31
SYMPTOMS
POSSIBLE CAUSE(S)
CORRECTIVE ACTION
1. Open all manual valves, check for
leaks. Inspect all gas piping and repair
accordingly.
2. Turn on power supply, check fuses
and replace if bad.
3. Turn up thermostat. Check for 24V on
terminals R and W1 on terminal strip.
4. Check switch for continuity if open
with no heat present; replace.
5. Check switch operation to ensure
switch closes after power vent purge
period. If it does not make, check
tubing connections for blockage.
6. Check for continuity and voltage in
safety and control circuits; replace
an item where continuity or voltage
not
found.
7. Check all wiring per diagram.
8. Check all ground wires and
connections.
9. Check both for wiring according to
diagram.
1. Refer to “Venting” section of this
manual.
2. Check gas supply pressures to the unit.
Refer to “Gas Supply Pressure” Table
in the Pipe Installation section of this
manual.
3. A minimum of 50°F (10°C) thermostat
setting must be maintained to deter
formation of condensation. See
“Installation” section of this manual.
1. Relocate thermostat away from
outside wall or drafts.
2. Check thermostat circuit for open
and close on heater terminal strip
“R”
and
“W.”
3. Check thermostat circuit for shorts or
any staples piercing wires.
4. If thermostat is calling after set point
has been satisfi ed, replace.
5. Check for 24V on gas valve terminals
when thermostat not calling. Replace
if
necessary.
6. Check for 24V at terminals “R”
and “W.” If not present and board is
not in fl ash code mode, replace board.
7. Refer to “Gas Supply Pressure” Table
in the Pipe Installation section of this
manual.
G. Failure to ignite.
H. Condensation.
I. Burners will not shut off.
1. Gas
leak.
Shut off gas supply
immediately!
2. No power supply to the unit.
3. Thermostat not calling.
4. Defective high limit switch.
5. Defective air pressure switch.
6. Defective spark ignitor, gas valve,
thermostat or transformer.
7. Loose
wiring.
8. Improper
ground.
9. Improper thermostat or transformer
wiring.
1. Improper
venting.
2. Unit under fi red.
3. Building/space too cold.
1. Thermostat located improperly.
2. Improper thermostat wiring.
3. Shorted
circuit.
4. Defective
thermostat.
5. Defective/sticking gas valve.
6. Defective control board.
7. Excessive gas supply pressure.
Table 8A – Tubular Duct Furnace Troubleshooting Guide (continued)
