Samsung Gen 6 8kW Efficiency

[SarahH (Sarah Hanson)]

Hi Arne, and thanks for the data dump

But I think I see the problem. It appears that you are looking at long term data (over a day or a month) rather than instantaneous readings, which is what CoP calculations should be based on.

I’m not familiar with your Kamstrup, so here’s what to look at step-by-step on the MIM-E03EN display to calculate your “real” CoP. The ASHP works hardest when first turned on, and when it’s cold outside, so pick a frosty day for your calcs, then:

1. Measure the outside temp (Ta) when your ASHP is about to start, with DHW disabled. (This assumes that you don’t run the ASHP at night except for defrost).

2. Once the ASHP has been running for 5 minutes or so (to get circulation settled, but before your ASHP outlet temp hits Water Law - probably half an hour later), make a note of the following (the data vary quite quickly with time so gather them as quickly as you can so they are self-consistent. If you haven’t used Service Mode much, have a practice to minimise the time between each screen).
   a) In Service Mode / Indoor Zone Option / Indoor Zone Status Info / Flow Sensor get the circulation flow in lpm (litre/min).
   b) In Service Mode / Self-Test Mode / Self-Test Mode Display get the Water Inlet & Outlet temps (Tw1 and Tw2). Note that these are only reported to the nearest degC. You can get a more precise water outlet temp from the Zone display.
   c) In Settings / Energy / Energy Usage / Instantaneous Power get the ASHP power in kW.

3. You’ll need the density (kg/litre) and specific heat (kJ/kg/degC) of your circulating fluid at the average of Tw1 and Tw2. These are readily available on the internet (they both vary slightly with temperature.)

4. Calculate your ASHP heat generation from Q = m * Cp * dT where m is mass flow (in kg/s = lpm * density in kg/litre / 60 to convert minutes to seconds), Cp is the specific heat (kJ/kg/degC) and dT is the temperature rise in the ASHP (Tw2 - Tw1, in degC).

5. Divide this heat generation by the instantaneous power to get your CoP.

6. Compare your calculated heat output and power consumed with the numbers from the Samsung Data Book at your measured ambient temp (Ta) and outlet temp (Tw2).

This is very easy to spreadsheet, but I’ll post one if you need help.

Let us know how you get on…

Sarah

[CoP (Pab)]

Thank you!

[marko (Marko Cosic)]

It would help if the installers can sketch (draw) how the pipework runs.

RA-G valves sound good.

The buffer vessel installed in a way that “adds volume” to the pipework loop without providing any way for water to “bypass” from the outlet if the heat pump back into the inlet without going through a radiator sounds good.

The item in the centre of this photograph is potentially problematic:

That is a bypass valve that will allow water to bypass the radiators. It should not be present.

[SarahH (Sarah Hanson)]

Marko that looks like a pressure relief valve (PRV). You may need this if you have separate zone valves for DHW and CH which can both be closed (if no demand for either). Your circulation pump may have “run on” for a minute or two after demand stops (to keep the ASHP happy) so a PRV may be installed to prevent low flow trips. This is poor engineering practice (PRVs are for emergencies, not routine use). We had ours removed and the 2 zone valves replaced by a single 3-way valve (which is always open via the buffer tank).
Sarah

[marko (Marko Cosic)]

They’d term this an auto bypass (for differential pressure) rather than a pressure relief valve (for excess static pressure)

It has no place in a domestic heat pump setting. Or any domestic setting since the advent of condensing boilers that modulate for that matter!

A P&ID (or for translation purposes - a drawing showing the routes that the water can take from the heat pump back to the heat pump) showing what’s going on will be helpful to rule out he balance of the installation as being at fault.

[Ian_Calderbank]

LLH = Low loss header. Sorry my fault for using acronyms too much. But it sounds like from your explanation that you have a tank that has been configured as a volumiser (one pipe in, one pipe out ?) as part of a single circulating loop that goes through the radiators and the heat pump. so you won’t have an LLH. That is a good thing. But it really is worth trying to draw a diagram . Just follow the pipes and draw lines on paper . But professional installers should do this for you.

