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

Air Source Heat Pumps (ASHPs)

Last Post by Joshua 1 hour ago

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Joshua

(@terry)

Active Member Member

30 kWhs

Joined: 10 hours ago

Posts: 3

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?

This topic was modified 9 hours ago by Mars

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JamesPa

(@jamespa)

Famed Member Moderator

10711 kWhs

Joined: 2 years ago

Posts: 2018

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 8 hours 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)

Active Member Member

30 kWhs

Joined: 10 hours ago

Posts: 3

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)

Famed Member Moderator

10711 kWhs

Joined: 2 years ago

Posts: 2018

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)

Active Member Member

30 kWhs

Joined: 10 hours ago

Posts: 3

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 1 hour ago by Joshua

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