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nuaire.co.uk
029 2085 8400
20. 08. 19. Document Number 671887
I
nstallation and Maintenance
MRXBOXAB-ECO-LP2-C Remote Commissioning MVHR
Table 1. ADF 2010 - Extract ventilation rates.
Table 2. Whole dwelling ventilation rates.
Notes:
1. In addition, the minimum ventilation rate should be no less than
0.3 l/s per m2 of internal floor area. (This includes all floors, e.g.
for a two-story building add the ground and first floor areas).
2. This is based on two occupants in the main bedroom and a single
occupant in all other bedrooms. This should be used as the default
value. If a greater level of occupancy is expected add 4 l/s per
occupant.
Room
Min high rate
Min low rate
Kitchen
13 l/s
Total extract rate
should be at least
the whole dwelling
ventilation rate given
in Table 2.
Utility Room
8 l/s
Bathroom
8 l/s
Sanitary
Accommodation
6 l/s
Number of bedrooms in dwelling
1
2
3
4
5
Whole dwelling
ventilation rate
(l/s)
1,2
13
17
21
25
29
3.4 Ventilation Flow Rates
3.5 ADF 2010 Ventilation Calculations Design of MVHR
Systems
The MVHR system has been sized for the winter period. Additional
ventilation may be required during the warmer months and it has
been assumed that the provisions for purge ventilation (e.g. open-able
windows) could be used.
Step 1:
For any design air permeability, determine the whole dwelling
ventilation supply rate from
Table 2.
As an alternative where the design air permeability is intended to be
leakier than (>) 5m3/(h.m2) 50 Pa, allow for infiltration for all dwelling
types by subtracting from the whole dwelling ventilation supply rate
from Table 2; 0.04 x gross internal volume of the dwelling heated space
(m3).
Step 2:
Calculate the whole dwelling extract ventilation rate by
summing the individual room rates for ‘minimum high rate’ from
Table
1.
(For sanitary accommodation only, as an alternative, the purge
ventilation provisions given in ADF 2010 can be used where security is
not an issue. In this case ‘minimum high extract rate’ for the sanitary
accommodation should be omitted from the step 2 calculation).
Step 3:
The required airflow rates are as follows:
The maximum whole dwelling extract ventilation rate (e.g. boost)
should be at least the greater of step 1 and step 2.
Note that the maximum individual room extract rate should be at least
those given in
table 1
for minimum high rate.
The minimum air supply rate should be at least the whole building
ventilation rate found in step 1.
For Scotland refer to BRE Digest 398.
For further information refer to the “Domestic Ventilation Compliance
Guide”.
IMPORTANT
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.
Pre Commissioning MRXBOXAB MVHR Units
MRXBOXAB units are designed to ventilate the whole dwelling
and must not be used during site construction or the clean-up
period. Cement and plaster dust can be abrasive and can affect
fan performance and reliability. Please ensure that the filters are
checked prior to commissioning to ensure there is no build-up of
dust or debris.
While the property is drying out, very high moisture levels are likely
to occur. Therefore it is advisable that if the installation and building
works are complete the unit is left running. If the building works are
not complete please close the air valves or cover up the air valves to
prevent condensation forming in the ductwork and the MRXBOXAB
unit due to natural migration of warm air.
