ᐅ Fresh Air Heating vs. Air-to-Water Heat Pump Installed Indoors – Alternatives?
Created on: 21 Mar 2022 12:31
F
Flitzer
Hello everyone,
We are currently planning a new house. Unfortunately, according to the local development plan, the outdoor installation of an air-to-water heat pump is not allowed. Personally, I find an indoor installation unappealing at the moment (space in the technical room, large holes in the wall, noise(?)), but I’m open to being convinced otherwise.
We have now received initial offers for a fresh air heating system (air-to-air heat pump), which I find quite attractive due to the filtering and cooling functions, allowing us to sleep with closed windows in summer (highway within sight, no speed limit, <<1km (0.6 miles)).
Unfortunately, I have not found much positive information online about such a fresh air heating system (and only few well-founded negatives…). At least not when the outdoor installation of an air-to-water heat pump with underfloor heating is off the table. Also, so far no provider has addressed my inquiry regarding a horizontal ground collector (because it’s expensive).
Fossil fuels are out of the question, electricity would come from the solar panels on the roof (possibly with storage).
1) Has anyone had good experience with a fresh air heating system (ceiling diffusers)? --> Bathroom planned with infrared ceiling panels
2) What would be a reasonable alternative?
3) Is an integrated installation of an air-to-water heat pump really as unattractive as the house builders suggest? --> They tend to tell you only what benefits them, and in the prefab house sector, "ventilation is the best invention since beer," as they say ;-)
By the way, KFW-55 standard, optionally KFW-40, no basement, about 150m² (1,615 sq ft) living area with a pitched roof. Funding is secondary for now.
Thanks
Flitzer
We are currently planning a new house. Unfortunately, according to the local development plan, the outdoor installation of an air-to-water heat pump is not allowed. Personally, I find an indoor installation unappealing at the moment (space in the technical room, large holes in the wall, noise(?)), but I’m open to being convinced otherwise.
We have now received initial offers for a fresh air heating system (air-to-air heat pump), which I find quite attractive due to the filtering and cooling functions, allowing us to sleep with closed windows in summer (highway within sight, no speed limit, <<1km (0.6 miles)).
Unfortunately, I have not found much positive information online about such a fresh air heating system (and only few well-founded negatives…). At least not when the outdoor installation of an air-to-water heat pump with underfloor heating is off the table. Also, so far no provider has addressed my inquiry regarding a horizontal ground collector (because it’s expensive).
Fossil fuels are out of the question, electricity would come from the solar panels on the roof (possibly with storage).
1) Has anyone had good experience with a fresh air heating system (ceiling diffusers)? --> Bathroom planned with infrared ceiling panels
2) What would be a reasonable alternative?
3) Is an integrated installation of an air-to-water heat pump really as unattractive as the house builders suggest? --> They tend to tell you only what benefits them, and in the prefab house sector, "ventilation is the best invention since beer," as they say ;-)
By the way, KFW-55 standard, optionally KFW-40, no basement, about 150m² (1,615 sq ft) living area with a pitched roof. Funding is secondary for now.
Thanks
Flitzer
B
Benutzer20021 Mar 2022 15:21Flitzer schrieb:
Why is ventilation a no-go for a KFW55 house? Is the insulation not sufficient? Because the air-to-air heat pump extracts its heat from the exhaust air to provide heating. With the heating demand of a KFW55 house, you will consume a lot of electricity in winter—almost like using a hairdryer. The electricity is converted 1:1 into heat. A standard heat pump achieves up to 5:1 (1 unit of electricity produces 5 units of heat). That’s why this type of heating is not suitable for poorly insulated buildings.
Flitzer schrieb:
What realistic drawbacks are there besides electricity consumption for an air-to-air heat pump with heat recovery? None. Except that you might end up paying about €2,000 (around $2,200) in heating costs for a new build (and you won’t get the warm floor sensation you have with underfloor heating). You’d also need to add a ground heat exchanger and a heat pump for domestic hot water.
Flitzer schrieb:
If I already have a solar system on the roof, then it’s okay if the heating uses electricity. Unfortunately, you have to heat during winter when the sun isn’t shining.
Flitzer schrieb:
And it’s not even that cheap if you have to rent an excavator. Is €200 (about $220) for a whole weekend too expensive for you?
Flitzer schrieb:
The heat pump in the attic would be an option I only considered briefly… but there’s still that noisy unit in the house above the bedrooms… It’s not noisy. It’s just a large fan moving a lot of air, so it produces wind noise.
Alright, several sensible arguments have come up here that I hadn’t found online before... I honestly didn’t expect such high electricity consumption and poor efficiency, especially since everything was so nicely explained during the appointment with the claim that it would be fantastic and that everyone who installs it would save a lot :-(
A lesson learned, and fortunately, this time in time. Looks like the ventilation topic is dead for now. A pity, really.