One other way to confirm the topology: how many circulating pumps do you have / what are they circulating? A single loop system will have only one pump on the heating. I can’t see any in your pictures.

real time monitoring; read here to start with
https://docs.openenergymonitor.org/applications/heatpump.html
and then ask for help via [email protected] they are helpful guys.

as both marko and sarah have said you have an “auto-bypass” valve between the flow and return pipes. that creates a shortcut that some water will prefer to take over going round the radiators. This reduces efficiency. Provided that your radiators are always open (no TRV’s) then this is not needed , it should be removed and the shortcut blocked off. your installer needs to do this as part of troubleshooting your low performance.

[marko (Marko Cosic)]

It MAY be doing very little, if anything, if the radiator “circle” (we would say circuit) has less pressure drop than the auto bypass is set to.

It being there at all is a question mark that says “let us just check there is nothing unexpected on these circuits before we look too close at the heat pump”

[Madsen68 (Arne Madsen)]

Hi Sarah

Thanks for the very detailed explanation, which even I could read

The reading I get - which I still is very uncertain off, is around 3,28 CoP. (1900 W)
The databook shows at 2 degrees 8/1,86 = 4,3 - so missing around 1…
I have 4,3 degrees at the time I took the data out.
Outside temp: 4,3
Flow: 17,8 l/min
Inlet: 33
Outlet: 38
Consumed power: 2400 W a few seconds later it was 1900 - then back to 2400 and 1100 and so on…
At 2400W - CoP is 2,6…
I use only water…

When it comes to SCOP I run around 2,32 - period is 14/2-23 to 9/12-23 - So allmost a full year - the next few month will only drag the SCOP down a bit. Listed SCOP at 40 degrees is 4,15 - here I am down on allmost 2 and I do net even hit the 40 degrees in outlet temp.
This is the inside measurement of the Samsung (Production/Used)
Total usage of kwh compared to my readings on the kamstrup production and total Power readings, I get 2,18 - the 0,14 kwh difference goes to pump, system etc.

This is basically my frustration and my therory is that the system is having a fault with the R32 - Missing some, or to high pressure in there…

[SarahH (Sarah Hanson)]

Hi Ian.
I absolutely echo your (and Marko’s) plea for an installer P&ID at installation. This should be an MCS certification requirement IMHO. It was the first thing I drew up after my installation. As a result, I found that my installer had 1) routed the DHW coil outlet via CH buffer tank, so rads got warm even in summer (convection) when DHW required, and 2) switched ASHP inlet/outlet connections (reducing ASHP efficiency).
You need a Chem Eng degree to follow the ASHP set-up details, and a partner qualified in Control/Electronic Eng. Luckily for me…
Sarah

[Madsen68 (Arne Madsen)]

Hi Ian

Correct - it works as a volumiser, before I had a Circulation pump and the Buffer worked as a buffer.
They made this reaarangement of the system and mounted the PRV (Got this acronym :-)) and set the Buffer as Volumiser. So circulation of the system is done by the internal circulation pump of the indoor unit from Samsung - also where the MIM is installed.

Schemaic is uploaded

[Madsen68 (Arne Madsen)]

I hear you - I have no proffessional skills to explain why its there - but it is. Allthough I am quite sure it does not open - I have not felt any heat go from the outlet to return. I have plenty of flow in my system which I secured before the installation…

[Ian_Calderbank]

good diagram. thats all we need. as marko says, its more likely that performance issue is down to a system design problem than a “heat pump itself not working properly”, in 99% of cases discussed on this board it turns out to be the design. so to eliminate it from being a potential cause of loss, the bypass needs to go.
I really would recommend setting up regular automated monitoring, you already have the heat meter so a lot of the hard work is already done. then you can easily see what was the COP for X period. But much more importantly it’ll tell you if the flow rate and temp were steady and consistent, or if cycling is occurring, or some other instability.

