Is Your House Warmer Upstairs Than Downstairs?

Air Source Heat Pumps (ASHPs)

Last Post by benson 13 minutes ago

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GrahamF

(@grahamf)

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Joined: 6 months ago

Posts: 87

Topic starter 06/11/2025 3:35 pm

We are running our heat pump with weather compensation and a room thermostat set at 20C in the hall. In the last 24 hours, the temperature has mostly been very close to 20C. It dropped to 19.7C after the overnight hot water cycle and had just a few blips as high as 20.5C.

We have a wide staircase and quite a large landing. We leave all the bedroom doors open all the time, including at night. All the bedrooms have wide open TRVs. The bedroom radiators do not have FRVs and the lockshield valves may be fully open.

We are finding that all the upstairs rooms are running at about 21.5C - i.e. 1.5C warmer than the downstairs thermostat. We all know that hot air rises, so maybe this is just a natural result of convection?

I am wondering whether the upstairs radiators may have more water flow than they need. Therefore, I am considering installing FRVs in the bedrooms as a way to gently reduce the upstairs temperature and hopefully energy consumption.

I am interested to find out whether other people's systems have a similar temperature difference between upstairs and downstairs.

Grant Aerona 290 15.5kW, Grant Smart Controller, 2 x 200l cylinders, hot water plate heat exchanger, Single zone open loop system with TRVs for bedrooms & one sunny living room, Weather compensation with set back by room thermostat based load compensation

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JamesPa

(@jamespa)

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Joined: 3 years ago

Posts: 3324

06/11/2025 3:50 pm

Posted by: @grahamf

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I am interested to find out whether other people's systems have a similar temperature difference between upstairs and downstairs

Until I turned down the lsvs upstairs, yes. No real need to buy frvs, lsvs, or trvs fitted with decorator caps to replace the heads, will do the same, albeit with slightly more fiddling, but it's a once only job. Having adjusted the bedrooms are slightly cooler than downstairs, which we prefer.

Posted by: @grahamf

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We are running our heat pump with weather compensation and a room thermostat set at 20C in the hall

Before fiddling with the upstairs rads I would turn the downstairs thermostat up to 30 and adjust the weather compensation down to get the house temp right. This should maximise both efficiency and comfort.

This post was modified 1 hour ago 4 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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Toodles

(@toodles)

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Joined: 3 years ago

Posts: 2235

06/11/2025 3:58 pm

Our arrangement of open doors etc. is very similar to yours but we have a requirement for a slightly higher temperature (22.5 deg. C) and we heat 24/7. I have employed the LSV’s to set the output from some radiators just to even out the room temperatures. On bedroom has a programmable TRV so that we may sleep in a cooler room. All the LSV’s downstairs are fully open and the Homely Mode (temperature probe) is in the living room. The maximum variation between rooms over perhaps a week or more might be 0.4 - 0.5 degrees C. so we find our comfort level to be very stable. We have one exception as we keep the bathroom LSV fully open and enjoy a slightly higher temperature and this we appreciate no end! Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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benson

(@benson)

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Joined: 2 years ago

Posts: 205

06/11/2025 4:50 pm

We have smart TRVs in the bedrooms set at 20 or 21, but can set back further if required. We are operating under the principle that if used relatively sparingly (16 radiators in total with only 4 having TRVs) it should generally be ok, and this seems to work fine for us.

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