solar gain in south rooms best approach?

Air Source Heat Pumps (ASHPs)

Last Post by Judith 10 months ago

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AdamK

(@adamk)

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Joined: 11 months ago

Posts: 198

Topic starter 03/03/2025 10:44 am

thinking forward to when im running on a heat pump, i have quite a big solar gain in some rooms as they are south facing and have large windows. currently not a problem as i use a gas boiler and wireless trvs in each room but with an open loop HP could cause cycling. do i put maybe the trvs to an upper limit say 2c above the normal temp the house sits at? thus just acting to stop some rooms from over heating. example one rear bedroom that has no rad on only the boiler and cylinder in a cupboard about 3mx3m got to 24c quite easily Sunday.

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JamesPa

(@jamespa)

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Posts: 3885

03/03/2025 11:12 am

Posted by: @adamk

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do i put maybe the trvs to an upper limit say 2c above the normal temp the house sits at?

Thats definitely one option.

I also have south facing rooms. One, our main living room has a fan radiator which modulates its fan down and eventually off, so that pretty much fixes that (in summer I might even use it for cooling). The others are bedrooms; at present I am grateful for the extra warmth, in summer I plan to leave the curtains closed during the day as I did last summer, simples!

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: 2419

03/03/2025 3:51 pm

@jamespa We also have SSW facing rooms that have high solar gain. We use a TRV in one and we have vertical white slat blinds in that and another room plus a white roller blind in the bathroom. Come midday or so, if solar gain is starting to be noticeable, the blinds are closed and the rooms remain very comfortable. Regards, Toodles.

This post was modified 10 months ago by Toodles

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

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Judith

(@judith)

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Joined: 2 years ago

Posts: 451

03/03/2025 5:24 pm

We have outside canopies which we roll down to reduce the (extreme) heating effect of large south facing windows and patio doors. In the kitchen this external blind reduces the temperature by 7C virtually instantly. In the evening we pull the curtains over on the west side.

The canopies must be rolled shut when it’s windy.

Our ashp has a mode which is called extended which is WC plus it switches off when above the internal temperature (and then back on again after it cools).

2kW + Growatt & 4kW +Sunnyboy PV on south-facing roof Solar thermal. 9.5kWh Givenergy battery with AC3. MVHR. Vaillant 7kW ASHP (very pleased with it) open system operating on WC

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