[Ian_Calderbank]

yep, the engineering /technical degree or similar is a strong common factor for the people trying to get the best out of HP’s on this forum . that’s true for myself also. your installers errors sound rather basic.
I think Arne Madsen said they’re based in Denmark so I’ve no idea what the equivalent of our MCS is there, I do hope its not worse than ours

[SarahH (Sarah Hanson)]

Good work Arne.

A couple of other observations before you call in the lawyers…

1. Your measured ASHP heat generated (6.1kW) is only about 70% of the Samsung table at your Tw2 and Ta. Assuming that your flowmeter is accurate, this suggests that your ASHP compressor is not running at full speed. Based on my own observations, the compressor should be running at full speed until Tw2 reaches ~2degC below its target temp, then successively reduces speed to about 50% as target temp is approached, then cycles at this reduced speed (off at target temp, back on at [target temp - 2degC] as heat is dissipated from your radiators). Could your Tw2 target temp be about 38degC? If so, this might explain your reduced/varying compressor speed. (Your Tw2 target will be set either by Water Law or manually depending on your setup.) It is also possible (though unlikely) that your installer has enabled Quiet Mode which reduces compressor/fan speed (thus noise and ASHP capacity).

2. The variability of your power consumed is a puzzle (though the average of the numbers in your post is similar to the Samsung Table power). Per the above, compressor speed (thus power) should be fairly constant until you approach target Tw2. One explanation is that your compressor is hunting (rapid cycling if flow/temperature instablilities confuse the control algorithm). You could perhaps test this by increasing water circulation rate (if you can). [Your flow is 30% lower than mine for the same 8kW unit.]

3. If you have a third party room thermostat on your CH (i.e. you do not use the MIM-E03EN internal stat) then its internal settings may not be fully compatible with the MIM controller. [My smart Honeywell was sending “room temp setpoint nearly reached” signals too frequently to my MIM, which confused its internal algorithm into reducing compressor speed. With Honeywell’s help I reset its internal settings and now all is well.]

4. When you do your calcs, don’t forget that ASHP power consumed increases (so CoP decreases) as circulating water warms up, even though (for the Samsung) heat generated is fairly constant. This is why it’s important to take your readings as quickly as you can (before the temps change).

My suggestions:

1. Temporarily increase your Tw2 target temp (to say 45degC) and repeat your data gathering/calculations, knowing that your compressor speed should remain at maximum.
2. Increase your water circulation rate to about 25lpm if you can, and repeat the exercise.
3. Check that Quiet Mode is disabled (Settings screen).

I await your results with interest…
Sarah

[Madsen68 (Arne Madsen)]

“A couple of other observations before you call in the lawyers…” 

 I wont call them….yet 

1. Yes, Target Tw2 is around 38 degC and I use Waterlaw/Weathercompensation. Do not use Quiet mode.
2. I have no control over the flow – But today, when the test was made – I got “normal” flow, compared to what I am used to have. (Around 22-26 l/min.) I have no way to control this – its controlled by the ASHP
3. I use the MIM, so no 3rd. party sensors attached - We have discussed this as a solution to bypass the softwares delta t. Should be able to set the MIM as a temp controller itself, when that is done, it will be possible to control the Delta T – I was told…. But they went for another solution. Before Software upgrade, the Delta T was at 1 as default – not possible to change. As I have understood, the ASHP is sensing the temp. is 1 degC below target, then the pump takes it as a signal that heat is needed and starts. Safety start up, last about 6 minutes and in that period the temp has already been raised above the target temp. so ASHP now shuts down immediately after Safety start seqence is over. So they had meetings with Samsung, who released a Beta software for the unit, which is fixed at delta t at 5, so now this unit should go 5 degC below target before it starts and 1 degC above before it stops, but I cannot see any difference in how it runs, after the upgrade – Is it normal at outside temp at 4-5 – it runs 20-21 hours out of 24?
4. I am quite aware of that when it comes COP – and I get the following readings:

I have powered down the ASHP and it has been shut down for about 3-4 hours – a bit chilled inside – temp. drop at around 2 degC. I started up the unit, NO DHW. Just to make sure my pump on the Shunt was not making the flow go up and down, so to be safe, I have closed valves for shunt for the Floorheating system, during these test.

