Heat pump or gas with central ventilation system with heat recovery

I would never take a combination device without necessity. Here the seller benefits, not the buyer. Separate technology is more efficient, less complex, and importantly: at some point easier and cheaper to replace than some special device.

With [Kontrollierte-Wohnraumlüftung] the supply temperature can be lowered and the heat pump becomes somewhat more efficient.

Personally, in new buildings I would do:
- Heat pump + [Kontrollierte-Wohnraumlüftung]
or
- Gas + [Kontrollierte-Wohnraumlüftung] instead of solar thermal

A heat pump is the "better" technology in new buildings, but requires good planning to outperform gas at today's costs and not become a cost risk.

You don't need to overdo it with insulation, but it should be somewhat better than the energy saving ordinance and is not expensive in the right places. The pure insulation value (H't) of the envelope counts.

Photovoltaics almost always pay off regardless of the heating system, but especially of course with a heat pump.

Exaggeratedly speaking, you can hammer on gas heaters and they will keep running.

Heat pumps, on the other hand, are very sensitive to everything. Even a slightly incorrect setting or too low outside temperatures can cause a failure or significantly increased energy consumption.

A controlled residential ventilation unit as a standalone device performs the task better simply because it is only built for this purpose than a combination device.

That is the impression I have overall as well. However, I was brought back to the air heat pump because an architect said that if I take a [ZKWL] with heat recovery, then an air heat pump makes much more sense and significantly increases efficiency. Is there any truth to that?

If you take gas, then try to achieve the Energy Saving Ordinance without solar thermal, but with controlled residential ventilation + heat recovery.

How many people are you / do you plan to be? Consider this when sizing the water storage, unless you use gas.

If I could have chosen, it would have been the brine heat pump from Nibe and a controlled residential ventilation from Zehnder. These systems are regularly praised here and also in the pink forum. Of course, that does not mean the stuff from Stiebel is bad.

Oh, I thought that gas automatically means solar thermal as well. What advantage do you see in doing without solar thermal?

We are planning for four people in the future. Unfortunately, I am also restricted in device selection because of a general contractor. I suspect that Vaillant will be used here.

What should I pay attention to with a controlled residential ventilation with heat recovery? I have heard something about a Swedish company Östberg. The advantage is supposed to be that the technology runs with a rotary heat exchanger, which is better (because of humidity and mold?!).

I would never take a combination device without necessity. The seller benefits here, not the buyer. Separate technology is more efficient, less complex, and importantly: at some point easier and cheaper to replace than some special device.

With controlled residential ventilation, the flow temperature can be lowered and the heat pump becomes somewhat more efficient.

Personally, I would do in new buildings:
- Heat pump + controlled residential ventilation
or
- Gas + controlled residential ventilation instead of solar thermal

A heat pump is the "better" technology in new buildings but requires good planning to surpass gas with current costs and not become a cost risk.

You don’t need to overdo insulation, but it should be somewhat better than the Energy Saving Ordinance and is not expensive in the right places. The pure insulation value (H't) of the envelope counts.

Photovoltaics almost always pay off regardless of heating, but especially of course with heat pumps.

I had not thought of the idea of a combination device in the future either. Thank you very much! Photovoltaics are critical for us as there is not always a lot of sun and the costs certainly cannot be recovered.

I have the same overall impression. However, I was brought back to the air-source heat pump because an architect said that if I choose a ZKWL with heat recovery, then an air-source heat pump makes much more sense and greatly increases efficiency. Is there any truth to that?

if you replace enormously with slightly, supply temperature a bit...

Oh, I thought that gas automatically means solar thermal as well. What advantage do you see in foregoing solar thermal?

Solar thermal does not pay off; if you can do without it, you should.

What should I pay attention to with a controlled residential ventilation system with heat recovery? I have heard of a Swedish company Östberg. The advantage is said to be that the technology uses a rotary heat exchanger, which is better (because of moisture and mold?!).

For a single-family house, you should make sure that the device is properly sized and has an enthalpy exchanger.

I had not yet considered the idea of the combined device in the future. Thank you very much! Photovoltaics are critical for us since there is not always much sun and the costs certainly cannot be recovered.

Do you live in the forest or on a north-facing slope? Then you should actually avoid it. Otherwise, photovoltaics always make sense.

I have the same overall impression. However, I was brought back to the air heat pump because an architect said that if I choose a ZKWL with heat recovery, then an air heat pump makes much more sense and greatly increases efficiency. Is there some truth to that?

No matter what you decide. The controlled residential ventilation should be considered separately. Because this basically "increases" the efficiency of every heating system (if you follow the same thought) since ventilation losses are missing as a result.

However, if controlled residential ventilation must first appear in the positive aspects for an air heat pump because it increases efficiency, then I would think it over three times. Because conversely (just thinking out loud) it means that without controlled residential ventilation an air heat pump is not efficient enough.

Oh, I thought that gas automatically means solar thermal. What advantage do you see in foregoing solar thermal?

No, not really, but it has to be calculated very precisely and there are replacement measures that make it possible, with appropriate house construction, to forgo ST and have only GAS + controlled residential ventilation.

For example, I saw no sense in that and simply took GAS + controlled residential ventilation + ST.

What should I pay attention to in a controlled residential ventilation with heat recovery? I have heard of a Swedish company Östberg. The advantage is said to be that the technology works with a rotary heat exchanger and that this is better (because of humidity and mold?!).

A rotary heat exchanger is not necessarily the best choice.

Disadvantages compared to plate heat exchangers are:

Noise
higher maintenance costs and wear
higher power consumption
possible mixing of exhaust and supply air

I would choose a conventional system with an enthalpy heat exchanger from e.g. Wolf, Helios, Zehnder, Brink or similar.

What should I pay attention to with a controlled residential ventilation system with heat recovery? I have heard something about a Swedish company called Östberg. The advantage is supposed to be that the technology runs with a rotary heat exchanger and that this is better (because of moisture and mold?!).

We have a controlled residential ventilation system from Östberg with a rotary heat exchanger. Rotation is rather unusual and has advantages and disadvantages. Moisture and mold are not among them. With controlled residential ventilation, I would take whatever the installer prefers to install; in my opinion, the manufacturer and even the heat exchanger are not as important as proper installation and planning.

What is important: moisture recovery and no undersizing.

If you use gas, then try to meet the Energy Saving Ordinance without solar thermal energy, but with controlled residential ventilation + heat recovery.

Are you sure that is possible? I spoke with an energy consultant yesterday and happened to ask exactly this point. He said that controlled residential ventilation cannot replace solar thermal energy because controlled residential ventilation does not use renewable energy (or something like that, I don’t quite remember the exact reasoning). To comply with the Energy Saving Ordinance with a gas boiler, solar thermal energy is therefore necessary despite controlled residential ventilation (with heat recovery).