Page 24
V-TYPICAL OPERATING CHARACTERISTICS
A-Blower Operation and Adjustment
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 19)
Temperature rise for EL280DFE 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.
FIGURE 19
Return
Supply
Temperatures
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
C-External Static Pressure
1 - Tap locations shown in figure 20.
2 - Punch a 1/4” diameter hole in supply and return air ple
nums. Insert manometer hose flush with inside edge of
hole or insulation. Seal around the hose with perma
gum. Connect the zero end of the manometer to the
discharge (supply) side of the system. On ducted sys
tems, 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 blow
er 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.
FIGURE 20
EXTERNAL STATIC PRESSURE
Supply Duct Static
Return Duct Static +
Total Duct Static =
(dry coil)
Return
Supply
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