yes we may be about cross purposes - I mean long periods of steady state. yes I’ve got more than 15 mins (I am out of contract and looking for next one - looking at this is far more interesting than talking to recruiters and walking the job boards and Linkedin…)
I don’t understand some parts of your spreadsheet I’m afraid , in particular K-M and O-P. you may need to spell those out for me, how are you inferring a compressor speed ?
I can see though that E is the calculated heat output based on DT and flow rate. Based on that having an average of 4.85kw (E26), your system is working at more than 50% of its rated 8kw capacity over this period. So not surprising the compressor would be working at 50% or more during this period.
also your room temp increased by 3C so the HP was putting more heat into the house than the house was losing. My point is about a long time period (hours) when the system is maintaining the room temp at a steady level - are you able to achieve that ? you mentioned about your high LWT setting, maintaining that high LWT will be why your machine is working quite hard (column F is the electrical load ?).
Columns K-M come from the capacity table in the Samsung EHS Technical Data Book. (Duty is constant for LWT up to ~50degC at any given ambient temp, but power increases with increased LWT and I simply curve fitted these latter numbers.)
To estimate compressor speed I divided my measured power and calculated thermal duties by interpolation of the Samsung published numbers at full speed. I assumed that both capacity and power varied linearly with speed. (The only scroll compressor datasheet I have - a Daikin - indicates that this is a good approximation.)
Yes column F is the controller display of ASHP power (i.e. excluding power to pumps and controller).
I take your point about the room still warming up, but the ASHP doesn’t care where the heat is going, whether warming a room or the environment. I deliberately chose a time period for the test when the roomstat didn’t stop demand, which would have upset what was otherwise a reasonably steady state.
Finally, I have my weather compensator set high because I am not yet convinced that “low and slow” would save much money in my case - I’m still doing the calcs .
Oh and good luck with the job hunting, though we do need you to keep up with your contributions here…
According to their marketing material, Samsung use BLDC twin rotary compressors in the gen 6 series, not scroll compressors. Apparently rotary compressors are cheaper and noisier than scroll compressors, which matches my heat pump!
My system is the Market Drayton one. The highest heat output that it has provided was just over 9kW and the lowest just over 2, but it won’t maintain that and cycles up and down with a mean of about 3kW. The electrical input does drop quite noticeably down to just over 400W with a peak of nearly 4.5kW , although normal peaks are about 2.5kW.
Roughly speaking the output modulates just over 2:1 but the input modulates 6:1.
ok, I think I get your method now. It seems probably reasonable as a rough-order-of-magnitude, and common sense says the numbers you’re getting are about right.
your power consumption numbers are what jump out as high to me. which will be down to the high LWT.
In steady state, my system sits at LWT of 36 (at the same ambients as your test) , power output around 4000W (no too dissimilar to yours), power input around 900W (significantly better than yours). system 71 does better than that and with even lower LWT . ah I see @billt the owner has contributed - thanks Bill!
My expectation would be that if you can run at a lower LWT, you can maintain the same output for a significantly lower power input: because we know (based on 2 other systems experimental evidence) that its possible for the compressor to work less hard than what yours is, for the same output. So doing the maths for what you need to do to your emitters to be able to run lower LWT, appears to be the key!
Thanks for the data, Bill.
Just for your info, this thread has been subject to “chinese whispers” and moved on from Gen 6 to EHS Mono Quiet, which do have scroll compressors.
When you say output and input modulation, I assume you are referring to heat generated and power consumed respectively?
Hi guys, I’m new here and glad I’ve found this forum. Just recently I’ve got AE080BXYDGG/EU installed and I would have some questions for some of the experts here. First just a backround about the system. I have house with 2 floors, standard radiators type 21 (10x) and 2x ladder radiators in bathroom. Heat losses are around 4.5KW at 0C outside with indoor temperature 22C.
So here they’ve installed and pump - it’s a direct installation connected to the circuit where an electric heating was. No extra stuff. Only a water pump installed at output. Grundfos Alpha 1 25-60.
