with / without central ventilation system experiences

And if the operating costs vs heater savings even out, what about the maintenance costs? Do you have to buy new filters frequently or is it enough to clean the existing filters regularly?

Maintenance costs are not representative for us, since we have the entire unit serviced (air-to-water heat pump + ventilation). That amounts to about €450 every 2 years and also includes the replacement of the ventilation filters in our combined unit. Although you can also replace them yourself, and replacing them more often than every 2 years certainly wouldn't hurt, especially for allergy sufferers.

We clean and/or replace the cone filters behind the exhaust air approximately every 3 months. You can wash them a few times under hot water with a strong water jet. But eventually, they start to look like they have been washed already. When they no longer look good, I replace them with new ones. A pack of 20 replacement filters costs around €20 and should last us 2-3 years.

Out of interest:

How is the humidity in winter with the controlled residential ventilation system at your place? What values do you have on average?

My brother-in-law (timber frame house with EPS insulation, foil, controlled residential ventilation without enthalpy exchanger) said the other day that he currently has 20-25% humidity and – no joke – he is getting cracked to slightly bloody hands. He is also currently working from home all the time. :oops:
Is that possible?

We are also completely working from home, so always at home during the week. I have absolutely no problems with humidity. I’m not measuring it now, but I don’t feel that it’s either too humid or too dry here. We have this promotional weather station lying around, which shows 33% at Humidity. But whether that thing is any good (or 33% would be okay) I really can’t tell you.

My brother-in-law (timber frame house with EPS insulation, foil, controlled residential ventilation without enthalpy exchanger) said the other day that he currently has 20-25% humidity and

Currently 35% (albeit with decentralized controlled residential ventilation), somewhat less during the day with strong sunlight.

33% is, if correct, not good or too dry. You don’t immediately get bloody [Inhalte in eckigen Klammern dürfen nicht übersetzt werden], but the respiratory tract is certainly somewhat more stressed. 40-50% is optimal, whereas 60% already represents the limit towards too moist. However, this is more of a construction issue and indirectly affects the organism negatively. The body would initially feel comfortable even at 70-80%, until the first mold spores appear.

We have also set values on the system from 50-60%. So 60 as maximum and 50 as minimum. But I think we have turned off the program that takes care of that. So the current value is apparently the "default". However, I will not mess with it now since we feel comfortable and I rather assume that the measurement from our "Werbegeschenk" is not correct. ;)