch when target room temperature is reached. Until know I did not understand how it works. But I saw it switch off the pump at target temp and then started the pump 4 minutes later while indoor temperature did not drop a bit. Really a mystery but I think It’s shit and I need to use really an external thermostat which will send signal to pupm to simply shut off and then turn on.

Does this look like room thermostat or ? Does anyone know how it works ? I would expect it has some hysteresis setting e.g. +/- 0.3 so if I set I want have 22C in the room then while the pump heating it will shut down the pump at 22.3C and then turn on at 21.7C. I don’t know why this stupid Samsung controller does not do this. Really. So if anyone can explain it I would be happy.

Well, a little bit but I didn’t give up yet External temperature control sound like the best idea. I can buy something which is working over Wi-Fi where I can set target temperature and hysteresis and connect it to MMC unit as an external sensor. Then hopefully it bypass the Samsung controller and will work as I need it. I plan to set it only in case outside temperature will be higher than 5C since bellow the pump can work continuously. But let’s see maybe the PWM regulation of flow will help here as well…

I’m not a COP hunter to be honest. Better if the pump can run continuously or if it can’t then I will keep it off for some time. This constant starts of compressor and fan are not good for longevity. So if I will have SCOP 3.5 I will be happy. Even 3.0 I would take

I don’t know to be honest. What I hope is that it will make cycling less often. PWM will make heat pump to lower the flow so I don’t know what effect this will have. But from what I know it can regulate it from 7 l/s to 16 l/s. My max. flow is not the best and it’s either because of some obstacles in pipework or the water pump is not strong enough.

glyn.hudson · 24 January 2024 00:33

I use the Samsung controller as a thermostat like this. It still uses water law (weather comp) to set the flow temperature based on the outside temperature and WL settings, but it will also switch the HP off when the indoor temperature set point is satisfied. It has 1C of hysteresis with is non-adjustable i.e it will wait for the temperature to drop by 1C before switching back on e.g. if the set point is 20C it will switch off when the house reaches 20C and then switch back when the house has dropped to 20C. Obviously for this to work the Samsung controller needs to be located in the living space rather than a plant room!

@Michal_S I wouldn’t focus too much on cycling and trying to optimise for the longest runtime, this may not always equate to the highest efficiency and lowest running costs. Here’s an excellent video by John Cantor on this topic:

Since updating the firmware on my heat pump (I had an old model) to get PWM pump control to work, I’ve found that I’m able to run a bit lower flow temperature and have longer runtimes since, it’s too early to draw conclusions yet, but It’s looking like this might result in slightly higher efficiency, it’s a marginal benefit, but I would try and get PWM working if you can, but it should be possible to get good performance running at constant speed pump, as I demonstrated last year.

Michal_S · 24 January 2024 07:29

Hi Glyn, did you that if you set 20 it reached this temp, it’s off until it drops to 19 and then turn on right ? Still I don’t understand why there is no hysteresis possible to set on this controller. E.g. 0.5C. 1C is pretty big drop you may fell.

Could you please reattach the video ? It was removed.

I will get PWM cable today so let’s see if it run better in higher temperatures. I still don’t understand why this pump has so short cycles… Really. I would be ok with 15 minutes or 20 minutes but 7/3 is very short and it’s only 5C here. What it will do when there is 10C or 15C ?

Your pump would be much much better for me and I regret I didn’t investigate more. I could find this forum sooner but it’s very hard at the beginning if you have no idea and you only find out when you buy it. As I can see from graph it can go as low as 500W power input which would solve my problem and that thing would not cycle until +10C! Unfortunately this shit I’ve bought can’t go lower than 1KW

@Ian_Calderbank @matt-drummer @SarahH

Not sure if there is not some other problem. I just watch how it works

Flow temperature was 40C
Return 32C

So this is dT = 8. It even didn’t reach dT = 5. It didn’t approach dt=5 and it turns off the pump, why ??? Could it be because flow was too low and dT was increasing instead of decreasing ? Flow was 9.2 lpm. I can imagine that if I have PWM the HP would require flow over 20 lpm so not sure but maybe this is also problem? I really hope that by installing PWM regulation to my pump it can work more efficiently. Really hope.

Set indoor temp is not satisfied but for some reason the pump switched off! How ? Why ?

Also what do you think - can those short cycles have an impact on a HP life? How bad is for this scroll compressor to turn off and on every 7 minutes, or 3 minutes respectively.

My problem is now that I set desired temperature to 23C but the pump never got there because of short cycling. It reach max. 22.5C for this reason. What can I do guys. Increase LTW ? But then the curve could be pretty steep. I like 40C at 0C - if it’s running constantly it can satisfy my heat losses and temperature. But when there is 5C outside 40C can’t be delivered by my K2 radiators and current flow.

