ᐅ Controlled residential ventilation in winter, dry air—what can be done about it?

Note: The enthalpy heat exchanger usually cannot be added onto the existing (mostly crossflow) heat exchanger; instead, the existing one is replaced by it. Therefore, you save money by installing it from the start. Retrofitting later means buying two heat exchangers...

Tommes78 schrieb:
Well, as I said, at the moment I’m rather disappointed with the mechanical ventilation system with heat recovery; so far, it only works reasonably well during transitional seasons.

Well, you know, it’s not just about the technology itself, but also about how you use it! It’s well known that a mechanical ventilation system with heat recovery often produces (too) dry air in winter. That’s why you can retrofit an enthalpy heat exchanger—or, as mentioned here already, it’s best to install one right from the start.

And who keeps their windows open all summer? No one! Because otherwise warm air gets inside. And that’s exactly what happens if your ventilation system is running continuously. So use it smartly and only run it at night during summer. You’re usually not home much during the day in summer anyway, so constant fresh air intake isn’t necessary. And if you do spend more time inside, you can just open a window the old-fashioned way.

Sorry for the blunt words. But the technology itself isn’t necessarily to blame for the problems. It always depends on how you use it.

In summer, the heat exchanger causes the house to warm up more slowly through ventilation than it would with simply opening windows. In fact, our house feels cooler compared to similar buildings without a mechanical ventilation system (at least based on our limited experience). Of course, there is a limit: after several weeks of very hot weather, with warm temperatures at night as well, the indoor temperature will eventually equal the outdoor temperature, regardless of having mechanical ventilation or not. At that point, only active cooling (for example, using an air conditioner) can help.

From the beginning, we have used an enthalpy heat exchanger and currently (in winter) experience relative humidity levels of about 45%.

After all, with controlled residential ventilation you at least have the POSSIBILITY to use something like an enthalpy heat exchanger. Without controlled residential ventilation, we currently have humidity levels between 27% and 32%.

In the past (30 years ago), we had water containers on the radiators (google: "radiator humidifier evaporative ceramic"). Dry air is therefore not a new phenomenon, so your statement about controlled residential ventilation is indeed correct.

We have an enthalpy heat exchanger and humidity levels never drop below 40%, which is very comfortable. We bought it right from the start. However, if the humidity were to drop to 30%, I would definitely bite the bullet and retrofit it, even if it costs 1000€ (about $1100). It simply makes the living environment much more pleasant…