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Samsung Gen 7 R290 12kW is not behaving how I expected

 
Air Source Heat Pumps (ASHPs)
Last Post by Broadsman 12 months ago
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 Joshua
(@terry)
Eminent Member Member
Joined: 12 months ago
Posts: 10
Topic starter 09/03/2025 1:34 pm  

Hello

Long term lurker who, after reading various posts on here and having a pleasant temperature winter, thought that they'd set their heat pump ok, but now we're warning up is very much doubting they have

I have a Samsung Gen 7 R290 12KW. It's been working ok through the winter (a pretty constant 21c in the house) so I thought I had weather compensation set up ok but we've just warmed up here in the UK and my house is now unbearably warm. Looking at the settings and outputs I'm confused as to why it's doing what its doing, so wondering if I actually have it set up the way I thought I had

So settng wise I thought I had a weather curve set up from -2/+15 with flow temps 40/25c accordingly. The heat pump set to turn heating off at 16c. Photos attached

But looking at it today the heat pump is saying it is 15.6 outside yet is pumping 34c water around the rads and ufh and the house is 24c inside.

I'm now wondering if I don't we l really have it running in weather compensation and I've just been lucky that the house has sat at constant 21 through the last couple of months of cold weather.

Can anyone help please?

PXL 20250309 124123735
PXL 20250309 111404408
PXL 20250309 110913603
PXL 20250309 110925393
PXL 20250309 110859917

This topic was modified 12 months ago by Mars

   
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JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 4292
09/03/2025 2:31 pm  

The first picture shows its operating according to water law but Im confused about the screenshot which seems to show water law for Zone 1 and then for Zone 2.  Are you sure you havent programmed one end of the curve in Zone 1 and the other end in Zone 2!  It might be worth checking FSV 1032 as well although I dont think this should be a problem.

Is it operating constantly at 34C or was that a spot measurement, it could be cycling on and off peaking at 34.

 

I dont have a samsung; someone who does may be able to be more precise


This post was modified 12 months ago 2 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 Joshua
(@terry)
Eminent Member Member
Joined: 12 months ago
Posts: 10
Topic starter 09/03/2025 5:39 pm  

Thanks

 

Looking further on this site in thinking I'm suffering from this

 

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/samsung-weather-compensation-oddities

 

 



   
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JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 4292
09/03/2025 8:58 pm  

"had a bit more success today and got the flow down to 32degrees and got closer to balance, but ultimately the temp kept increasing and would not stop even as I reduced the temp on the controller."

happens because the system is oversized and/or its mild outside.  Cycling occurs because the heat pump cant turn down sufficiently to match the demand from the house.  This manifests itself as the flow temperature rising above the set point until it reaches a threshold at which the heat pump decides to switch off for a while.  Thus the heat pump switches on and off so that the average output (over time) matches the demand.  All heat pumps (and boilers) do this.  A 'right sized' heat pump will likely do it at an OAT of 10-12 or thereabouts.  An oversized heat pump may do it down to the point at which cycling due to defrost kicks in!  Cycling does cause an efficiency penalty, but it is currently unquantified (and possibly exaggerated for historical reasons).

Thats why I asked "Is it operating constantly at 34C or was that a spot measurement, it could be cycling on and off peaking at 34."


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 Joshua
(@terry)
Eminent Member Member
Joined: 12 months ago
Posts: 10
Topic starter 09/03/2025 9:15 pm  

Looking at it since it's been a steady 34

The heat pump is definitely oversized. We could have done with 9k but they came in 8 or 12.

So if I've parsed that other thread correctly. 

I need to set my lowest warm weather flow to the lowest my system can manage, namely 34. Then use my thermostats to turn it off during these mild periods.

 

Or I can change the 2093 so it cycles and keep my flow temperature lower?


This post was modified 12 months ago by Joshua

   
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 Old_Scientist
(@old_scientist)
Prominent Member Member
Joined: 2 years ago
Posts: 346
09/03/2025 10:51 pm  

Yes, that sounds correct.

I would say try both options and see which works best for you. I wouldn't aim too low though, if you already know 34C is required to dissipate the heat produced - maybe try 30C to start and see how often it's cycling (you really don't want it short cycling multiple times per hour).

I prefer to let my room thermostat control the on/off cycles, but that's just my personal preference. In milder weather the system may be on for an hour then off for 1-2 hours depending on OAT.

 


This post was modified 12 months ago by Mars

Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.


   
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 Joshua
(@terry)
Eminent Member Member
Joined: 12 months ago
Posts: 10
Topic starter 10/03/2025 9:43 am  

So I turned my thermostats down last night 

 

And when I woke up this morning, although the bedroom was 22, the flow temp in the boiler was only 12.5, so it had clearly been off for a while, and I could see the thermostat controls were unlit, showing they weren't asking for heat. 

 

I just went back a moment ago though and despite the thermostats not asking for heat, the flow temp is back up to 42. The pumps aren't on and the radiators are cold though so the house isn't heating up. Does this sound right? 

 

I'll give the manual a good read this evening and try and figure out those 2091, 2092 and 2093 settings


This post was modified 12 months ago by Joshua

   
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JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 4292
10/03/2025 3:10 pm  

Posted by: @terry
↑

I need to set my lowest warm weather flow to the lowest my system can manage, namely 34. Then use my thermostats to turn it off during these mild periods.

 

Or I can change the 2093 so it cycles and keep my flow temperature lower?

Definitely its in the 20xx FSVs.

Conversely it may be that you need to reduce 2022/2032 further as well as changing 2093 so it operates on pure WC.  I don't know if Samsung calculates the energy integral (the difference between target flow temperature and actual flow temperature integrated over time).  If it does then it could/may/will use this to adjust the cycles so that on average they deliver the same amount of energy as would have been delivered at the target flow temperature, which it can do by inserting an I component into the control loop.  I know Vaillant heat pumps use the integral for some purposes, I have yet to find out if mine uses it for this purpose.


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 Broadsman
(@broadsman)
Estimable Member Member
Joined: 2 years ago
Posts: 73
11/03/2025 9:50 am  

I have the same pump and if I am operating it correctly you need to touch/hold/release the blue bar on the bottom left of the controller which says "heat". It should then change to give you three options, one of which is Auto. Select Auto and you are then on Water Law. Hope this works for you.



   
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