ᐅ Ventilation system in summer?

The figures are always given as “up to” because the efficiency depends on the volume flow. You can check on passiv.de, they have a helpful list of devices certified by them.

I can provide some specific values...

With a central system at approximately 150 cubic meters (5300 cubic feet) and an outside temperature of 30°C (86°F), I have a supply air temperature of 26°C (79°F).

That’s not much cooler, and the house still heats up... after a week of 30°C (86°F) outside, the indoor temperatures approach the outside temperatures as well. But as I mentioned at the beginning, our system runs continuously... because I prefer to sweat with fresh air rather than have slightly cooler air that feels “heavy.”

Mycraft schrieb:
I can provide specific figures...

That sounds reasonable and should be believable to anyone.

Perhaps the small temperature difference reduces the heat recovery efficiency, so instead of recovering 90% of the warm air, only about 50% is recovered? This could explain Mycraft’s observation, although it is purely speculative and not based on any evidence.

Ultimately, it comes down to personal comfort, fresh air versus less heating.
For example, you could run the system at the lowest setting during the day to ensure minimum air exchange, especially if you’re spending most of the time outside in such weather. Then, when it gets cooler in the evening, increase it to level 2 or 3.
That’s at least how I would try it for us.

Kaspatoo schrieb:
You could, for example, run it at the lowest setting during the day for minimum air exchange, especially if you are mostly outside in this kind of weather. Then, when it gets cooler in the evening, you can increase it to level 2-3.

However, this usually requires going to the system in the mornings and evenings...

P.S. Now the supply air is 28°C (82°F) at 31°C (88°F) outside

Mycraft schrieb:
P.S. now the supply air is 28°C (82°F) at 31°C (88°F) outside

Haha, here yesterday it was 30°C (86°F) outside with a supply air temperature of 20.5°C (69°F).

Geothermal heat exchanger rules...

SCNR

So temperature-wise, we have no problems here. The downside, however, is that the controlled ventilation system inevitably brings some humidity into the house. The dew points are not reached either in the geothermal heat exchanger or in the ventilation unit’s heat exchanger. Thus, no condensation occurs and indoor humidity rises to values of up to 55% in the basement and 60% elsewhere.
It’s still manageable but borderline for me.
I’m already considering building a bypass for a dehumidifier that I could run for a few hours at a time.

To the original poster:
Of course, you keep the controlled ventilation running in summer. Although it does bring some heat into the house, it’s much less than leaving a window open. And at night, you can still ventilate normally through open windows if you want.

Best regards,

Andreas

At night, the bypass should ensure that cooler air is brought into the house.
Enthalpy heat exchangers not only retain moisture but also limit it. Perhaps this is worth taking another look at.