After 2 minutes power consumption at 400 w

After 3 minutes power consumption at 1400 w

After 4 minutes power consumption at 1900 w

After 5 minutes power consumption at 2000 w

After 6 minutes power consumption at 2100 w

After 8 minutes power consumption at 2400 w

TEST 1

The following is after 6 minutes:

Regarding Flow I get these readings during those 6-7 minutes: 12,9 – 9,8 and ends on 24,5 l/min. So that is what I take as thrustworthy, at that time I get 2100 watt and 35/29 – Outside temp is 4,9 degC

This looks like a CoP at 4,9 to me. Pretty close to Data book – so far so good……

TEST 2

Take measuresment again after 18 minutes:

Flow 23,8 – 2400 watt – 39/33 – outside temp is still 4,9 – So this hits 4,17 – so it is flattening out.

TEST 3

After 30 minutes I again take the data out – looks like this:

Flow 23,1 – 1200 watt – 36/33 Outside is still 4,9 so this hits 4,04 CoP

So CoP is more or less good at startup, but drops during time of production, although Inverter works at 100% on all readings in the menu.

Maybe some important info: I also have to mention that this have been going as from day 3 – why day 3 – Because at the first day, during first start up – I was reading CoP at around 4 in the panel – I know it is not the correct CoP – but it was making about 4 times more heat when input was 1 Kw – This was done in MIM panel – Since then I have not been able to get above 3 in the panel – not even today – when the CoP was measured at 4,9 – The panel gave me 2,86. And that number is very close to what I call my SCOP value…… Performance over time – I have attached a picture with Scop over time “from/to” in periods – My overall Scop is 2,18 – I have used 1856 kwh and produced 4042 Kwh – Reading from my Power meter and my Kamstrup. Also a drawing of my system is attached here

My own little conclusionist  inside my head thinks 3 things:

• PRV needs to go as step one
• R32 amount and pressure needs to be checked
• If step 1 and 2 does not make a difference – add a Buffer at approximately 200-300 liters. – Not the 80 liter I have now – I asked them if that buffer size was enough, and they confirmed that, before install, now it not even mounted as a buffer….

Or are you at a completely different place in solution to gain CoP/SCOP

[Madsen68 (Arne Madsen)]

Update: Made another measurement this night for CoP which landed on 3,75 - a little temperature raise to 5,2 degC

need to get that system to log with emoncms…

[Madsen68 (Arne Madsen)]

Noticed a little difference in readings in the MIM of the ASHP.
Same color is similar outside tempeture median. Have no readings on flow these days…

And just for the record… I really just want to understand why the ASHP act as it does and offcourse, if I find something during that way, that can optimize the performance, then lets do it.
But in general, I just wants this to work, best as possible
And I am really stunned over the help I get here, just a bit sorry to have partycrashed CoP Pab´s thread - sorry @CoP

[SarahH (Sarah Hanson)]

Good morning Arne.

From the data you have presented, I would say

1. I’m impressed with how fast you have got yourself up the learning curve - it’s taken me 5 months to get where you have got in a week (I shall be coming to you for guidance now… ),

2. Your readings as your system warms up are very similar to mine, so I think it unlikely that your ASHP has a fault (but no harm in having the R32 checked if your installer will do it),

3. The reduction in CoP as Tw2 rises is to be expected, of course, and I see nothing in your data to suggest that your system is underperforming significantly (yours is running at better CoP than I get, but that is because I have a higher Tw2 target temp - about 45degC - because my partner complains if the room feels too cold),

4. Personally, I don’t consider SCoP performance to be so important to worry about, as there are many external factors such as thermal inertia of the house (thus duty cycle rate) which affect performance over longer time periods. My main focus has been on minimising daily running cost. For example, I use less power overall if I just run the ASHP during the daytime, even though the first couple of hours’ operation costs are higher.

