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

Bookstar1 Oct 2020 18:44

#505

Ötzi Ötztaler schrieb:

These are settings that satisfy 95% of customers. The house gets warm, the bathtub gets warm. And whether the heating cycles on and off or not, you usually don’t notice it at all.

What repeatedly leads to excessively high energy consumption, and especially with too many cycles, is that every compressor less than 10 years old breaks down. And that becomes really expensive for the customers. But for system builders and manufacturers, it doesn’t matter since it’s already out of the warranty period...

Alessandro2 Oct 2020 07:13

#506

I am currently using the following settings for the heating curve:

Display of a heating controller with heating curve, three setpoint values, back/OK buttons, and orange LED.

Here is the heating curve of the mixing valve:

Heating curve M1: three return flow setpoints (18/0/-15 °C) and target temperatures (30/56/39 °C).

I have not yet performed a hydraulic balancing.
The heating limit is set to 14°C (57°F) and 18°C (64°F) for the mixing valve.
Do both heating curves need to have the same values?

face262 Oct 2020 07:32

#507

Alessandro schrieb:

I haven’t done a hydraulic balancing yet.
The heating limit is 14°C (57°F) and the mixer is set to 18°C (64°F).
Do both heating curves need to have the same values?

I’m not far enough along to have thoroughly studied settings and such, but I do know this is way too high for a new build.
The usual consequence is that rooms heat up, then the energy recovery unit (ERR) closes, the heat pump cycles on and off, the room cools down, the ERR opens again, and it repeats.

I would say you should do the balancing.

halmi2 Oct 2020 07:35

#508

In my opinion, the values are at least 8 degrees too high for underfloor heating. Why was a mixing valve installed?

Daniel-Sp2 Oct 2020 07:48

#509

Alessandro schrieb:

I have set the heating curve as follows:

Here is the heating curve of the mixing valve:

I have not done a hydraulic balancing yet.
The heating limit is set to 14°C (57°F) and for the mixing valve to 18°C (64°F).
Do both heating curves need to have the same values?

It would be best to start a dedicated thread. There you should also provide a schematic of the system hydraulics. Which devices have been installed?
Apparently, not a Novelan / Alpha Innotec heat pump.

Alessandro2 Oct 2020 08:02

#510

Okay, I’ll do that. Thanks.
I don’t know why a mixing valve is installed. I have no knowledge about heating systems.

The thread is here: https://www.hausbau-forum.de/threads/einstellungen-heizkurve-broetje-blw-neo-8.36659/

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

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