200€ (about $215) for the excavator wouldn’t actually be a problem; it’s more that I can’t operate one ;-) and don’t know anyone who can. But I think I’m going to put the suppliers under pressure to make them think about it (I believe they’re unfamiliar with this, so they don’t want to do it) — the heating installer has to cooperate as well.
Thank you very much.
Can I close the thread, or will someone else do it?
A lesson learned, and fortunately, this time in time. Looks like the ventilation topic is dead for now. A pity, really.
200€ (about $215) for the excavator wouldn’t actually be a problem; it’s more that I can’t operate one ;-) and don’t know anyone who can. But I think I’m going to put the suppliers under pressure to make them think about it (I believe they’re unfamiliar with this, so they don’t want to do it) — the heating installer has to cooperate as well.
Thank you very much.
Can I close the thread, or will someone else do it?
B
Benutzer20021 Mar 2022 15:38Flitzer schrieb:
It seems the topic of ventilation has just died. That's a pity, really.Why? I would still always install a ventilation system. However, this has nothing to do with the heating system but with airtight buildings.
An air-to-air heat pump is a type of heat pump, similar to an air-to-water heat pump, but the recovered heat energy is released into the air rather than into water. However, on the market, I am only aware of one system for an exhaust-air air-to-air heat pump. This system has only a limited heating capacity, and its efficiency is not very high, with a coefficient of performance (COP) of just under 2. Claims of a 1:1 efficiency ratio are completely incorrect.
I always find it surprising who confidently presents themselves as an expert here. I am a certified energy engineer (Dipl. Ing.) and provide consultations on the side as a kind of hobby. I am absolutely independent of manufacturers and types.
Exhaust air systems, i.e., exhaust-air heat pumps, are very appealing because the house does not lose heat through ventilation. There are two good systems on the market, both of which are air-to-water heat pumps and can achieve a seasonal performance factor (SPF) of 3 to 4 when properly designed (e.g., Vaillant versoTherm and Nibe F750). The weak point of these exhaust air heat pumps is also the limited heating capacity of realistically about 5–6 kW (thermal). Both systems are efficient without an electric heating element down to about -15°C (5°F) outdoor temperature.
For a 150 m² (1,615 sq ft) house built to KfW 55 standard, the heating capacity will likely be tight. In your case, I would recommend around 8 kW heating capacity, inverter-controlled.
With proper sizing, the heat pump runs 24 hours a day during winter, but at low power levels. This is how the heat pump achieves its efficiency.
An indoor installation is inaudible if the heat pump is installed with insulation. The humming noise should not be underestimated. However, with insulated installation plus soundproof doors, the heat pump sounds no louder than a refrigerator in the living area at most.
Personally, I am not a fan of air-to-air heat pumps because the comfort of a warm floor is very different from a warm airflow. In addition, air is a poor heat carrier. For the air-to-air heat pump to operate efficiently, it must push a lot of air at a low heating temperature (~26–30°C (79–86°F)) into the living space, which risks drafts. Furthermore, a underfloor heating system can also serve as a heat storage.
I always find it surprising who confidently presents themselves as an expert here. I am a certified energy engineer (Dipl. Ing.) and provide consultations on the side as a kind of hobby. I am absolutely independent of manufacturers and types.
Exhaust air systems, i.e., exhaust-air heat pumps, are very appealing because the house does not lose heat through ventilation. There are two good systems on the market, both of which are air-to-water heat pumps and can achieve a seasonal performance factor (SPF) of 3 to 4 when properly designed (e.g., Vaillant versoTherm and Nibe F750). The weak point of these exhaust air heat pumps is also the limited heating capacity of realistically about 5–6 kW (thermal). Both systems are efficient without an electric heating element down to about -15°C (5°F) outdoor temperature.
For a 150 m² (1,615 sq ft) house built to KfW 55 standard, the heating capacity will likely be tight. In your case, I would recommend around 8 kW heating capacity, inverter-controlled.
With proper sizing, the heat pump runs 24 hours a day during winter, but at low power levels. This is how the heat pump achieves its efficiency.
An indoor installation is inaudible if the heat pump is installed with insulation. The humming noise should not be underestimated. However, with insulated installation plus soundproof doors, the heat pump sounds no louder than a refrigerator in the living area at most.
Personally, I am not a fan of air-to-air heat pumps because the comfort of a warm floor is very different from a warm airflow. In addition, air is a poor heat carrier. For the air-to-air heat pump to operate efficiently, it must push a lot of air at a low heating temperature (~26–30°C (79–86°F)) into the living space, which risks drafts. Furthermore, a underfloor heating system can also serve as a heat storage.
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