FIGURE 13
STATIC PRESSURE
TEST
MANOMETER
G20RE
UNIT
Page 9
To Measure Flame Signal:
1 – Place meter in series between ignition control and
sensor wire. Connect the positive (+) lead of meter
to the ignition control sensor connection and the
negative (–) lead of the meter to the sensor wire.
See figure 12.
2 – Set thermostat for a heating demand and check
flame signal with unit operating. For G20RE series,
a reading of 1 to 5 microamps DC should occur.
Flame signal may rise above 1 to 5 microamps for the
first few seconds after ignition and then level off.
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.
FLAME SIGNAL TEST
FIGURE 12
IGNITION
CONTROL
“SENSE” TERMINAL
SENSOR
WIRE
D.C.
MICROAMP
METER
FLAME SENSOR
VI – BLOWER OPERATION/ADJUSTMENT
NOTE– The following is a generalized procedure
and does not apply to all thermostat controls.
A – Blower operation is dependent on thermostat con-
trol system.
1 – 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.
2 – In all cases, blower and entire unit will be off when
the system switch is in OFF position.
B – Temperature Rise
Temperature rise for G20RE units depends on unit out-
put, blower speed and static pressure of the unit setup.
Blower speed must be set for unit operation within
range of “AIR TEMP. RISE
°
F” listed on the unit rating
plate.
To Measure Temperature Rise:
1 – Place plenum thermometers in the supply and re-
turn air plenums. Locate thermometers in the first
horizontal run of the warm air plenum where it will
not pick up radiant heat from the heat exchanger.
2 – Set thermostat to highest setting.
3 – After plenum thermometers have reached their
highest 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 fir-
ing rate is acceptable, increase blower speed to re-
duce temperature. To change blower speed taps
see the Blower Speed Taps section in this manual.
C – Discharge Static Pressure
1 – Measure tap locations as shown in figure 13.
2
– Punch a 1/4” diameter
hole in supply and return
air plenums. Insert ma-
nometer hose flush with
inside edge of hole or in-
sulation. Seal around the
hose with permagum.
Connect the zero end of
the manometer to the dis-
charge (supply) side of
the system. On ducted systems, connect the other
end of manometer to the return duct as above. For
systems with non–ducted returns, leave the other
end of the manometer open to the atmosphere.
3 – With only the blower motor running and the evap-
orator coil dry, observe the manometer reading.
Adjust blower motor speed to deliver the required
amount of air.
4 – Discharge static pressure drop must not be more
than 0.5” W.C.
5 – Seal around the hole when the check is complete.
