Heat pump for KfW55 house 148 sqm

Since we are talking about an air/water heat pump here, I refer to the comment by Daniel-Sp that a stratified storage tank is not required for underfloor heating with a monovalent heat pump. Volume thus refers to the water in the heating pipes, as indicated by the manufacturers. Of course, according to the manufacturer specifications, the systems are monovalent systems. There are only monovalent and bivalent systems, i.e., systems that require only one heat source or several. Bivalent systems are, strictly speaking, nothing other than hybrid systems, because they always require a second backup heater, regardless of whether it operates with oil, gas, or electricity. I never spoke of a monoblock since this term is meaningless; even a monovalent system can consist of several blocks.

The fact that the sum of the heating loads is up to 30% above the building heating load has nothing to do with a safety margin but is a completely different calculation method. The building heating load from a thermal insulation calculation is not the basis for generator sizing, even if a heating engineer might present it that way. Moreover, KfW calculations are not at all, because KfW has its own rules; therefore, no energy performance certificate may be issued based on these calculations either. The safety margin comes through the heating curves because every heating engineer designs them so that no one calls in winter at Christmas to report the place is not warm. However, it must also be said that ultimately only the operator/owner can really adjust the heating curve since this requires the lowest and highest outdoor temperatures over the heating period in relation to the room temperature settings.

The heating element will always draw electricity in a bivalent system because the domestic hot water must also be heated. A continuous flow water heater is no different. This is exactly where the fresh water station improves efficiency in conjunction with a stratified storage tank and the monovalent systems. What you write is political philosophy, just as heat pumps are allegedly climate-neutral and have a primary energy factor of zero.

The kW numbers are not relevant if they have been correctly determined, but the actual annual performance factor value, because this concerns efficiency and costs. Annual performance factors >3 can currently just about compete with oil. With rising electricity prices, systems with an annual performance factor >4.7 are in demand. Bivalent systems are out of the question here, and even the monovalents reach their limits. Nothing is saved here except, of course, CO².

The BEG is being adjusted here for good reason, and photovoltaic systems will be completely excluded from BEG funding starting in 2023.

I hope you're not a heating engineer :(

Edit: A ventilation system is not mandatory for KfW55.

Sorry, apart from the statement that the KFW calculation and thermal protection verification cannot be used to determine the heating load, I cannot understand any of this....

Edit: A ventilation system is not mandatory for KfW55.

I even built KfW 40 without a ventilation system in 2019.

Since we are talking about an air/water heat pump here, I refer to Daniel-Sp’s comment that no stratified storage tank is needed for underfloor heating with a monovalent heat pump. With volume, the water in the heating pipes is meant. As also stated by the manufacturers.

Yes. That’s how it is. I don’t know what you’re confusing here or think you know. Do you mean the potable water tank when you say storage? I repeat, I have a heat pump without a stratified storage tank. I have a simple hot water tank to operate the fresh water station. Beyond that, no buffer. I could have also replaced the fresh water station with a normal potable water tank.

Of course, according to manufacturer specifications, the systems are monovalent systems. There are only monovalent and bivalent systems, i.e. systems that require only one heat source or several. Strictly speaking, bivalent systems are nothing other than hybrid systems, since they always require a second backup heating, regardless of whether operated with oil, gas, or electricity.

This is about the design. I don’t know what your problem with monovalent systems always is. I am not an expert and have no market overview, but actually every heat pump has an electric heating rod as backup. And to computationally include this here in my described case means bivalent.

I never spoke of a monoblock, since this term is pointless; a monovalent system can also consist of several blocks.

No, but in #59 you compared monovalent heat pumps with split systems. Hence my question. The comparison makes no sense. It’s like me saying a hybrid drive is superior to a car with a trailer. Doesn’t make sense.

The heating rod will always consume electricity in a bivalent system, because the potable water also has to be heated. A continuous flow heater is nothing else. Exactly here is where the efficiency advantage of the fresh water station in combination with a stratified storage tank and monovalent systems comes into play.

That is simply nonsense. I think you’re somehow thinking wrongly. Why should the heating rod be necessary for hot water preparation? Hot water is also made completely normally by the heat pump even in a bivalent design. The only case where the heating rod intervenes (which by the way is integrated in the heat pump and not in the storage tank, maybe that’s your misconception) is when temperatures are so low that the heat pump alone can no longer cover the heating demand. Then the heating rod is switched on.

What you write is political philosophy, just like heat pumps are supposedly climate-neutral and have a primary energy factor of 0.

I’m speechless except for WTF??? I simply don’t know what you want to tell me or what you are referring to with that. I have not philosophized politically at all; I have merely stated facts. Completely without judgment.

I can't understand all of that

The good thing is: I feel the same and you don't have to either. I think it is (for the majority) consensus that the heat pump is too big and I am keeping my fingers crossed that you somehow come to a better solution.