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Installation of External Vents to MVHR unit
• We provide MVHR roof vents suitable for slate and tiled roofs.
•
It is important that the airflow is not restricted.
• MVHR units using ductwork up to 150mm diameter require a roof vent with
an airflow of 20,000mm
2
and have a rain cowl to prevent water or snow being
brought in. (Standard vents are designed for normal extraction only, not air
input to an MVHR).
•
Do not use flush mounted roof vents without a cowl as unit warranty will be
void.
•
We recommend the installation of an in-line drain with waterless trap be fitted
to the air extract roof vent to prevent water damage to the unit
•
In addition, roof vents must be installed at a higher level than the MVHR unit
or condensation will form in the pipework .
Wall Vents
•
There should be a small fall to the external wall vents,
the vents are required to be installed at a minimum of 1.5
meters apart to prevent air contamination.
•
All external pipework to the MVHR unit should be insulated
and final connections by a flexible pipe connector.
• Ductwork from the unit should be kept to a minimum and
preferably not exceed 5 meters
The most popular provided Stainless Steel cowls come with a mesh. Please
carefully remove the mesh if the cowls do not have easy access for cleaning.
Optional PVC louvred vents can be used on walls or soffits but are more
susceptible for rain or wind noise to enter the system.
Roof Vents
Flat roof vents are widely
available but due care has to
be taken to ensure the airflow
capacity is not restricted and
are suitable for air supply.
On larger units requiring
over 20,000m
2
you can
use a commercial stack or
alternatively double up and
install two roof vents per pipe.
A short section of Insulated
flexible ducting will be required
to install roof vents and ensure
that it is pulled tight and is not
crushed. This also should be
supported to prevent deformation
over time.
Contact Us! - Website: www.bpcventilation.com - Tel: 028 2827 5150 - Email: technical@bpcventilation.com
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Please note that the Stainless Steel cowls are not suitable for areas of sea salt
and PVC louvred vents should be fitted.