Trane Horizon OADG Series Installation, Operation And Maintenance Manual page 56

Startup
surrounding buildings or prevailing winds cause
recirculation, a flue extension may be required to
prevent recirculation. Contact manufacturer prior
to making any flue adjustments.
• Reduced air delivery can also be the result of
inducer fan blade slippage, dirt accumulation in the
fan blade or low voltage to draft inducer motor.
Inspect draft fan assembly and be sure fan blade is
secure to motor shaft. Check line voltage to heater.
7. Flame Sensor Current Check
NOTICE
Meter Damage!
Measuring voltage with meter connect to a circuit
could result in meter damage. Do NOT measure voltage
with meter connected to a circuit.
Flame current is the current which passes through the
flame from the sensor to ground. A flame signal of 0.5
to 1.0 microamp (A) is marginal. For dependable
operation, a flame signal of greater than 1.0 A is
required. To measure flame current, connect a meter
capable of reading micro-amp current so the flame
signal will be read thru the meter's COM and A
connections. The meter should read greater than
1.0 A.
Note: If the meter reads below "0" on scale, meter
leads are reversed; disconnect power and
reconnect meter leads for proper polarity.
Figure 42. Indirect fired gas furnace components
IGNITION
CONTROLLERS
MODULATING
GAS VALVE
ROLLOUT
SWITCH
HIGH LIMIT
SWITCH
MANIFOLD GAS
PRESSURE TAP
MODULATING VALVE
INLET PRESSURE TAP
5 in. wc
56
AIR-PROVING
SWITCH
ON/OFF GAS VALVE
MINIMUM/MAXIMUM INLET PRESSURE =
7 IN. WC/14 IN. WC (1.7 KPA/3.5 KPA)
FOR NATURAL GAS AND 10 IN. WC/14 IN. WC
(2.5 KPA/3.5 KPA) FOR PROPANE
INDUCER BLOWER
INDUCER MOTOR
FLAME
FOR NATURAL GAS AND 10 IN. WC/14 IN. WC
SENSOR
ON/OFF GAS VALVE
MANIFOLD GAS
PRESSURE TAP 3.5 in. wc
CONDENSATE DRAIN
(TYP. 2)
ROLLOUT SWITCH
MINIMUM/MAXIMUM INLET PRESSURE =
7 IN. WC/14 IN. WC (1.7 KPA/3.5 KPA)
(2.5 KPA/3.5 KPA) FOR PROPANE
OAU-SVX006E-EN