ᐅ 20% Relative Humidity in a KfW 40+ New Build

Created on: 3 Mar 2023 08:43
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Ypsi aus NI
Hello everyone, the title already describes the problem. Approximately 20% humidity in all living and sleeping rooms. We moved in about two weeks ago. That can’t be normal, right? I expected such low humidity only after 2-3 years, but not right from the start...

The first night in the house was really horrible. On top of that, we have been dealing with colds and coughing the whole time. We now have a humidifier running all night in the bedroom (starting in the evening, about 12 hours total) and wake up with around 35-40% humidity.

Could something be set incorrectly in the mechanical ventilation system with heat recovery, or is this low humidity normal in a new house?

What can we do? Apart from the bedroom, we don’t notice it being a problem in any other room. Enthalpy exchangers are supposed to increase humidity by a maximum of 5%, right?!

Thanks for your feedback and best regards
A
Apolyxo
20 Jun 2023 13:25
Ypsi aus NI schrieb:

9% was then the decisive reason

Okay, but 40° Celsius (104°F) is no problem? 😀
Tolentino20 Jun 2023 14:21
In the sun, it’s actually not that much. I estimate that corresponds to about 24°C (75°F) in the shade?
mayglow20 Jun 2023 14:35
Tolentino schrieb:

In the sun, it's actually not that much. I estimate it's about 24°C (75°F) in the shade?

However, when displaying relative humidity, one should keep in mind that it depends on the temperature and can be distorted if the sun is directly hitting the sensor, right?
Tolentino20 Jun 2023 14:52
That's correct.
9% at 39°C (102°F) corresponds to about 20% at 24°C (75°F).
~4.4g/m³
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Ypsi aus NI
20 Jun 2023 15:11
Fortunately, we have air conditioning. When the hygrometer is in the shade, it shows about 24 degrees Celsius (75°F). However, it doesn’t feel that warm to us. The air conditioner displays 24 degrees Celsius (75°F) as well, but it feels comfortable and sometimes even cool. The KNX push button, hygrometer, and air conditioner all report roughly the same value: around 24 degrees Celsius (75°F).
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Ypsi aus NI
20 Jun 2023 15:15
The low humidity causes another problem: electric shocks! We keep getting shocks from our chairs. This never happened in the old house (also with tiled floors).

Yesterday, I had the humidifier running at full power in the bedroom with the door closed. I fell asleep while putting the child to bed. At 11 p.m., the smoke detector went off at 85% humidity... This never happened before... It’s just annoying.

WHEN is the EWT coming????