7
Ducting System
To build an airtight and durable ducting system, we recom-
mend that the ducting system be made from spirally
flanged pipes using fittings with a rubber ring seal.
To keep the noise level from the unit satisfactorily low, al-
ways mount silencers on the supply air and extract air duct-
ing systems between the unit and the first air intake and ex-
tract valves.
To prevent the air intake and extract valves from generating
any noise, it is recommended that air speeds in the ducting
be kept sufficiently low.
When place is found for fresh air and discharge air roof
cowls/air gratings, avoid short-circuiting the two air
streams so that the discharge air is sucked back in.
To achieve maximum comfort in the dwelling, it is recom-
mended that roof cowls/air gratings be placed on the north-
ern or eastern side of the building.
Minimum distance be-
tween roof cowls/air gratings: 3 m.
Insulation of Ducts in Cold Spaces
To take advantage of the high recovery potential of the
units (efficiency), it is necessary to insulate the ducts
properly.
Genvex recommends, as follows:
Supply Air and Extract Air Ducts
To minimise heat loss from the ducting system in cold lofts,
insulate the supply air and extract air ducts with a minimum
of 100 mm insulation. If insulation form
alternative (A) is used, it is recommended that it takes the
form of
two layers of 50 mm lamella mats with paper or foil exter-
nally and staggered joints between the two layers. If the
ducts are laid on the rafter foot,
alternative B may be used. The insulation must always be
tightly packed around the ducts.
Fresh Air and Discharge Air Ducts
It is recommended that fresh air and discharge air ducts be
insulated with a minimum of 50 mm insulation followed by
aluminium foil. The fresh air duct is insulated to prevent
warm air in the loft from heating up the fresh air in the
summer.
To avoid condensation damage, make sure that the place
where the discharge air duct passes through the roof or the
gable end is sealed well.
Refer to your local distributor for guidance on
national insulation directives.
Duct insulation, alt. A
Duct insulation, alt. B
Incorrect duct insulation