Well, I’m doomed

Here is the graph from last night. It wen fro1C to 5C in the morning and cycling nightmare started:

MikeJH · 24 January 2024 08:42

Hi Michal_S, I am relieved that Glyn has given you his advice. The answer is to use your wired controller thermostat. I would reduce it to say 18 deg C. It should switch off at 18.5 degC and switch back on at 17.5 degC. At the lower room temperature, your radiators will be delivering more heat at a given LWT, so your heat pump should run for at least 30 minutes at a time

I have a similar, but not so severe problem as you. When my 12kW Samsung cycles, it cycles every 7-8 minutes. My understanding is that the Samsung compares actual LWT with the desired LWT based on the water law settings. When it has reached its minimum output, as soon as less heat is removed by the radiators than its minimum output, the LWT rises and the compressor switches off (even as little as 0.5 degC rise). The water pump continues to run and unless you have a very large system volume (mine was over 100 litres and still short cycling), the LWT will drop by 2 degC within 3-4 minutes and the compressor will start again. Glyn has a video showing you how to schedule different times for different required room temperatures.

Michal_S · 24 January 2024 08:55

Hey Mike, thanks for reply.

So how do you think I should set it up. I want to have indoor temperature set at 22.5C. So the pump will heat up until it reaches 23C and then switch off and wait until it drops to 21.5C ? Or how it works because as you said if the system is not bit enough then RTW drop fast and pump will kick on again even though thermostat is still satisfied with the room temperature. I would need to prevent this so the pump really waits until the temperature drops to 21.5C and only then starts to heat.

You said 7-8 minutes… I have the same. You also have HT Quiet ? 8KW and 12KW are basically the same units only top power input is limited by software (and little bit smaller evaporator/condenser).

I still hope PWM pump regulation will help at least a bit with this shortcycling.

Michal_S · 24 January 2024 10:49

Beauty of this HP cycling. This is really extreme. 9C outdoor temperature. Can anyone tell me what shall I do here ? Indoor temperature set to 23C. Actual temperature 22.8. I think it is LWT/RWT difference which is shutting down the system before indoor thermostat even kicks in and send or or off signal.

Flow still constant 9.6L/m. Target LWT around 36C.

Ian_Calderbank · 24 January 2024 11:26

I think some of the information thats gone round about the behaviour of the controller when its in room temperature mode isn’t correct with regard to the hysteresis. Or if it is proven correct for that persons system then perhaps its the case that different samsung systems genuinely have different hysteresis behaviour? Which could perhaps be due to firmware (of which I have no knowledge, only speculating) ?There’s certainly no setting for hysteresis that I can find.

the way mine behaves, if set to 21.0, is this:
call for heat constantly until temperature reaches 21.9. switch off. house cools to 20.9. switch back on.
so the hysteresis for me, is +0.9 -0.1 . that is if there is no short cycling of course, if its in stable output.

in your observed case yes, it will still be calling for heat if controller is set to 23 and actual is 22.8. So what then takes over is the LWT/RWT difference being too close, if they are too close it will shutdown and cycle on the 7/3 timer.

the best fix for what you are getting is more emitters. A higher target WT is also worth a try as that increases emitter output, not guaranteed though and obviously less efficient.

Michal_S · 24 January 2024 11:44

Thanks for explanation. I think this is how it works but I have to observe. For what I can tell now is that I simply cannot run my radiators under 40C if there is +5C outside since they are not able to output enough heat (indoor temp is 22.5C). So it happened that I’ve set 23C and at given LTW it was not able to achieve 23C because it has short cycled every few minute. BUT, then I’ve change to 22.5 and it was finally turned off by thermostat so I guess now it will wait until temperature drops to 21.5 to start heating again ?? This hysterezis of 1C feels a little bit to much but I guess if I set it to 23C it will stop here and goes all down to 22 when it starts again.

But this itself won’t solve the issue. Another issue is thermal characteristics of my K2 radiators. So I’ve change the curve like this which could help a lot with heat transfer so the thermostat can shut down the pump before T1 and T2 is too much or too low difference.

Also my PWM cable arrived so I really hope this will help in efficiency a bit since it can regulate the flow from 7 to 16 liters per minute. Actual it’s fixed at 9 lpm which is not sufficient in most of cases.
I’m going to connect it so pray for me these adjustments help to run in longer cycles

Ian, could you please tell me what this settings mean exactly and what the difference between pump1 and pump2 and what means it there is no pump at all only on or off.

Ian_Calderbank · 24 January 2024 11:52

user manual page 28 and 29

Michal_S · 24 January 2024 12:03

Thanks, will have a look.

BTW, do you know how to connect this PWM cable ? It has 3 wired but PWM terminal has only two screws. So I think I will connect BROWN cable to PWM signal and BLUE cable to Reference (GND) but where to connect the BLACK wire ?

Ian_Calderbank · 24 January 2024 12:09

one is a return signal I think which you don’t need. can’t remember which is which. plenty of info available if you get googling.

Michal_S · 24 January 2024 12:13

Yeah, seems BLACK is output signal from pump so i will keep this disconnected.

Or is it vice versa? Do I need to connect signal input to the MIM or Signal output ?

Michal_S · 24 January 2024 12:28

@Ian_Calderbank Sorry for bother again but want to double check, if this is proper terminal to connect ? It’s a bit chaotically written in manual.

UPDATE:
OK, connected like this and seems working

glyn.hudson · 24 January 2024 13:31

I agree, it’s a shame the hysteresis is not adjustable. But I can’t see an option for this. 1C of hysteresis does not bother me, this makes for decent length runtimes.

Here’s my video about my heat pump:

Installation:

Performance:

Interesting, mine defiantly has a 1C hysteresis. It’s quite possible there are differences between different firmware versions. This is my indoor temperature as measured by the controller, I’m reading the modbus output.