So now the first problem was that often I was getting flow error because flow was lower than 7 lpm. This happened because thermostatic valves at 1st floor was mostly closed and some on basement as well so the flow was low. The heatpump was cycling every 15 minutes sometimes and was really bad. So I’ve removed TRVs and fully open radiators with lockshield valve. This helped much but still sometimes every few hours the heatpump stop for 5 minutes. I’ve found it is because installers forgot to connect PWM cable from the water pump. Would you believe that ? So the heatpump requested to lower the flow and nothing happened so after some time it stopped because temperature difference was very minimal.
So here my questions:
Is the PWM regulated water pump crucial for this heatpump. What are consequences of using a fixed RMP water pump, a.k.a. PWM cable not connected.
Until they connect PWM cable I’m running the pump at max. and with all radiators fully open it shows max. 16 lpm flow. Do you think this flow is sufficient for this heatpump ? HT Quiet has minimal flow of 7 lpm but I guess old generation required minimum 22 lpm which seems pretty much to me therefore I wonder if 16 lpm is sufficient or if I should use maybe more powerful water pump ?
Do you know what is the minimal power input this heatpump (8KW) can run on before it switch off the compressor ? I’ve seen 1.0KW in wired controller but can it get lower ?
For now I’ve measured COP 2.75 for roughly 45/40 temp difference with -1C outside which is roughly 0.5 less than in the sheet. I think those COPs on paper are little bit overrated and one should expect always a lower effectivity.
1… with the pwm cable, it’ll slow the pump down to try to preserve the target DT, which can make the operation more stable . although its not guaranteed, the issue could be something else, perhaps simply cycling because heat is going out of the emitters slower than heat going in from the heat pump
2. The min flow rate will be on the manufacturer spec website. can’t remember if its 7 or 12 for the smaller units. 16 is definitely enough
3. I think people have been able to get the 8’s to run at around 2.5-3kw of output . Not sure what the input drops to but I can run my 16kw at 800w input, so better than that should be do-able. have a look on heatpumpmonitor.org there are a couple of 8’s.
COP in -1C will always likely be affected by defrost. If you setup monitoring of your system like many on this forum, you will be able to see the difference between “running COP” and “overall COP including defrost”
No, it’s not crucial, you just need to disable it in the settings (set FSV 4051 to off) to avoid the errors. I ran my Samsung 5kW HP with a fixed speed pump for over 12 months and got a SCOP of 4.3 eg. Emoncms - app view dashboard.
My HP had older Samsung firmware which did not support PWM pump, in the past few months I’ve updated my firmware and got the PWM to work. The Pump now uses a few 10’s of Watts less, I’ve not noticed any significant difference in the COP. But if you can get the PWM to work it’s preferable. Does your pump have a PWM input? Do you have the cable for it?
You need 23 L/min to get 8kW at DT5 assuming no glycol, you need more flow if you have glycol since glycol reduces the specific heat capacity. 16L/min will only give you 5.6kW. If you’re only getting 16 L/min with the system fully open, you either need to upgrade pipework to reduce pressure loss or install a larger pump to be able to get the full output of the heat pump. However, there’s a good chance that your heat loss is lower than calculated and 5.6kW will be enough
The minimum power will depend on the outside temperature, looking at other 8kW Samsung HPs on https://heatpumpmonitor.org/ it should go down to about 450W. The minimum heat output seems to be about about 3kW. If your house requires less than 3kW, which will be the case when it’s mild outside the HP will cycle, this is nothing to worry about. Samsung doest seem to lose much COP while cycling.
How have you measured the COP? I’ve found the Samsung onboard monitoring to be very inaccurate, mine underreports heat by 20% and over-reports electricity by 5% compared to OpenEnergyMonitoring using MID approved meters.
FWIW I’ve been pleased with the performance of my Gen 6 8kW (apart from the poor CoP at low temperatures).
We recently had a period with the outside air temperature was about -7C. The peak power was about 9.3kW and the Cop 2.4. The spec says 7.35kW and 2.43. Generally I’ve found that the output power exceeds the spec and the CoP matches the spec quite well.
Flow rate for the Gen6 8kW is given as 7-48 l/min.
Thanks for reply. I will try with PWM but I only wonder why the system is shutting down when “water law” is selected. I thought it’s because the flow it’s either too low or just to high without PWM modulation. I wonder how the heatpump knows when to stop heating ? If I control by temperature on thermostat it’s clear but with water law I’m not sure. It is supposed to heat all the time ?
