Controlled residential ventilation yes - heat recovery no - justification in the text!

- Regular filter cleaning (if I have to breathe in all that’s stuck in the filters, I get sick) you can do yourself
- new coarse filter: costs cents if you buy roll stock and cut the filter to size

Tell me - I still have an unused filter from a former range hood (not an activated carbon filter). At first glance, it looks like the coarse filters of my decentralized fans. I have been thinking for a while whether I could cut it to size accordingly and use it as a replacement at the next cleaning.
Even though you have a controlled residential ventilation system and I have a decentralized one – what do you think, would this be potentially possible (then the filter would at least still have a useful purpose, since the range hood has long since gone to the Jordan)?

What about the heat exchanger? A heat exchanger with moisture recovery must also transfer particulate organic material from the exhaust air to the supply air, right? That is already impossible for hygiene reasons. How is it with conventional heat exchangers, is any contact in the HE categorically and technically 100 percent safely excluded?

Are there no bacteria or germs worldwide that can also cope with low humidity?

But now I have it: What about in summer? Warm and still saturated air is drawn in and cooled in the HE. Air humidity 100 percent and on the way to the supply air opening, the 25-35 degree warm air cools further towards the temperature of the building structure. Continuous condensate drip as long as outside temperature is above inside temperature.

That is not visible dirt; that was never the issue. It’s about germs, bacteria, fungi...

There is a drain in every [Kontrollierte-Wohnraumlüftung] that drains condensate – and condensate only occurs when the dew point is reached. However, this practically never happens in the [Kontrollierte-Wohnraumlüftung] system (that's why there is also a dry trap, because it is used too little).

And a heat exchanger with moisture recovery (which I have) is made of a material that does not allow bacteria/germs to grow – bound salt is the keyword here.

In conventional (cross-)heat exchangers, there is no contact between supply and exhaust air...

So you haven't quite got it right yet.

But the mystery is solved. Almost the entire summer moisture condenses in the pipes. Not only in the WT does the air cool down, but after that the warm and fully saturated air also adjusts to the ambient temperature. So water condenses in the pipes during summer. Therefore, it is logical that the pipes gradually become contaminated even without construction defects.

And that is probably what happened in the said model house. After 2 summers, the critical threshold was simply exceeded. An ozone cleaning of all pipes over several hours killed the germs. Now the system can supply the sellers, visitors, architects, etc. with more hygienic, germ-free air for another 2 years.

No, it is not, because there is no riddle.

Again: Dew point is the magic word... You simply have no idea, which you keep cementing.

Especially since in the theory the pipes would be recontaminated after one day of ozone treatment - you do not understand your own theses...

30 degrees warm air with 75 percent rH has a dew point of 25.1 degrees. So if the air goes into the pipes at 23 degrees after the WT, then you have a permanent 100 percent rH there.