ᐅ Unfinished ventilation system (mechanical ventilation with heat recovery), noise disturbance when sleeping in the room below?

Hello everyone,

The installation of the controlled residential ventilation system was planned for our attic. This way, the ducts can be better distributed to the rooms below, and we saved space in the utility room.

Our bedrooms are located on the upper floor (master bedroom, walk-in closet, two children’s rooms, and bathroom). The ceiling to the attic is a wooden beam ceiling with OSB boards, which is insulated but naturally does not provide as much soundproofing as a conventional concrete ceiling on the ground floor. The intended location for the unit is directly above the bedroom. The intake opening is planned to face the gable side. On this side, there is also a children’s room.

Now, I am a bit concerned about noise. I’m wondering if the operation noise of the controlled ventilation system might disturb our sleep at night, or if it is usually quiet enough not to be noticed?

Relocating the system to the other gable side would be possible (there is the bathroom and another children’s room on that side), so we would position the ventilation unit directly above the bathroom, hoping that the noise would then not be heard in the second children’s room.

The disadvantage is that the chimney is also located on this gable side, connected to a wood stove. Could it be possible that, depending on weather conditions and chimney draft, the intake opening of the controlled ventilation system might draw in exhaust gases from the chimney?

Has anyone else installed the controlled residential ventilation system in the attic (within the insulated building envelope)?

Andre8999 schrieb:
inside the insulated envelope

This is important... everything else is practically negligible... However, I would rather position the system above the bathroom... you can also move the intake opening a few meters (yards) away...

But it’s best to ask Sebastian79 about that, he also installed his system in the loft.

I have my mechanical ventilation system installed in the attic as well. Between the system and the living space below, there are drywall panels, beams with insulation (in my case, double-layered—insulation on the ceiling and the entire roof is also insulated), followed by OSB panels.

In our house, the unit is located above the children's bedrooms, but you can’t hear anything unless the “party mode,” meaning the highest fan speed, is activated. You just need to make sure that the minimum duct lengths specified by the manufacturer for the rooms below are followed.

My system isn’t fully within the insulated envelope – we have 60mm (2.4 inches) of added roof insulation, but the main insulation ends at the collar beam level.

I started wrapping the pipes there, but eventually gave up because it’s really fiddly. So far, the temperatures near the roof peak are almost the same as on the upper floor – I’ll just keep monitoring it.

The system is installed centrally on the north gable, where the air intake is also located. Unlike the exhaust air, the supply air is somewhat quieter. Directly below the unit is our bathroom, and next to that is our bedroom.

We don’t live here yet, but I don’t hear the unit itself – only in complete silence can I hear a faint airflow, because we have two ducts connected to one valve in the master bedroom. What’s more bothersome, though, is something else – and that even at the rated ventilation level. I still need to experiment to find a good setting or programming.

Especially since the rated ventilation uses almost 120 watts per hour.

Thank you all for the answers! I will proceed with the installation and check whether the fresh air intake needs to be in the center of the gable (the controlled mechanical ventilation unit is wall-mounted in the center of the gable) or if it can also be routed to the side, further away from the chimney.

I don’t hear any drafts, but I can definitely hear the device in the equipment room (not in the adjacent room).