Yes, it’s 7 lpm but problem was that with some TRV closed it felt under this limit and error was thrown. Good to know 16 is enough but this is with all TRVs fully open which is not very desired since I would like to control temperature at least a bit.
Wow 800W is great, but to be honest I haven’t see this dropped below 1000W on this Samsung yet so I wonder if this is the lowest input it can’t handle. It’s scroll compressor. Problem is that they will use 3.7KW compressor in the whole range from 8KW - 14KW so probably the low limit is same with even 14KW units which is a little unfortunate.
It has been around 0C here past days but frankly it hasn’t defrost once! I was pretty surprised but fins were dry without any ice if there was 0C or -5C. It must have been really a dry air here.
What setup everyone is running to have such nice graphs? I have Shelly EM3 to monitor my whole house but I l like this one.
better to keep your TRV’s open (or removed) and control temperature with lockshields and getting the circulating water temperature right. you need all emitters that you can open with a heatpump.
your system could just be shutting down because its got warm enough. No it won’t heat all the time - if the WT’s get high, it will shut down for a bit. there’s a good description of the cycle behaviour from sarahh on here somewhere. its not necessarily a bad thing: its how the system works when its mild. If its doing it when its cold, then something could be wrong.
flow rate - glyn’s point is important, if 16 lpm is all you can get due to your pipework, you won’t get the rated output from the system. my reply was relating to min flow level to avoid an error, I thought that was what you were asking.
defrost - thats good. quite a lot of us are uk based who are constantly getting defrosts when its cold due to our damp uk climate
compressor - I don’t know.
monitoring - you can either install an inline heatmeter and electric meter, look at the openenergymonitor bundle with raspberryPI. Can’t help you more on that because its not what I use but most on here do. Or, you can use what I do, install the samsung modbus module to pull the flow rate +temp data from the unit itself into a suitable compute platform (I use home assistant). plus an electric meter dedicated to the HP. These monitoring systems REALLY help with troubleshooting and tweaking to improving performance.
@glyn.hudson thanks for reply. That’s is a very nice SCOP. What is your climate and do you have floor heating or radiators ? Can imagine with floor much better COP can be achieved.
My problem is that if I keep it running at max. speed the temperature difference is lower an lower so it want’s to slow down a flow a bit to increase it. Type 21 radiators are not ideal and Type 22 would do much better I would say.
Yes, pump has a PWM but contractor does not have a cable so it has setup it for radiator heating which uses some partial pressures to regulate the flow. No idea how precise it it. But I will buy a cable and install it. It costs 20 eur so not a big deal.
23L no way for my system I’m afraid. I cannot change pipe work so faster pump is probably the only option ? This is already with all radiators open so I can’t get more with current pump. But one question here. Does the flow increase with raising temperature ? I’ve measured this flow with 40C water. Could it be that with 50C the flow is 20 or so ? What about pressure in the system ? Now I have around 1.2 bar, will it help if I increase the pressure a bit ? My heat losses might be definitely higher if there is -10C outside unfortunately.
Regarding minimum power this is interesting but I’m a bit worried that this one HT Quiet can’t go lower than 1KW. It uses the same compressor as his bigger brothers 12KW and 14KW units. It definitely requires less. At 10C it needs maybe 2 - 2.5KW.
COP only from I read for the last night from onboard monitor. But if it over-reports electricity this is quite good
I guess will have some fun with tweaking this thing. I’ve bought 8KW unit especially because I wanted it to get it as low input as possible. Otherwise I would buy probably 12KW unit which has better COP damn it. It should be mandatory for manufacturers to sate also minimal power input, really don’t know why this is not written there. But I was not aware that minimum power input depends on temperature. Isn’t is supposed to be constant ? I understand that output depends on temperature but input ?
UPDATE:
For this “(set FSV 4051 to off)” - where can I update it ? It’s possible on remote controller in field settings or this needs to be done on control kit ? Thx
UPDATE2: Now I’ve checked your stats. How’s possible that you have COP over 4 at 1C ?? I’m hardly getting 3 at 38/34. Can’t get that. What temps do you use ? You have a floor heating ?
