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
tomtom791 Oct 2020 16:08
Bookstar schrieb:

I now believe that the Novelan heat pump
It feels like almost every heat pump has this valve
Ötzi Ötztaler
1 Oct 2020 16:09
halmi schrieb:

Suddenly he starts fiddling with the settings and just wanted to raise the domestic hot water temperature, heating curve, and heating limit.
These are settings that satisfy 95% of customers. The house gets warm, the bathtub gets warm. And whether the heating cycles on and off shouldn’t normally be noticeable at all.
D
Deliverer
1 Oct 2020 16:11
pagoni2020 schrieb:

The issue mentioned here would likely occur just as well with a gas heating system, and the cause should be sought in the underfloor heating system rather than in a heat pump or gas heater. Or am I wrong?

A properly designed underfloor heating system combined with a reasonably insulated house operates with such low supply temperatures that, when there is external heat input, the floor physically cannot release any more energy—resulting in a self-regulating effect.

Neither a fireplace nor a radiator can achieve this.

Therefore, room temperature can actually be controlled better with underfloor heating than with any other system. In theory, it even allows the energy from a fireplace or the sun to be fed back into the circulation system and thus distributed to other rooms. Whether this reflects in the energy bill in the end... no idea.
T
T_im_Norden
1 Oct 2020 16:19
Alessandro schrieb:

I have now experimented with the heating curve so that the temperature is 22.5°C (72.5°F) in my home. All thermostats/valves are fully open. However, I’m not sure if the settings are correct.
My heat pump is also short cycling a lot.

Then something is not right.
Did you just turn everything all the way up and leave it at that?
A heat pump will short cycle if it cannot transfer the heat properly, so I assume your heating curve is not set correctly or something is restricting the flow somewhere.
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T_im_Norden
1 Oct 2020 16:24
pagoni2020 schrieb:

The problem mentioned here could also occur with a gas heating system, and the cause is more likely to be related to the underfloor heating rather than the heat pump or gas heater.
Or am I mistaken?

You are mistaken. A properly adjusted underfloor heating system can (almost) never overheat a room.
If the rooms are too warm, it is due to incorrect settings or solar heat gain.
If the underfloor heating only provides 22°C (72°F), it cannot heat up to 26°C (79°F).
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pagoni2020
1 Oct 2020 16:30
Okay, both answers make sense to me; I also assume a very casual approach and interpretation here, which unfortunately I have no influence over. It should be different in my own new build. In each bathroom, a towel radiator was connected to the system, and we could turn the wheel for hours without any effect. By now, I understand why, based on what I’ve read here. This was probably a quick fix by the previous owner, which is a shame considering the beautiful property.