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
C
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.
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.
Ötzi Ötztaler9 Oct 2020 17:58
Daniel-Sp schrieb:
Quite simple, without scripts...Your suggestion would work, but it would almost always lead to the heating curve shutting off near the end of the day, because the current return temperature will usually be above the hysteresis band around the now lowered setpoint. Then there will be a heating pause for several hours in the late afternoon until the return temperature has dropped by twice the hysteresis value. After that, the system will switch back on at full power in the cold night. I’m not sure how much more efficient this would actually be, especially since I get cheaper off-peak electricity at night and pay the full price during the day due to the lack of photovoltaics. Using scripts would allow for more flexible control.Admittedly, the playful challenge is more the motivation here than the estimated savings of about 3 euros per heating month, which would probably require a lot of optimization effort to achieve...
So here is a progress update:
From early October until now: 140 kWh consumption
The heat meter shows 578 kWh
This results in a COP of 4.1
What can I say, we have 22.5°C (72.5°F) everywhere, the system is running without any issues and has become extremely efficient. I’m really very satisfied and also glad that the system is finally working satisfactorily.
Now I’m curious to see how much the COP will drop when we consistently have temperatures below 0°C (32°F).
From early October until now: 140 kWh consumption
The heat meter shows 578 kWh
This results in a COP of 4.1
What can I say, we have 22.5°C (72.5°F) everywhere, the system is running without any issues and has become extremely efficient. I’m really very satisfied and also glad that the system is finally working satisfactorily.
Now I’m curious to see how much the COP will drop when we consistently have temperatures below 0°C (32°F).
I still haven’t turned on the underfloor heating. The fireplace runs 16-18 hours when there is no sun. When the sun is shining, the house heats up by itself through the window areas.
I’m curious how long we’ll keep going like this.
Currently, the temperature is 23.7°C (74.7°F) on the ground floor, 20°C (68°F) in the basement, and 20.5°C (68.9°F) on the upper floor.
I’m curious how long we’ll keep going like this.
Currently, the temperature is 23.7°C (74.7°F) on the ground floor, 20°C (68°F) in the basement, and 20.5°C (68.9°F) on the upper floor.
Does the fireplace heat the entire house? We can only use it to heat the living area on the ground floor; unfortunately, no heat reaches the upper floor. That’s why the underfloor heating has to be running; otherwise, it would be really cold upstairs. We also only heat with wood every few days.
Our windows are rather small, which I think makes a big difference. I see this with the neighbors—they still keep their blinds down during the day, probably because otherwise it gets too warm...
Our windows are rather small, which I think makes a big difference. I see this with the neighbors—they still keep their blinds down during the day, probably because otherwise it gets too warm...
Bookstar schrieb:
Does the fireplace heat the entire house? We can only use it to heat the living area on the ground floor; unfortunately, no heat reaches the upper floor. That’s why the underfloor heating has to be running, otherwise you would really be cold upstairs. We also only burn wood every few days.
Our windows are rather small, which I think makes a big difference. I see it with the neighbors—they still keep their blinds down during the day, probably because otherwise it gets too warm... At least the fireplace is currently the only heat source in the house. I suspect it does help somewhat because of the open staircase leading to the basement and upper floor, and also due to the chimney running through the upper floor.
What I do notice is that an airtight (room air-independent) fireplace is far less effective than a room air-dependent one. I once attended a seminar in a farmhouse where an old wood stove stood in the middle; after one hour, it was unbearable in there. At home, the temperature never goes above 24 degrees Celsius (75°F) on the ground floor when using the fireplace.
We have a lot of window area on the ground floor. The difference between sunny and cloudy days is really significant.
Hardwood is not cheap either, but if it allows me to avoid using the air-to-water heat pump for a total of two months during autumn, winter, and spring, then it’s worth it.
Personally, I find 20 degrees Celsius (68°F) in the bedrooms unusual, but it’s supposed to be the optimal sleeping temperature, for whatever reason.
Zaba12 schrieb:
At least the fireplace is currently the only heat source in the house. Because of the open stairwell leading to the basement and upper floor, I assume it makes some difference, also because of the chimney that runs through the upper floor.
What I notice, however, is that an open-flue fireplace is far less efficient than a closed combustion fireplace. I once attended a seminar in a farmhouse where an old stove stood in the middle of the room; after one hour it was unbearable in there. At home, the temperature with the fireplace on the ground floor never goes above 24 degrees Celsius (75°F).
We really have a lot of window area on the ground floor. The difference between sunny and cloudy weather is quite significant.
Hardwood is not free either, but if I can manage to avoid using the air-to-water heat pump for two months in total during autumn, winter, and spring, then it’s worth it.
I personally find 20 degrees Celsius (68°F) in the bedrooms unusual, but that is supposed to be an optimal sleeping temperature, for whatever reason.I simply doubt whether you can really save with the wood. That depends heavily on the individual prices and efficiency.@Bookstar COP including hot water? And do you find heat pumps great after all?
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