For now I don’t know if it’s the piping limiting the flow or the pump is not strong enough. I have Grundfos Alpha 1 25-60 which works up to 6m. My 1st floor radiators are 5 - 6 meters above heat pump. Is there a way how I could find what is a limiting factor ? I have 3 circuits. The main pipe diameter is 28mm and the circuits are 22m. Do you think it’s limiting factor or I can get more flow with stronger pump ?
When I had AC to heat they defrosted much more but could it be that simply the air is dry. I need to observe but the fact is the weather here is nowhere that wet as in UK.
This approach you have I like. I also use HomeAssistant with Shelly 3EM to monitor electricity but this solution with PI looks interesting. I have one spare Pi in a pocket. Can you tell me more how this is configured or where to buy the the hardware to make this running ?
I appreciate that.
Do you also know if e.g. 20 start/stop cycles per day are problem for this heat pump ? Or it’s OK.
One more update maybe you can help with pump power. I did measurements and it gives 10 lpm at level II. And at III. (max. speed) it gives 16 lmp. Do yo think with bigger pump it can get higher ? From These numbers I think it could or?
Also do you know if there is any difference if they did not install the pump on return but on outlet pipe ? They said there is n difference but wonder if it can have any impact on performance. Usually water pumps are installed on the return pipe so I don’t know. The pressure is ~1.2bar, do you think it’s OK or can it have some impact on flow ?
I’ve just check the flow needed for 8K and dt=5C and it was around 23 lpm. But then I calculated for dt-10C and it was required half the flow around 11 lpm. Really a 5C difference has so dramatic impact on required flow rate?? In that case I think the heat pump could maintain a bigger temperature difference to keep with the 8KW heat requirement if it sees it can’t achieve a higher flow rate ?
Many thanks.
@billt Do you have HT quiet version or regular. Do you have data here on OEM ? 2.4@-7C is very good. Before I’ve removed TRVs to fully open the system I was getting around 2.3@-5C. Now I need to check but still I’m bit bellow paper specs. Do you know what is the minimum power input for your unit ? Guys here said around 400W but I’m worried with mine I won’t get under 1KW which will cause some problems in spring.
as I said, I didn’t use the heat meter + PI approach. others can advise.
6m “rated head of pump” is not about height of house. that is a common misconception. Its the maximum resistance to moving water of the circuit, that the pump can overcome at a relatively low flow rate. At 16l/min the head that the pump can deliver will be somewhat less than 6m. the grundfos pump curve will tell you. depending on the current position on the pump curve you may well be able to get more flow with a stronger pump, but its always worth looking at the circuit design first to see if resistance can be reduced. Not just pipe sizes - what are the valves and other components it passes through, all have a resistance.
speed III will be full power so if you need more than that you need to change something.
DT . its not that the difference is 5C . its that you doubled it. In which case yes, you’d half the flow rate. simple maths. But it doesn’t work like that in practice, at least with these HP’s, you can’t just set it up for DT10 and hope it works, it won’t work. It won’t be comfortable and stable for long periods unless you can build a flow pipework for 5C DT (or less). It really likes to have a high flow rate . mine runs best at 4C DT. you have to build for high flow rate.
air in system can be a flow rate factor. do you have an air separator? 1.2bar seems normal.
personally I wouldn’t be unhappy at all about 2.3 @ -5 with flow temps in the 40’s , thats what I was getting when we had very cold dry weather in UK last week.
Many thanks. Can you give me some hints where I can study approach you used ? I’m open to all ideas either yours or Pi one.
Yeah, 5-6m is probably at the top most radiator but I have pretty long pipe from HP until where it connects to the system. This distance is around 10m so maybe here are some pressure loses as well.
But do you think increasing the pressure to e.g. 1.5 bar could increase the flow ? It’s a good points with valves, do you think if I remove TRV valves completely I can get more flow ? Can you see an issue with pump not place at the return ? Or it does not matter where it is in the system ?
Yeah, problem is I can’t rebuild the piping, I would need to destroy half of my house lol.
So for you -5 is a very cold weather ? :)) There were times where we had here -20C like in Russia lol. But those times are gone and now we are lucky if we have some snow for a week or two Average temp in January last year was 2C lol. But there are few freezing nights few times a year.
