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16
PA-Series
ERV
INSTALLATION
NOTE: The leakage
volume is shown
here as a function
strictly of static pressure
differenece, not overall
airflow volume.
1.5 SYSTEM DESIGN—STATIC PRESSURE DIFFERENTIAL
Strong static pressure differences can result in air leakage from one airstream to the other
within the energy-recovery assembly.
When the Average Static Pressure Difference between the two airstreams is greater than 1",
you may need to account for leakage airflow in your blower selection.
1.5.1 Determining Average Static Pressure Difference
1. Lay out the design of the system specifying ducts, blowers, and all other components that
create static pressure differences.
2. Determine the static pressure conditions at the inlet and outlets of the ERV.
3. Calculate the Average Static Pressure Difference using the following formula:
Average Static Pressure Difference = [(SPoa + SPfa)/2] - [(SPra + SPea)/2]
where:
SPoa is the static pressure at the outside air inlet to the cabinet;
SPfa is the static pressure at the fresh air outlet from the cabinet;
SPra is the static pressure at the return air inlet to the cabinet;
SPea is the static pressure at the exhaust air outlet from the cabinet.
1.5.2 Evaluating Leakage Volume
Determine leakage volume from Figure 1.5.0 below. Leakage will be from the airstream at
higher static pressure to the airstream at lower static pressure.
In Push-Push and Pull-Pull blower layouts, leakage volume is almost always negligible. It should
be considered in other blower layouts and may require adjustment of the designed blower
operation points.
FIGURE 1.5.0 LEAKAGE VOLUMES
