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24. 01. 17. Leaflet Number 671500
Installation and Maintenance
MRXBOX95B-LH1/LH2 Mechanical Ventilation with Heat Recovery & Summer Bypass
2.2 Installing Nuaire CONTRAP
In ducted ventilation systems, condensation will occur when
warm, humid air extracted from your bathroom, shower, kitchen
or utility room hits the cooler surface of the ventilation duct.
If the extracted air is sufficiently cooled, the moisture will
condense back to water and become trapped in the ducting,
potentially causing damage to the fan.
Nuaire’s CONTRAP is simply connected to the system as part
of the vertical duct run and an internal gutter within the trap
collects the moisture and then drains it out through a standard
overflow pipe to the outside. This ensures that the moisture
cannot enter a potentially hazardous area.
Use insulated ducting
By using insulated ducting, the inner duct layer stays warmer,
and therefore keeps the extracted air at a higher temperature.
This allows the water to condense outside the building and not
in the ducting.
Any air intake terminal MUST be installed in accordance
with the appropriate regulation.
As a guide, the BS5440 series of British Standards
deals with this issue and currently states that an air
intake must be at a minimum distance of 300mm from
a gas boiler balanced flue. Installers are advised to
be aware of the requirements of this standard when
installing ‘through the wall’ supply air ducting.
Similarly, supply and extract air grilles should be at
least 300mm apart.
Figure 4. Typical MVHR ducted arrangement for a loft mounted unit using the Nuaire condensation trap 125mm dia. (CONTRAP 125).
Nuaire
CONTRAP
condensation
trap.
To soil stack
or soffit vent.
Insulated.
Tile Vent.
Condensed water
forming inside
the duct
Insulated.
Insulated.
2.3 Extract/input areas
The unit is designed to extract air from all wet rooms
e.g. bathroom, kitchen, en-suite, utility room (with sink).
WC’s do not need to be ventilated if openable windows are
fitted. Supply air should be to all habitable rooms e.g. bedrooms
and lounge. Extract / input grilles should be adjustable valve
types (not supplied).
2.4 Ducting
1.
If the unit has been specified as SAP appendix Q installation
the use of flexible is prohibited. If flexible ducting is to be
used it should be kept to a minimum and should always be
pulled taught.
2. The unit is supplied with 125mm dia. outlets.
To prevent any condensation on the ducting it should be
insulated externally vapour-proof as far as the unit.
3. Ducting layout plans should be adhered to if available.
4. It is recommended that 125mm dia. or 204 x 60mm ducting be
used and the number of 90 Deg bends be kept to a minimum.
5. Ducting joints must be sealed with duct tape and/or silicone
sealant.
For further information refer to Building Regulations Part F and
BRE appendix Q website.
IMPORTANT: When using a “T” Piece to connect the CONTRAP
drainage and the MVHR drain pipework the MVHR drain
must
always be fitted before the “T” Piece
to prevent condensate
from feeding back into the MVHR system.
To SVP
“T” piece
MVHR Drain
To unit
To CONTRAP
