Heat recovery unit RDAF - Technical manual
19
FläktGroup DC_9349GB_20190326_R4
We reserve the right to make changes without prior notice
ADJUSTMENT
FLOW ADJUSTMENT
The speed of the fans is adjusted independently of each other.
NOTE! Flow deviations of up to 25% may occur when
this measurement method is used on a unit with a
rotary heat exchanger. The measured flow values should
only be regarded as indicative. Always perform control
measurement in the supply and extract air devices.
A
F
T
U
Adjustment of air flow and temperature may only be carried out by an
installation engineer or service personnel.
Wrongly adjusted air flows may result in increased
energy consumption and damage to the building.
AIRFLOW CALCULATION
The unit is equipped with four measurement points as per figure 16
above. Measuring the pressure difference,
D
p
m
in Pa over the rotor
gives the total supply air and extract air flows. The air flow q in l/s is
determined using the following formula:
q = 1.3 x
D
p
m
where
D
p
m
= measured pressure in point T – measured pressure in
point U or: where
D
p
m
= measured pressure in point F – measured
pressure in point A
PLANNING ADVICE
In a rotary heat exchanger it is not possible to completely eliminate
leakage between supply air and extract air. Air leakage at the seals is
minimised by keeping the pressure difference between the supply air
and extract air ducts as small as possible.
Also check the pressure balance between supply air and extract air.
Lower pressure on the supply air side can result in the transfer of
moisture and odour. This is especially important if Forced mode is
used.
The pressure at point T should be higher than at point F.
The pressure at point U should be higher than at point A.
T = Supply air F = Extract air
U = Outdoor air A = Exhaust air