5. My only complaint about Samsung is that they are very protective of their controller algorithm information. I’ve had to resort to “reverse engineering” of the various interactions in order to optimise ASHP performance. That is why discussion groups like this are so useful - I hope you will continue to offer us any new insights (good or bad) as you gain experience…

Sarah

[Ian_Calderbank]

50L is the min system volume so your current volumiser should be more than enough
About running 21/24… for my house yes. It depends on your house - your heat loss, and does the heat pump modulate to a low enough level to match the heat loss. if they do match, then it runs constantly, which is what you want.
example: here’s my system yesterday, up to 10C external temp, ran continuously for 16H.

when you talked about “DeltaT” are you referring to the change in actual room termperature with respect to the target temperature set on the controller? just checking because usually DeltaT is used to refer to difference between flow and return temps in the heating circuits.
if your house is getting up to target and overshooting so quickly that could be an issue. Getting real time monitoring (emoncms) will really help - you can immediately see if you have any kind of cycling going on.

here another example from my system again: it wanted to heat at 3am. At this time the radiators in bedrooms are shutdown (by programmed TRV’s , because we like cool rooms for sleeping). this means the emitter area in rest of house isn’t quite enough for stable running. So note the resulting COP is not as good at the daytime, and there are some cycles. But I tolerate it, because night electricity is cheap.

once you get emoncms setup all this is a few mousceclicks away.

the COP numbers you posted for the last month don’t look at that awful to be honest when it was cold, you’ve got some cold weather there. I don’t know what your climate is like where you live but in the damp UK , a heat pump would be spending a lot of time in defrost mode at those temps, which really hits COP. Do you see it frosting up? sending clouds of vapour into the air (roughly every 45-90 mins) as it self-clears the ice?

edit: one more thing

your diagram of your house with radiators on it. It says “effekt 70/40 20C”. I would interpret that to mean that the wattage shown is for that radiator with an input water temp of 70, and output water temp of 40C, and a room temperature of 20C? I could be wrong but thats how I read it. It is quite typical for radiator manufacturers to quote radiator performance with “boiler” type temperatures.
The actual water temp is of course a LOT lower than that, which massively reduces the radiator output.
Do you have actual output numbers for your radiators at the actual water temp that your heat pump is running at? If not, if you can confirm that those are “boiler” based output figures, I can guide you to some formulas that will downgrade the to get the “heat pump low temp” figure.

[Madsen68 (Arne Madsen)]

Hi Sarah

Thank you so much for your help and very detailed explanations

1. Thanks - I really would like to understand 100% what is going on and why
2. I will, still feel there are something spoky with it…
3. That sounds great that I run better CoP than yours, but I still find it very strange that in the midlle of November under the same conditions I get readout on MIM Panel to be around 2,59 - today I get 3,73, which I woulkd be more than happy with, if it turns out its stable…(Still know it will go up and down with the outdoor temp.) So I monitor the bastard heavily
4. I was promised before installation that our Powerconsumption would be around 4000-4500 kwh - I have reached 4000 kwh and still misses 2 full (COLD) month to complete a full 12 month period, so I can problaly add another 2000-2500 kwh in those month, thats why I try to learn, understand and maybe solve where the lack of performance is, compared to the numbers… I used 1560m3 of Gas, which equals to 17.000 kwh heatning need for the house - Scop then should be around 3,75-4,25 - As mentioned before - I have not measured any CoP/Scop above 3 at any time and currently CoP for the period from 9/6 to 9/12 is exactly 2,18, allthough the past 2 days are different in the readout on the MIM.
   That shows me that the ASHP is OK, like you say, but I need to understand why the performance has been poor for so long, Could be the PRV that making the trouble so something being triggered so flow is low…
5. Agree, I was told they do NOT make special software for UK - DK or any other region, they only implement changes that are approved by the big distribution countries, allthough this Beta software that I have was made because of the challenges with our installation here.
   I really miss a Menu to set up On/off on timebase - In DK we have very high taxes in between 17 and 21 at night, so would have been perfect to set up the ASHP to shut down in that period, or at least some of the time, just like yopu do - shut it off at night. Is that done manually?
   And yes, you and the otherguys here made me see “the light” Thanks