ᐅ Where to install ducts for controlled residential ventilation in the ceiling of the top floor

Hello,

can someone briefly explain where the ducts for a mechanical ventilation system with heat recovery can be installed on the upper floor if the house has two full stories, the top ceiling is a beam ceiling, and the roof above is either uninsulated or has only 60mm (2.4 inches) of insulation above the roof deck? If the ducts are installed above the beam ceiling, they are outside the thermal envelope; if installed within the insulation, much of the insulation’s effectiveness is lost. Also, running ducts perpendicular to the beams is difficult. How is this usually done? Thank you.

Pipes are often installed in or on the ceiling of the ground floor. The rooms on the ground floor are then connected through ceiling outlets, while the rooms on the upper floor use floor outlets (supply air) or wall outlets (exhaust air). This means the exhaust air duct coming from the ceiling is redirected and routed up the wall. At the top of the wall, there is the wall outlet. The advantage, in my opinion, is shorter distances and fewer redirections.

We have the same house type as you. In our case, the spaces between the rafters are insulated. Below that is the vapor barrier, and beneath it there is an additional 5-6 cm (2-2.5 inches) insulation layer down to the drywall ceiling. The flat ducts are installed within this layer.

Regards, Ronny

I have the pipes located in the attic space, along with the mechanical ventilation unit itself.

The attic is also unheated and only insulated with 60mm (2.4 inches) of insulation above the rafters.

The ducts need to be insulated – I have ordered 50mm (2 inches) aluminum-faced mineral wool boards for this purpose. The effort involved is manageable.

This way, you achieve the correct insulation thickness everywhere – I’m not in favor of relying on insulation at the wall or floor outlets.

Sebastian79 schrieb:

You have the correct insulation thickness everywhere – I’m not a fan of wall or floor vents though.

Why?
In our attic, we have wall vents about 20-30 cm (8-12 inches) below the ceiling. According to airflow measurements, this is completely sufficient. The 2.3-meter (7.5-foot) tall wardrobe doesn’t fit in front of them, but it would have been difficult with a ceiling vent in that spot as well.

Because distributing air from the wall using high-throw diffusers is never as effective or quiet as using ceiling-mounted swirl diffusers.

Not to mention the expense of slots and the resulting weakening of the wall, which also affects sound insulation.

I do not at all dispute that it works in terms of volume.

And I still have space for a cabinet underneath.