ᐅ Underfloor heating with an air-to-water heat pump. House gets too warm when the sun is shining.

Created on: 4 Dec 2019 14:18

Hello everyone,

I have a general question.

We moved into our new build four months ago. The living area on the ground floor has three large floor-to-ceiling windows facing south. We have underfloor heating and an air-to-water heat pump.
It provides a really comfortable temperature inside the house, but we have a problem – whenever the sun is shining in winter, even if it’s -2°C (28°F) outside, the temperature suddenly rises to 24°C (75°F) in the living room. It gets uncomfortably warm in here, and the underfloor heating can’t be turned down quickly.
Should we assume that the large floor-to-ceiling windows are responsible for the heat gain? A photo of the south-facing side of the house is attached.
What would you do – always lower all the blinds as soon as sunlight is forecast? That seems quite annoying...
We have motorized blinds controlled by Somfy. Would you consider buying a sensor that automatically lowers the blinds at a certain temperature?

Thanks in advance for your replies.

Neues zweistöckiges Haus auf Baustelle mit weißer Blockfassade, pinker Dämmung und großen Fenstern

Stefan89026 Dec 2019 21:57

#295

A quick question related to the topic:
Is there any reason not to keep the towel radiator (hydronic) in the bathroom (connected to the same heating circuit as the underfloor heating) running continuously (for additional support)?

Daniel-Sp26 Dec 2019 22:22

#296

First of all, there is hardly any heating output at the typically low supply temperatures of underfloor heating. How long do you expect to hang a towel to dry at a supply temperature of about 28°C (82°F) or lower?
Secondly, you need to significantly reduce the flow rate to avoid a thermal short circuit. This further decreases the heating output.
Therefore, it is better to install an electric towel radiator without affecting the underfloor heating. This works better for occasional additional heating.

Musketier26 Dec 2019 22:22

#297

Stefan890 schrieb:

A quick question related to the topic:
Is there any reason not to keep the towel radiator (hot water) in the bathroom running continuously (it’s on the same heating circuit as the underfloor heating) as additional support?

I did that in my home because the bathroom was/is also my "problem area." A larger heating surface means a lower flow temperature is needed.
I also did this in the guest bathroom, where it works great for drying wet kids’ clothes.

tomtom7926 Dec 2019 23:15

#298

Does it make sense at 28°C (82°F) supply temperature?

It’s better to decouple the towel radiator and heat it with an electric heating element.

Musketier26 Dec 2019 23:59

#299

It definitely helps to some extent. A towel radiator has a relatively large surface area after all. Ultimately, the floor doesn’t get any warmer and heats the entire room. A heating cartridge would probably be more effective, but unfortunately, I don’t have an electrical outlet nearby. So I’m making the best of it.

tomtom7927 Dec 2019 00:10

#300

It’s true, increasing the heating surface is an advantage.

I miss my old towel radiator that was 40-50°C (104-122°F).

ᐅ Underfloor heating with an air-to-water heat pump. House gets too warm when the sun is shining.

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