Seems there is lot of fun with these HPs to tweak them to its best.
again, 6m height is irrelevant. water goes in a circle. what goes up comes down, effect of gravity is neutral. but a long pipe can indeed be an issue if its not fat enough, high friction loss causes the low flow rate.
by valves I also mean things like diverter valves or zone valves, through which all the flow passes. if they aren’t big enough they will slow flow down. increasing system pressure will not help.
some maths:
here is your pump performance curve. at that 16l/min flow rate, if your pump is flat out, then you’re using 5.23m of head.
head loss is 5.23, q=0.96 (convert between m3/h and l/min) , gives k = 5.67
to get 23l/min, q=1.38, h=k*(q^2) solution is h=10.8
To push 10.8m head at 23l/min is going to need one big bad expensive m*****r of a pump. its not going to be anything domestic size or price.
suggest you take a serious look at your pipework, something must be constraining it. draw it, including every component it passes through. check filters and all that kind of thing.
-5 is indeed very cold for southern part of the middle of england where I am. what country are you in?
Did you see this unit in person or why such hard statements ? Well, I didn’t see many heat pumps but I saw LG Therma V monoblock and hey, this is noisy as hell. HT quiet has “Quiet Mark certification” so it hardly got it for nothing.
Anyway, I’ve just got this unit installed and I can tell you it’s very silent. Mostly what you can hear is the fan. At full throttle you can hear some noise but this is much quieter that my two split ACs I had before.
It’s still new to me but most of the time if it is not working as expected is the error in installation. There are so many aspects to fine tune here and you need lot of time and experiences.
Installers here really didn’t take care at all about the system itself, they’ve only plumbed in. They didn’t know this requires a water pump lol so what can one expect from such experts…
Anyway in terms of noise I’m pretty happy so let’s see how this works.
Can you explain this in more details to me ? Why compressor reduces from 100% to 50% and then turn off? It’s not able to go lower ? For know I was not able to determine the lowest power input this can run. It was max. 2C outside here and lowest I could see is 1.0KW in energy monitor but saw unit turned off couple of times. I did not have installed PWM and pump was running at very low flow so probably this was the reason. I removed all TRVs and max. flow I can get is 16 liters per minute. As I’ve learned this might be good max. until 6KW so probably I need to install bigger pump. I don’t know if this compressor can go lower or this is minimum input. That would be unfortunate because it would far exceed my heat losses during warmer days. I thought it can go lower like 600W or even less but probably not ? I saw that 12KW and 14KW units use the same compressor so I fear it can’t go lower.
I bought 8KW unit especially because I thought compressor can get as low as 500W but now I really doubt. Maybe when it is warmer outside I can see it go lower than 1.0KW but not sure. Problem is that I haven’t find this anywhere in the tech specs. There was only max. power input and that’s it. I thought that because it is only 8KW it can go lower…
You can add a PWM pump into the system so HP can control the flow rate in the system for optimal performance. I’m yet to try this because as I said installers forgot to connect PWM and didn’t disable in the control panel. So unit was confused. Now I’m testing with pwm control off to see if there is any difference. I found when flow was low around 10 unit turned off much more often. With flow 16 it turns off after 3 hours or so. Let’s see if disabling PWM change this behavior or not.
So how are you overall satisfied with this HP ? I’m still learning so I don’t have a clear answer now. I think modification to the system can help a bit to improve the behavior. But what I like actually is the noise. This is really very good and for me most important is I can’t hear it in the house. Either general noise or low frequency hum transferred into the house. This was issue with AC units I had before. Maybe we can talk more about this unit and exchange some experiences Cheers.
To be honest I don’t have schematics of this, from what I know it’s very simple. In the cellar there is a technical room where heating is connected. The main pipe is 28mm thick and from this pipe there are connection to 3 circuits where pipes are 22mm. In the system there is just one magnetic filter and flow meter with pump connected. All new. Nothing else. Those 3 circuits goes directly to radiators. So there is really not much I could open more. But question is if this pump is really undersized or if piping is the issue. I had electric heater before with pump running at minimum and it worked just fine. I don’t know what flow was there but obviously it was not an issue. What would you say for Grundfos 25-80. It costs 2x more but what flow do you think I could achieve with this one ? Sorry I’m not very good at reading these graphs yet. Do you think I could go over 20 lpm ? I barely will need such output because this would required -15 or -20C outside but I will try to draw it for you but I’m not that good at this
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