Help in raising the COP on my Samsung 5kw ASHP

[Suffolk peasant]

My first post - and only because I have had to admit defeat after reading and trying to fix my rubbish COP. I really have tried and it is not from lack of googling and trying things.

The ASHP is controlled by a gen 6 Samsung controller, it supplies DHW and DH with a once a week immersion boost.

I have DHW set to 47, and for heating 40.

I have gone through all the settings on the field setting system and apart from lowering the default HW and heating every setting is default.

 

Downstairs is UFH, upstairs is radiators [not used as not needed - open plan]

 

The mixer valve is set to 45 - I suspect it isn't entirely accurate as at 40 it doesn't deliver hot water to the manifold reliably.

The flow in the manifolds are such that there is a temperature drop of roughly 5 degrees across each of the circuits.

 

When I looked at the menu on the controller that that shows consumption and generation what I have indicated for the last week is

Consumption 124KWh

Generation 38KWh

 

Help - where do I look to get these figures almost completely reversed?

 

Hoping you can help.

[JohnMo]

49 minutes ago, Suffolk peasant said:

once a week immersion boost

Do you need to do that, do your own risk assessment. Plenty of information on here and heat geek website 

 

If you have a cheap mixer they are generally pretty rubbish is you don't deliver 70 Deg water to them. I ended up deleting the mixer and pump. Open it up fully and see what happens.

 

You really need to assess if you need 40 Deg flow? You either need weather compensation mode or a lower fixed flow temp. The lower the output flow temp from the heat pump the better the CoP.

 

Switch all immersion heaters off and see what happens.

[RobLe]

That COP is so low, that I think something odd is happening, as opposed to the usual high flow temperature at the ashp.  I think ostensibly it suggests an average COP of (124+38)/124 =1.3.  This may or may not include the weekly immersion use.

You don’t complain of a cold house; in this weather if the COP were actually that low I’m surprised the unit can actually warm the house sufficiently.

Has it always been like this?

 

Suggestions to try:

I note that 124kWh elec in a cold week is not insane - can you calculate your heat loss in kW, see how it compares to an hour of the generate+consumption at the design external temperature?

 

Fit an independent mid-certified elec meter to the ashp, and also a heat meter - more effort this, but will give a believable COP.  Eg opentherm.

[Beau]

1 hour ago, Suffolk peasant said:

 

 

upstairs is radiators [not used as not needed - open plan]

 

 

 

This is what jumps out at me. By not using the rads the UFH has more work to do so the flow temp through it has to be higher lowering your COP. The most efficient systems I read about have everything open so lots of water running at low temp to heat the place. 

 

Oh and welcome to the forum 🙂

Edited 15 hours ago by Beau

[DamonHD]

I do not think that 'everything open' is always right (formal paper https://www.mdpi.com/2071-1050/16/11/4710 - TL;DR https://www.earth.org.uk/To-Zone-Or-Not-To-Zone-with-TRVs-for-Retrofit-Heat-Pumps.html - discussion on the Heat Geek thread here), but definitely go for weather compensation: you do not need to run at anything near the maximum temperature most of the time and so WC will improve CoP and reduce cycling.

Edited 15 hours ago by DamonHD

[Suffolk peasant]

1 hour ago, JohnMo said:

Do you need to do that, do your own risk assessment. Plenty of information on here and heat geek website 

 

If you have a cheap mixer they are generally pretty rubbish is you don't deliver 70 Deg water to them. I ended up deleting the mixer and pump. Open it up fully and see what happens.

 

You really need to assess if you need 40 Deg flow? You either need weather compensation mode or a lower fixed flow temp. The lower the output flow temp from the heat pump the better the CoP.

 

Switch all immersion heaters off and see what happens.

I'll open it right up now and report back tomorrow.

I have the current manifold temperatures and see if they differ in the morning.

Edited 14 hours ago by Suffolk peasant

[Suffolk peasant]

1 hour ago, RobLe said:

That COP is so low, that I think something odd is happening, as opposed to the usual high flow temperature at the ashp.  I think ostensibly it suggests an average COP of (124+38)/124 =1.3.  This may or may not include the weekly immersion use.

