Condensing Unit & Heat Pump R410A Service Manual
124
SERVICING
4. Consult proper air handler airow chart for quanty of air
(CFM) at the measured external stac pressure.
Supply Static
+ .20” wc
Return Static
- .30” wc
S-204 COIL STATIC PRESSURE DROP
1. Using a dra gauge (inclined manometer), connect the posi-
ve probe underneath the coil and the negave probe above
the coil.
2. A direct reading can be taken of the stac pressure drop
across the coil.
3. Consult proper table for quanty of air.
STATIC PRESSURE DROP
If the total external stac pressure and/or stac pressure drop
exceeds the maximum or minimum allowable stacs, check for
closed dampers, dirty lters, undersized or poorly laid out duct
work.