FIGURE 22
STATIC PRESSURE
TEST
MANOMETER
G24M UNIT
Page 19
FLAME SIGNAL TEST
FIGURE 21
IGNITION
CONĆ
TROL
SENSE"
TERMINAL
SENSOR
WIRE
D.C. MICROAMP
METER
FLAME
SENSOR
RAM CONTROL
SHOWN
Flame signal from the Ram control may rise above 5 microĆ
amps for the first few seconds after ignition then level off within
the range.
WARNING
Fire and explosion hazard.
These instructions MUST be followed exactly.
Can cause a fire or explosion resulting in property
damage, personal injury or loss of life.
V-TYPICAL OPERATING CHARACTERISTICS
A-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 subĆ
base fan switch. With fan switch in ON position, blower
operates continuously on low speed. With fan switch in
AUTO position, blower cycles with demand or runs conĆ
tinuously while heating or cooling circuit cycles.
3 - In all cases, blower and entire unit will be off when the
system switch is in OFF position.
B-Temperature Rise
Temperature rise for G24M 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 AIR TEMP. RISE
°
F" listed in the unit rating plate.
To Measure Temperature Rise:
1 - Place plenum thermometers in the supply and return
air plenums. Locate supply air thermometer in the first
horizontal run of the plenum where it will not pick up raĆ
diant heat from the heat exchanger.
2 - Set thermostat to highest setting.
3 - After plenum thermometers have reached their highĆ
est and steadiest readings, subtract the two readings.
The difference should be in the range listed on the unit
rating plate. If the temperature is too low, decrease
blower speed. If temperature is too high, first check
the firing rate. Provided the firing rate is acceptable, inĆ
crease blower speed to reduce temperature. To
change blower speed taps see the Blower Speed Taps
section in this manual.
C-External Static Pressure
1 - Measure tap locations as shown in figure 22.
2 - Punch a 1/4" diameter hole
in supply and return air pleĆ
nums. Insert manometer
hose flush with inside edge
of hole or insulation. Seal
around the hose with perĆ
magum. Connect the zero
end of the manometer to the
discharge (supply) side of the system. On ducted sysĆ
tems, connect the other end of manometer to the reĆ
turn duct as above. For systems with non-ducted reĆ
turns, leave the other end of the manometer open to
the atmosphere.
3 - With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blowĆ
er motor speed to deliver the air desired according to
the job requirements.
4 - External static pressure drop must not be more than
0.5" W.C.
5 - Seal around the hole when the check is complete.