508187-01
Issue 2116
Page 34 of 51
Typical Operating Characteristics
Blower Operation and Adjustment
NOTE:
The following is a generalized procedure and does
not apply to all thermostat controls.
1.
Blower operation is dependent on thermostat control
system.
2. Generally, blower operation is set at thermostat
subbase fan switch. With fan switch in ON position,
blower operates continuously. With fan switch in
AUTO position, blower cycles with demand or runs
continuously while heating or cooling circuit cycles.
3.
Depending on the type of indoor thermostat, blower
and entire unit will be off when the system switch is in
OFF position.
Temperature rise for A80UH2E / 80G2UHE(L) units
depends on unit input, blower speed, blower horsepower
and static pressure as marked on the unit rating plate.
The blower speed must be set for unit operation within the
range of “TEMP. RISE °F” listed on the unit rating plate.
Figure 17.
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
SUPPLY
AIR
Temperatures
RETURN AIR
External Static Pressure
1.
Tap locations shown in Figure 18.
2. Punch a 1/4” diameter hole in supply and return air
plenums. Insert manometer hose flush with inside
edge of hole or insulation. Seal around the hose with
permagum. Connect the zero end of the manometer to
the discharge (supply) side of the system. On ducted
systems, connect the other end of manometer to the
return duct as above.
3.
With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blower
motor speed to deliver the air desired according to the
job requirements. For heating speed (second stage
heat speed) external static pressure drop must not be
more than 0.5” W.C. For cooling speed (second stage
cool speed) external static pressure drop must not be
more than 0.5” W.C.
4.
Seal the hole when the check is complete.
Figure 18.
EXTERNAL STATIC PRESSURE
Supply Duct Static ________
Return Duct _____
Total Duct Static = ________ (dry coil)
Duct Static
or
Supply Air
Return Air
