2-family house KFW70 heating with air heat pump ventilation and exhaust ventilation

hello

it is about a new building. 2-family house. we are interested in the ground floor apartment (with garden). it has 100m², a base slab, underfloor heating, it is a Kfw70 house, and the heating system is an air heat pump. additionally, the apartment is automatically ventilated.

now my questions.

is an air heat pump recommended as heating? most of my acquaintances say no. too expensive (electricity costs rise enormously) and it is better to install a gas heating system. also, the problem in summer with unnecessary costs for hot water preparation and the pump continues to run even when not in use.

second topic. automatic ventilation. sounds good (sales pitch): no more airing, windows can normally stay closed, etc. BUT how long does the ventilation work without faults? what happens in case of defects? if something is clogged or whatever? here they always beat around the bush. in the end, the house would have to be opened and everything repaired at great expense, right?

who has experience and possibly figures for me? I like to calculate with real costs and values and not with the numbers given in sales talks.

Good evening,

many questions at once, so there should also be a few answers.
Your text is extremely difficult to read, as not only numerous conventions regarding spaces and punctuation are violated, but also the use of capital letters in regular writing is completely neglected.
For the economic evaluation of a selected heat generator, knowledge of the realistically expected heating loads is necessary, as well as knowledge of the connection and installation costs. In addition, there are numerous legal framework conditions. Therefore, a general statement like 'Gas is cheaper' or 'Heat pumps are no good' is not helpful.
On the topic of ventilation systems, there are numerous contributions on the internet. One should distinguish between strongly ideologically influenced and technically sound positions, and then decide based on the individual project. Important here is not only the difference between 'central' or 'decentralized' system. And no one can say how long the system will operate without failure. There is only a certain probability that it will function without failure for a certain period. The necessary steps for maintenance, error correction, and replacement depend again on the chosen system.

For my project, a ventilation system is simply necessary due to the framework conditions 'when and how long ventilation can take place' – the required ventilation intervals could not be maintained otherwise. For this, an air-water heat pump as a heat generator is not the most expensive solution.

Best regards
I.

From your text, however, I cannot extract anything useful that leads to the answering of my questions.

There are systems where you can turn off the air heat pump for the underfloor heating in summer. Domestic hot water storage runs with a separate air heat pump.

Hello,

....air/heat pump recommended as heating...?

If the conditions are right and the system is well planned/dimensioned, yes.

....most of my acquaintances say no. too expensive (electricity costs are rising to an immeasurable extent)...

Where do these acquaintances get their knowledge for this general, false conclusion?

....and the pump keeps running even when not in use...

Someone probably hasn’t read the manual or misunderstood the existing control system!

Best regards.

Now the conclusion that an air heat pump does not deliver what one hopes for and that one heats with electricity is partly correct. Because most systems are not properly planned/dimensioned.

At least that’s my experience over the past few years... with all the cookie-cutter houses being built nowadays, something is installed that roughly fits and can deliver the heating loads... (on paper) but in reality, the electric heating element runs at low temperatures, and it certainly consumes quite a bit...

So, in my opinion, an air heat pump is a very expensive heating option nowadays, because, as mentioned, it is usually built according to a one-size-fits-all approach...

A geothermal or groundwater heat pump is of course a completely different matter.

On the topic of ventilation:

A central ventilation system is practically mandatory today in highly insulated and airtight houses... anyone who still hasn’t understood this is beyond help... because hardly anyone can maintain the ventilation intervals, and when building damage occurs, the builder is off the hook, since it very often says "ventilation intervals not maintained."

Now the moisture must be removed, and assuming one is employed—which I think is the case if one builds a house—then one simply cannot ventilate 3-4 times a day because one is not there...

I have not regretted my decision and had a central controlled residential ventilation system installed during the construction 2 years ago... the extra 5-6 thousand euros everyone should be able to afford, that’s peanuts compared to the construction costs, but people often save here and rather install some optical gimmick like better tiles or sanitary fixtures...

My system has been running flawlessly for 2 years... but it’s like with a car... maintenance is necessary... so filter changes about every 6 months (price-wise negligible since from the roll about 10€/sqm ~1€ per filter)... just vacuum the valves and every 10 years a cleaning of the ducts should be carried out... of course, there are specialist companies for this, nothing has to be opened up etc., only the valves are unscrewed and through them one has access to the pipes... one should have access to the ventilation unit itself anyway.

If the system is properly installed, there is no need to tear open ceilings or walls afterwards... if something breaks, it is at the ventilation unit itself... and this is like all electronic devices... you can also get unlucky and it breaks after 2 days... but since the technology is relatively simple, every ventilation technician is able to procure and install spare parts.

A clogging of the ventilation ducts is practically excluded, as the pipes are sufficiently dimensioned and filters or grids should be present everywhere at the inlets and outlets... of course, if someone deliberately stuffs something in, then that can also happen.