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V-TYPICAL OPERATING CHARACTERISTICS
A-Blower Operation and Adjustment1
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 sub
-
base 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.
B-Temperature Rise (FIGURE 55)
Temperature rise for ML196DF units depends on unit in
-
put, 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
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
FIGURE 55
C-External Static Pressure
1 - Tap locations shown in FIGURE 56.
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
external static pressure drop must not be more than
0.5” W.C. For cooling speed external static pressure
drop must not be more than 0.8” W.C.
4 - Seal the hole when the check is complete.
EXTERNAL STATIC PRESSURE
Supply Duct Static
Return Duct
Total Duct Static =
(dry coil)
Return
Supply
High “+”
Low “-”
+
−
or
FIGURE 56
D-Blower Speed Taps
Blower speed tap changes are made on the integrated
control. See figure 3. The heating tap is connected to the
“HEAT” terminal and the cooling tap is connected to the
“COOL” terminal. On all units the continuous blower tap
is connected to the “FAN” terminal. Unused taps must
be secured on two dummy terminals labeled ”PARK. To
change out existing speed tap, turn off power and switch
out speed tap with tap connected to “PARK”. See blower
speed tap table on unit diagram for motor tap colors for
each speed.
