Condensing Unit & Heat Pump R410A Service Manual

124
SERVICING
4. Consult proper air handler airow chart for quanty of air
(CFM) at the measured external stac 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 negave probe above
the coil.
2. A direct reading can be taken of the stac pressure drop
across the coil.
3. Consult proper table for quanty of air.
STATIC PRESSURE DROP
If the total external stac pressure and/or stac pressure drop
exceeds the maximum or minimum allowable stacs, check for
closed dampers, dirty lters, undersized or poorly laid out duct
work.