Hello,
This is about my parents’ house. It was built in the 1960s and is very well maintained. A few years ago, my parents had additional seals installed on the double-glazed windows, and the roller shutter boxes were insulated. For the roof, my father added a layer of mineral wool, I believe with a membrane and then drywall, but I’m not completely sure about the details. The whole house has radiators; there is no underfloor heating. The house is divided into two apartments: the ground floor is rented out, and my parents live on the first floor.
My father has been pestering me for years about the heating system. At the moment, they heat with oil. I estimate the heating system is about 15 years old, maybe a bit older. It works perfectly. My father always says that eventually it will need to be replaced anyway, and he’s not sure if he should start now because he could get good subsidies. If he waits until it breaks down, he’s uncertain whether subsidies will still be available. Would you replace a heating system that’s actually working fine now? I’m skeptical about that. With the current energy crisis, he’s even more eager to act.
The second question is what type of heating to choose now or later. Heat pumps don’t work that well with radiators, right? I have read that it’s possible to retrofit ceiling heating and then cover the ceiling with drywall. Does anyone have experience with this? Gas isn’t connected to the property anyway, and I would hesitate to consider it at the moment. Pellets, well, they are getting more expensive as well. It should also be noted that the orientation is not ideal for solar thermal or photovoltaic systems, and there are large trees casting shadows on the roof. If installing a new heating system, would solar thermal or photovoltaic panels be mandatory?
Many questions, maybe someone can give an assessment.
Best regards,
Tobi
This is about my parents’ house. It was built in the 1960s and is very well maintained. A few years ago, my parents had additional seals installed on the double-glazed windows, and the roller shutter boxes were insulated. For the roof, my father added a layer of mineral wool, I believe with a membrane and then drywall, but I’m not completely sure about the details. The whole house has radiators; there is no underfloor heating. The house is divided into two apartments: the ground floor is rented out, and my parents live on the first floor.
My father has been pestering me for years about the heating system. At the moment, they heat with oil. I estimate the heating system is about 15 years old, maybe a bit older. It works perfectly. My father always says that eventually it will need to be replaced anyway, and he’s not sure if he should start now because he could get good subsidies. If he waits until it breaks down, he’s uncertain whether subsidies will still be available. Would you replace a heating system that’s actually working fine now? I’m skeptical about that. With the current energy crisis, he’s even more eager to act.
The second question is what type of heating to choose now or later. Heat pumps don’t work that well with radiators, right? I have read that it’s possible to retrofit ceiling heating and then cover the ceiling with drywall. Does anyone have experience with this? Gas isn’t connected to the property anyway, and I would hesitate to consider it at the moment. Pellets, well, they are getting more expensive as well. It should also be noted that the orientation is not ideal for solar thermal or photovoltaic systems, and there are large trees casting shadows on the roof. If installing a new heating system, would solar thermal or photovoltaic panels be mandatory?
Many questions, maybe someone can give an assessment.
Best regards,
Tobi
D
Deliverer23 Jul 2022 12:15So: Up to a 55°C (131°F) supply temperature, using a modern heat pump is NOT a cost trap. At this temperature, the heat pump only loses about 13% efficiency compared to a 35°C (95°F) supply temperature (study from last year).
And if this has already been done:
If desired, you can also replace the radiators, which can reduce the temperature by another 6-8 degrees.
And if this has already been done:
mayglow schrieb:At most, the top floor ceiling or the roof might still be missing insulation. Then just install a suitable heat pump and you’re all set.
Facade insulated and clad, double-glazed windows ... , basement was at some point waterproofed and insulated, etc.
If desired, you can also replace the radiators, which can reduce the temperature by another 6-8 degrees.
W
WilderSueden23 Jul 2022 12:20Deliverer schrieb:
So: Up to a 55° supply water temperature, using a modern heat pump is NOT a cost trap. The heat pump only loses about 13% efficiency compared to a 35° supply water temperature (study from last year).I actually have data sheets in mind that show a bit more than 13%, even at rather mild temperatures. This combined with a high heating demand...CC35BS38 schrieb:
Try testing in winter how low the supply temperature can go. Turn the radiators fully on. You should aim for around 40°C (104°F). At 50°C (122°F) and above, it becomes quite expensive and inefficient. With a "fever temperature," you definitely cannot heat a 1960s house (without insulation measures) with radiators.
Deliverer schrieb:
So: Up to 55°C (131°F) supply temperature, using modern heat pumps is NOT a cost trap. The heat pump only loses about 13% efficiency compared to a 35°C (95°F) supply temperature (study from last year). That’s the theory, or rather in the lab. Seasonal performance factor instead of 5 just barely over 4? 🙄
50°C (122°F) would be like producing hot water all year round.
The annual performance factor would probably hover around 3 then.
(I’ve already seen that with our ground source heat pump, even though it’s from 2009, that anything above 45°C (113°F) significantly reduces efficiency.)
It would be nice if it were different, but I don’t believe in quantum leaps in heat pump technology.
Ground source heat pumps would then basically be completely unnecessary.
D
Deliverer23 Jul 2022 13:06You’ll need to find the study from ifeu yourself—I’m unfortunately not allowed to share links.
(And I have to correct myself: it was 14% more electricity between 35 and 55°C (95 and 131°F).)
Please don’t misunderstand me (or the study): I’m not recommending 55°C (131°F). But keeping this information in mind, you don’t have to worry so much if you occasionally need a flow temperature of 45°C (113°F). And with 45°C (113°F), you can already heat a lot of houses!
And if no work has been done on the house for 30 years, it’s not fair to blame the heat pump. It’s time for renovation anyway.
(And I have to correct myself: it was 14% more electricity between 35 and 55°C (95 and 131°F).)
Please don’t misunderstand me (or the study): I’m not recommending 55°C (131°F). But keeping this information in mind, you don’t have to worry so much if you occasionally need a flow temperature of 45°C (113°F). And with 45°C (113°F), you can already heat a lot of houses!
And if no work has been done on the house for 30 years, it’s not fair to blame the heat pump. It’s time for renovation anyway.
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