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
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chewbacca123
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
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Bookstar
10 Jan 2021 12:20
Deliverer schrieb:

How do these values come about? Or are we talking about liters per hour? With me, the pump usually decides that 35 l/min (9.2 gallons per minute) is enough. Below 26 l/min (6.9 gallons per minute), it complains because the defrosting doesn’t proceed quickly enough. I find it hard to imagine how you could get fifty times that through the pipes...

I meant l/h (liters per hour). But your values are very high.
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Daniel-Sp
10 Jan 2021 12:30
It also depends on the size of the house.
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Deliverer
10 Jan 2021 15:19
Old building with 260 sqm (2800 sq ft) underfloor heating, temperature difference of 5°C (9°F).
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AllThumbs
10 Jan 2021 17:39
I came across this thread by chance. If I understand correctly, poor hydraulic balancing causes two problems:
  • inefficient operation and therefore higher energy consumption
  • shorter equipment lifespan due to increased compressor starts
Does point 2 also apply to modulating heat pumps?
We are getting a Nibe F2120-8, which, according to my research, is supposed to be modulating. Is there a technical term I should look for to find out the minimum output capacity?

These questions are still theoretical at this point, as we are moving in next year.
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Daniel-Sp
10 Jan 2021 20:16
Modulating heat pumps can also be cycled. You can usually find the modulation range in the technical datasheet. Try searching for it online.
tomtom7910 Jan 2021 21:39
It’s crazy that heat pumps are sold to people as a cure for CO2 emissions, but they are left alone when it comes to settings and high energy consumption. No problem though—after 10 years, they can buy a new one or pay a lot of money to replace the compressor.