Is moisture recovery in controlled residential ventilation sensible?

# Mycraft:

When choosing the systems, I have to agree with you, although there are huge price differences for the heat exchangers. For my Paul Novus 300, one costs about 800 euros (so not quite half), while with other manufacturers it goes for almost double.

I also understand that the air does not get more humid, but the effect of a geothermal exchanger, which makes the air drier and thus more pleasant in summer, is weakened. I would still let the moisture condense in the brine (or air) heat exchanger and then "humidify" it again in the device. Makes no sense to me...

In winter, all ventilation systems dry out the houses. But that also happens if I properly ventilate through the windows. The effect with the heat and moisture exchanger is just delayed in the end, isn’t it?!?

If you have already looked more closely into the topic, maybe you can tell me what besides water is also recovered through these special membranes. I know it depends on the size of the molecules what passes through.

The membranes are coated and kill all germs/bacteria - the air will not be more contaminated than your breathing air from outside.

And why should the effect be delayed - the people in the house sweat/breathe, so this humidity is to some extent regained.

So if a heat exchanger afterwards costs almost half of the new system... in my eyes, it is simply nonsense to first install one without and later with moisture recovery... that is just a waste of money... but well, as is well known, one learns from mistakes...

The membrane contains a high proportion of salt u and absorbs the water vapor like a sponge. On the cold air side, the water evaporates at the membrane surface and is taken up by the drier air flow. The salt is chemically bound to the membrane material and is neither dissolved nor flushed out in the water. The membrane transports water molecules because of their high dielectric (non-conductive) constant and small dimensions. Microorganisms cannot penetrate the membrane due to their larger size compared to water. Additionally, the high salt concentration in the membrane acts antibacterially. Bacteria, yeast, mold, and all microorganisms die on the membrane surface.

So I consider the enthalpy heat exchangers to be absolutely unnecessary.

We also had the problem with somewhat dry air. I simply reduced the air exchange rate, assigning different speeds to the individual ventilation levels.

This way, in the cold/dry winter, we reach 40-45% instead of 30-35% relative humidity.

Every person is simply different... for one, the 30% doesn't matter, and another is already crying at 40... we get by quite well with a simple heat exchanger, for example, but when it comes close to 30%, I do occasionally wish for a moisture recovery... but those are usually only a few days a year...

... however, when it gets close to 30%, I do wish for a bit of moisture recovery now and then... but those are usually only a few days a year...

And for those few days a year, we have a small portable humidifier. It mostly stands in the bedroom and runs for a while before going to bed.
The missus has a few issues with dry air due to her allergies and such.