HOME VENTILATION
3
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The R85 wall-mounted in a laundry room.
Figure A.
RECOtite pressure equalizer.
RECOtite
The ratio between the pressure in the outside air and the extract
air ducts, how clean the filters are, etc. have an effect on the
pressure differential between the upper and lower top seals at
the transition point of the rotary heat exchanger. If the pressure
differential becomes too high, the upper seals will begin to leak
and the airflows will mix with one another in an undesirable
way. In ventilation systems where there are low airflows, such
as in small homes, the pressure differential often becomes too
high and air inside the ventilation unit begins to leak from the
extract air section to the supply air section as shown in Figure A.
Normally when airflows are to be adjusted, only the supply
and extract airflows of the home are measured. If the leakage
is then too high, the actual outside air flow and the extract
airflow will deviate from the planned values and the basic
home ventilation rate may even be as much as 30% less than
planned. If the air change rate is less than anticipated, the venti-
lation system’s capacity for extracting moisture out of the home
will not be sufficient to meet the load, and moisture will begin
to accumulate inside the home. Leakage also has the adverse
effect that moisture in the extract air is conveyed back into the
home together with the supply air.
The traditional method used for compensating the pressure
differential is to increase the pressure in the extract air duct by
restricting the airflow with a regulating damper. However by
doing so, the ventilation unit can no longer reach the efficiency
promised. The airflow often becomes too low, e.g. when it is
boosted and this radically increases the amount of power con-
sumed by the fan (negatively affecting the SFP value).
A RECOtite
pressure equalizer equalizes the difference in pres-
sure between the extract air and the supply air sections, and, as
a result, no leakage flow of air occurs any longer at this point.
The leakage has been moved to the adjacent top seal, and the
leakage flow now occurs from supply air to supply air. There are
also flows below the pressure equalizer in the heat exchanger
and the heat recovery efficiency is thus not affected.