You don’t complain of a cold house; in this weather if the COP were actually that low I’m surprised the unit can actually warm the house sufficiently.

Has it always been like this?

 

Suggestions to try:

I note that 124kWh elec in a cold week is not insane - can you calculate your heat loss in kW, see how it compares to an hour of the generate+consumption at the design external temperature?

 

Fit an independent mid-certified elec meter to the ashp, and also a heat meter - more effort this, but will give a believable COP.  Eg opentherm.

It is not a cold house - it is very small 60MSq on the ground floor, all open plan, MVHR to move air

The immersion makes very little difference.

 

With all the heating turned off my summer daily consumption is about 6KWh so I can remove that from the usage through the winter and it seems to be reporting correctly.

[Suffolk peasant]

1 hour ago, Beau said:

This is what jumps out at me. By not using the rads the UFH has more work to do so the flow temp through it has to be higher lowering your COP. The most efficient systems I read about have everything open so lots of water running at low temp to heat the place. 

 

Oh and welcome to the forum 🙂

The whole place is open plan downstairs and I have MVHR, if it is 21 downstairs it is usually 16 upstairs without doing anything - and that is fine for sleeping for me.

I don't think the UFH is working too hard, the temp in is 40 and it chugs along nicely.

 

[Suffolk peasant]

Thank you everyone - I just feel so helpless.

I did look at heatgeeks as a friend has used them, but the local recommended firms didn't appear too wonderful, and they weren't Samsung experts as far as I could see - and I am beginning to think they may need to be.

 

I want to exhaust all the control and flow settings before I focus on the ASHP itself.

[Beau]

17 minutes ago, Suffolk peasant said:

The whole place is open plan downstairs and I have MVHR, if it is 21 downstairs it is usually 16 upstairs without doing anything - and that is fine for sleeping for me.

I don't think the UFH is working too hard, the temp in is 40 and it chugs along nicely.

 

Lower is still better. We have a GSHP in an open plan barn here and the flow temp in the UFH does not need to get above 30C to keep the place warm in all but exceptional conditions.  What are the mixer valves doing? It's a terrible waste to have the heat pump make overly hot water to then have it mixed with cold. Just lower the flow temp and not have it mixed if thats an option

 

As other have said WC is an absolute must for good efficiency. Both our systems use it and keep the places at very consistent temps with no influence from internal thermostats. 

[Suffolk peasant]

15 minutes ago, Beau said:

Lower is still better. We have a GSHP in an open plan barn here and the flow temp in the UFH does not need to get above 30C to keep the place warm in all but exceptional conditions.  What are the mixer valves doing? It's a terrible waste to have the heat pump make overly hot water to then have it mixed with cold. Just lower the flow temp and not have it mixed if thats an option

 

As other have said WC is an absolute must for good efficiency. Both our systems use it and keep the places at very consistent temps with no influence from internal thermostats. 

I have opened up the the mixer to max and am going to let it settle overnight. I get daily readings so I would like to see what difference that makes - then I will lower the water if the house stays warm - but it's good to know that you keep a barn warm on 30C - I shall set it as a target to meet 🙂 

 

 

[Beelbeebub]

125kw of electricity consumed in a week?

 

If you had a cop. Of 3 that would be 500kwh delivered in a. Week. Or about 35kwh a day.

 

You don't mention the insulation levels, air tightness etc.

 

But a 60m2 semi, stone walls, single and secondary glazed windows etc, next door to me used an average of 50kwh a day over Christmas.

 

Is it possible your readings for generation are off, maybe the flow.meter is faulty (I believe the Samsung use a remote one)?

Also, if you have the upstairs rads off thry won't be availble for defrost so your system volume might be too low (depends on how big a vokumisee/buffer you have)

 

Edited 13 hours ago by Beelbeebub

[joth]

Do you have any room thermostats? How often are they calling for heat?

 

If you have rooms stats, as an experiment turn them all up to maximum so the ASHP is running continuously and see how hot the ground floor room temperature gets. Then dial back the flow temperature to a level where it's just maintaining the desired temperature throughout the GF. Note the outside temperature while running the experiment, and that's one data point you should set on the weather compensation curve.  Repeat when outside temperature is nicely above zero; WC curve sorted. 👍