508151-01
Issue 2104
Page 54 of 72
Typical Operating Characteristics
Blower Operation and Adjustment
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
Temperature rise for A96DS2V 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.
Return
Supply
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
Figure 50. Temperature Rise
External Static Pressure
1.
Tap locations shown in Figure 51.
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 0.8” W.C. For cooling speed (second-stage
cool speed) external static pressure drop must not be
more than 1.0” W.C.
4.
Seal the hole when the check is complete.
Supply Duct Static
Return Duct
Total Duct Static =
(dry coil)
Return
Supply
High “+”
Low “-”
+
−
or
Figure 51. Static Pressure Test