ᐅ Building Drying: Is It Better to Turn Off the Controlled Mechanical Ventilation System in Summer?

Hello,

we want to dry out our building before moving in; also, the screed is not yet ready for covering (CM: 2.3).

We have two large construction dryers running. Should the already installed mechanical ventilation system with heat recovery (Zehnder Q450) be turned off or run at maximum during the current temperatures? (Currently just under 20°C (68°F) and about 80-90% humidity.)

Or is it better to run it at maximum only in the evening/night when the air is cooler? (At night around 10°C (50°F))

Best regards,
Barossi

I believe that whether or not your mechanical ventilation system with heat recovery is running doesn’t really affect air dehumidification. At the humidity level you’re dealing with (30%), hardly any moisture can be extracted from the air. Any remaining moisture can easily be handled by your construction dryers. If the humidity varies significantly from room to room, you might consider running the mechanical ventilation system to circulate the air; otherwise, I would switch it off to save energy and enjoy the still-clean filters.

I thought the controlled residential ventilation system should only be turned on after the building drying process, to avoid contamination and because the air inside the system is continuously humid at the beginning... I believe this has been discussed somewhere before.

Well, the house is no longer really damp, but the screed is still acting up (CM: 2.3) and I wanted to support the dehumidifiers a bit with the mechanical ventilation with heat recovery.
What else should happen apart from replacing the filters due to dust?

I have just read that in summer the mechanical ventilation with heat recovery can additionally bring humid air into the building.

I would not want construction dust inside the duct system or especially the heat exchanger. Have a look at the manual; there might already be a warranty exclusion related to this.

At the very least, I would cover all exhaust air vents individually with filter mats. Depending on the amount of dust, these would need to be replaced quite regularly.

I’m not worried about that. The work is complete, and the floor has been vacuumed. We are just waiting for the screed to dry. No more dust is generated. I wanted to complement the drying fans with the controlled residential ventilation system.