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XPG15 SERIES
ADDING OR REMOVING REFRIGERANT
This system uses HFC−410A refrigerant which operates at much higher pressures than HCFC−22. The pre−installed liquid
line filter drier is approved for use with HFC−410A only. Do not replace it with components designed for use with HCFC−22.
This unit is NOT approved for use with coils which use capillary tubes or fixed orifices as a refrigerant metering device.
Check airflow using static pressure reading as defined in figure 20.
AIRFLOW
INDOOR COIL
LEFT−HAND AIR DISCHARGE
(TOP VIEW)
TEST HOLES
AIR FLOW
Proper air volume must be provided over the evaporator coil. Se-
lect a blower motor speed tap that will provide 400 ± 50 CFM per
12,000 Btuh of cooling capacity (wet coil). A static pressure read-
ing must be taken to see if the pressure drop falls within the proper
range.
To ensure accuracy, air must be read from below the coil and
above the coil. See figure to the left for an example to obtain an
accurate reading.
1. Drill one 5/16" (8 mm) air test hole into the delta plate between
the coil slabs.
2. Drill one 5/16" (8 mm) air test hole into the duct above the top
of the coil.
3. Connect the
instrument for static pressure measurement
hoses
to the air entering side of coil. Insert the hoses so that
1/4" (6 mm) extends inside the duct or end seal. Seal around
holes with Permagum.
4. Turn on electrical power to the furnace and set the thermostat
to initiate a cooling demand.
5. Refer to indoor coil installation instruction for range of air vol-
umes and equivalent static pressure readings for these units.
Observe the static pressure reading. If the reading is below
the required air volume, increase the blower speed; if the
reading is above the required air volume, decrease the blow-
er speed. Refer to the furnace wiring diagram for blower
speed settings.
6. When the required static pressure readings are obtained, re-
move the test hose lines and insert snaphole plugs into test
holes.
CAUTION
Take care when drilling test holes in the furnace
flange and the duct. Drill holes away from refrigerant piping.
Test holes should be drilled where specified in order to avoid
unit damage.
Figure 20. Checking Indoor Airflow over Evaporator Coil using Static Pressure Reading
