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
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
S
Stefan0013 Mar 2023 19:41RotorMotor schrieb:
I wouldn’t turn off a central mechanical ventilation with heat recovery. Ypsi aus NI schrieb:
Turning off mechanical ventilation with heat recovery is definitely not what it was designed for... Huh?
The purpose of mechanical ventilation with heat recovery is to ensure "good" indoor air quality. To me, that includes three factors: temperature, humidity, and odors.
If you don’t have issues with temperature or odors, just turn it off if that solves your problem.
If there are no further arguments here as to why it shouldn’t be turned off, I would start with that first before wasting energy unnecessarily. (Running it without need is also wasteful).
Otherwise, please leave all the lights on too—turning them off surely isn’t what it was designed for either 😉
R
RotorMotor3 Mar 2023 20:40Stefan001 schrieb:
Huh?
The purpose of controlled residential ventilation is to ensure "good" air quality. To me, that includes three things: temperature, humidity, and odors. CO2 is also an important factor.
However, it cannot be seen or smelled.
It can be measured, but that is quite expensive.
It is simpler and more cost-effective just to keep the ventilation running.
Stefan001 schrieb:
If you don’t have problems with temperature or odors, then feel free to turn it off if that solves your issue.
If there are no further arguments here for why it shouldn’t be turned off, I would start with that before wasting energy unnecessarily. (Running it without need is also a waste). The most important argument was already mentioned by Tolentino.
When air stands still in the ducts, dust, moisture, and consequently mold as well as other unwanted substances can accumulate.
This is especially problematic with floor outlets or air ducts exposed to cold temperatures.
And regarding CO2, see above.
Stefan001 schrieb:
Otherwise, please leave all lights on as well, turning them off is certainly not intended 😉 This is a particularly bad comparison.
For lighting fixtures, the number of switching cycles and their lifespan are specified.
This shows that switching on and off is explicitly planned.
Our ventilation system (Recovair) can’t even be turned off.
You have to unplug it to change the filter.
Y
Ypsi aus NI3 Mar 2023 21:33Since I don’t have a range hood yet and we really enjoy fresh air, turning off the mechanical ventilation system is definitely not an option.
We will probably just call Zehnder next week to ask how much an enthalpy exchanger can help increase humidity.
We will probably just call Zehnder next week to ask how much an enthalpy exchanger can help increase humidity.
S
Stefan0013 Mar 2023 22:42Tolentino schrieb:
It’s simple: if air isn’t regularly circulated through the ducts, condensation will eventually form, which together with dust creates an ideal breeding ground for mold.
So, even when on vacation, it’s better to keep the system running at least at a minimum level. RotorMotor schrieb:
The most important point was already mentioned by Tolentino.
If air remains stagnant in the ducts, dust, moisture, and thereby mold and other unwanted substances can accumulate.
This is especially problematic with floor vents or air ducts exposed to cold conditions.
Our (Recovair) unit can’t even be turned off.
You have to unplug it to change the filter. Well, I’m not arguing to keep it running all the time, but to reduce the operation. For example, it could run for 2 hours, then be off for 2 hours. Or, since cooking was brought up: switch it off for 4–5 hours at night and run it during the afternoon… whatever fits your routine best.
At the same time, I believe the mold argument is incorrect here: we’re specifically talking about cases where the humidity is too low. So what moisture would condense in this situation? Besides, ventilation ducts shouldn’t be touching cold pipes. In a single-family house, they’re usually installed 95% of the time in the ceiling, probably right next to the underfloor heating system 😉
Dust accumulation: yes, dust can collect on floor vents. But from there? It surely doesn’t get sucked back into the vent.
As for inlets, dust only enters when the ventilation is running (I’m not aware of any floor inlets).
My ventilation system has dedicated control programs to manage this. Even better, the humidity of the outgoing air is monitored! If it drops too low, the ventilation can automatically switch off. This is actually a feature designed by the manufacturer.
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