Instruction Manual

508269B01Issue 2217Page 8 of 9
Blower Speed Connection
Proper air volume must be provided over the evaporator
coil. Select a blower motor speed tap that will provide 400
± 50 CFM per 12,000 Btuh of cooling capacity (wet coil).
A static pressure reading must be taken to see if the
pressure drops are within the proper range. See Figure 12
as an example to obtain an accurate reading.
To ensure accuracy, test the air on both sides of the coil.
Refer to Figure 12 for location of two test holes.
Figure 12. Static Pressure Test
LEFT-HAND AIR DISCHARGE (TOP VIEW)
SUPPLY AIR UNIT FRONT
SUPPLY AIR UNIT REAR
AIR
FLOW
TEST HOLE 1
TEST HOLE
2
SUPPLY
AIR DUCT
RETURN AIR
DUCT
Take care when drilling test holes into the furnace ange
and the duct. Drill holes away from refrigerant piping.
Test holes should be drilled where specied in order to
avoid unit damage.
CAUTION
1. Drill a 5/16” test hole in the coil case 1” from the
furnace ange (test hole 1, Figure 12).
2. Drill a 5/16” test hole into the supply air duct (test hole
2, Figure 12).
3. Connect the zero end of the draft gauge scale to the
furnace end of the coil. Insert the hoses so that 1/4”
extends inside the duct or end seal. Seal around holes
with Permagum.
4. Turn on the electrical power to the furnace and set the
thermostat to initiate a cooling demand.
5. Table 2 lists the range of air volumes and equivalent
draft gauge readings for this unit. Observe the draft
gauge 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 blower
speed. Refer to the furnace wiring diagram for blower
speed settings.
6. When the required draft gauge readings are obtained,
remove the draft gauge lines and insert snaphole
plugs into the test holes.
Cabinet
Vol: CFM
Drop: in. w.g.
Model Width in. Dry Wet
-24A 14-1/2 800 .15 .19
-24B 17-1/2 800 .09 .11
-30A 14-1/2 1000 .24 .27
-30B 17-1/2 1000 .14 .16
-36A 14-1/2 1200 .30 .39
-36B 17-1/2 1200 .16 .21
-36C 21 1200 .15 .18
-42B 14-1/2 1400 .26 .31
-42C 17-1/2 1400 .18 .21
-48B 17-1/2 1400 .25 .29
-48C 21 1600 .27 .30
-51C 21 1600 .25 .29
-60D 24-1/2 2000 .24 .30
Table 2. Air Volume/Static Pressure Drop Across Coil
Maintenance
Cleaning The Coil
The coil should be inspected twice each year and cleaned
at least once per year or more, if necessary. Indoor coil
cleaning should be performed by a licensed professional
service technician (or equivalent).
A damaged coil n can a󰀨ect equipment operation and
performance. Do not use ame, high-pressure water,
steam, or volatile cleaners on ns or tubing surfaces. If
cleaning requires the use of acidic or alkaline cleaners,
follow the manufacturer’s instructions. Thoroughly ush
cleaner from all equipment components. (Be careful
to prevent damage or corrosion of the components
connected to the system or areas surrounding the
equipment being cleaned.)
CAUTION
Do not use hydrouoric acid, alkaline, or similar chemicals
to clean coils. These chemicals are not necessary to
dissolve salt, and may damage the n coating. Acid washes
are used to dissolve oils and greases, which generally are
not present on residential applications.
Do not use alkaline washes. Alkaline washes are useful
for dissolving oxides such as zinc oxide, aluminum oxide,
and iron oxide (rust). However, these three oxides are
more corrosion resistant than base metals, so dissolving
or removing them will cause an increase in corrosion.