Hello dear forum,
We are using a Zehnder ComfoAir Q350. Unfortunately, it has had some issues with the "installation" from the start. First, the wrong settings were applied, and then the interior doors were too airtight. After the ventilation technician visited about five times since summer, it is now running reasonably well. Although the air quality in the bedroom still feels as if we have no ventilation, according to the technician everything is set up correctly.
Now that the weather has turned quite cold recently, we have noticed significant condensation on the windows in some areas. Especially in the bedroom and also in the open living-dining area. The technician said this is normal in a new building – however, due to the ventilation system and underfloor heating, we only have about 25% humidity. With an additional humidifier (Venta), we manage to reach almost 40%.
Question: Shouldn’t a ventilation system automatically remove moisture inside the house and prevent the windows from fogging? Is it possible that the ventilation system is still not correctly adjusted? How can something like this be tested?
Information about the picture:
- Bedroom (16 m² (172 sq ft))
- Room temperature approx. 18-19°C (64-66°F)
- Two adults and occasionally a toddler (2.5 years)
- 1x supply air (Zehnder)
Thank you very much!
Bastian
We are using a Zehnder ComfoAir Q350. Unfortunately, it has had some issues with the "installation" from the start. First, the wrong settings were applied, and then the interior doors were too airtight. After the ventilation technician visited about five times since summer, it is now running reasonably well. Although the air quality in the bedroom still feels as if we have no ventilation, according to the technician everything is set up correctly.
Now that the weather has turned quite cold recently, we have noticed significant condensation on the windows in some areas. Especially in the bedroom and also in the open living-dining area. The technician said this is normal in a new building – however, due to the ventilation system and underfloor heating, we only have about 25% humidity. With an additional humidifier (Venta), we manage to reach almost 40%.
Question: Shouldn’t a ventilation system automatically remove moisture inside the house and prevent the windows from fogging? Is it possible that the ventilation system is still not correctly adjusted? How can something like this be tested?
Information about the picture:
- Bedroom (16 m² (172 sq ft))
- Room temperature approx. 18-19°C (64-66°F)
- Two adults and occasionally a toddler (2.5 years)
- 1x supply air (Zehnder)
Thank you very much!
Bastian
S
Steffen8022 Jan 2019 14:10Mottenhausen schrieb:
Don’t overcomplicate it: you’re adding extra humidity to the air, but expect the mechanical ventilation with heat recovery to quickly exhaust this additional moisture before it condenses on surfaces with temperatures below the dew point? A local electronic humidifier works very… digitally; if it measures too low, it briefly raises humidity to over 60% in its immediate area, assuming this will mix evenly to about 40% throughout the room. In practice, this doesn’t happen: the humidifier’s moisture cloud moves upward along the natural air circulation toward the ceiling and then falls back down along the windows, where it can easily condense.
How warm are the rooms at night where condensation occurs? If you want to maintain 40% relative humidity, you also need to ensure the necessary room temperature is maintained around the clock, at least 22°C+ (72°F+).Nonsense! We have a Q450 with an enthalpy exchanger and two large Venta humidifiers (Lw45) currently in use because I want a humidity level above 45%. We achieve that even at -10°C (14°F) outside and with daily use of the fireplace. Usually, we have between 45 and 50%, which is ideal. I have never seen wet windows here—not even in the bathroom after showers with humidity at 90%.
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baschdieh22 Jan 2019 14:23Lumpi_LE schrieb:
These are only the values from the bedroom (as I understood it). The values for the entire house are certainly quite different, but a simple mechanical ventilation system cannot differentiate that.The screenshot was indeed only from the bedroom. However, in my view, the values in the living area do not look very good either.
We have about 50m2 (kitchen, dining room, living room) including 2 supply air and 1 exhaust air vent. Our floor is completely open – meaning the staircase and entrance area also have no doors and act as airflow passages.
From around 4:30 PM, there were three people in this open area. At about 9:00 PM, I then opened the window to ventilate.
Steffen80 schrieb:
Nonsense! We use a Q450 with an enthalpy exchanger and two large Venta air humidifiers (Lw45) because I want indoor humidity above 45%. We achieve that even with temperatures of -10°C (14°F) outside and daily fireplace use. Usually, we maintain between 45 and 50%, which is ideal. I have never seen our windows get wet, not even in the bathroom after showers with 90% humidity. I can only agree with that. The air gets too dry for us in winter as well, but thanks to Venta it’s bearable. Still, our windows never fog up.
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baschdieh23 Jan 2019 12:30So, the ventilation system is probably the culprit. I found out that the system apparently stops supplying fresh air around 4:00 PM. The Zehnder display then shows "Frost Disbalance" – in the status, I saw that the "Frost Protection" is set to "100%" and the fresh air supply to "0%". In the evening, I left the door to our bedroom open, which resulted in the windows staying dry.
After various research, I have now found out that I apparently need a pre-heating coil to ensure the system operates even at below-freezing temperatures. Can this be confirmed?
After various research, I have now found out that I apparently need a pre-heating coil to ensure the system operates even at below-freezing temperatures. Can this be confirmed?
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