User guide

28
Table 9 - Separated Combustion Tubular Blower Troubleshooting Guide (continued)
SYMPTOMS POSSIBLE CAUSE(S) CORRECTIVE ACTION
N. Not enough heat. 1. Incorrect gas input.
2. Heater undersized.
3. Thermostat malfunction.
4. Heater cycling on limit.
5. Incorrect orifi ce sizes.
1. Refer to "Gas Input Rate"
2. Is the heater output sized correctly for the
heat loss of the space? Has the space been
enlarged? Is the heater located in the space
properly (see "Installation")?
3. Check thermostat circuit; 24V on terminals
"R" and "W" on terminal strip.
4. Check air movement across heat exchanger.
Check voltage and amps at the blower motor.
Check gas input to ensure unit is not over
fi red. Check heat exchanger to ensure unit is
not dirty.
5. Check orifi ce size (Refer to "Gas Input Rate"),
replace if necessary.
O. Too much heat. 1. Unit is over fi red.
2. Thermostat malfunction.
3. Heater runs continuously.
4. Defective gas valve.
5. Excessive gas supply pressure.
6. Excessive static pressure.
1. Refer to "Gas Input Rate." Check orifi ce size.
Replace if too large.
2. Check thermostat for operation, to ensure
circuit open and closes.
3. Check wiring per diagram. Check operation at
the gas valve. Look for a short in thermostat
circuit.
4. Replace valve and check pressure setting
(See Table 4 "Gas Piping Requirements").
5. Refer to "Pipe Installation" and Table 4 - "Gas
Piping Requirements."
6. Adjust blower sheave to correct RPM - See
"Blower Set Up and Adjustment."
P. Noisy blower/motor. 1. Blower wheel loose.
2. Blower wheel is dirty.
3. Blower wheel is rubbing on housing.
4. Bearings are dry.
5. Pulley is loose.
1. Replace or tighten.
2. Clean blower wheel.
3. Realign blower wheel.
4. Oil bearings on blower motor. (Refer to label
on motor.)
5. Check Blower and Motor pulleys. Replace or
tighten as necessary.
Q. Cold air is delivered during heater
operation.
1. Incorrect manifold pressure or input.
2. Air throughput too high.
1. Test and reset manifold pressure (see Table
4 - "Gas Piping Requirements").
2. Check Blower and Motor pulleys. Replace or
tighten as necessary.
R. High limit is tripping. 1. Unit is over fi red.
2. Air fl ow is too low.
3. Defective high limit.
4. Defective control board.
1. Refer to "Gas Input Rate." Check orifi ce size.
Replace if too large.
2. Check for proper voltage; ensure blower
assembly is correct.
3. Check operation of switch. If switch is open
during operation, check gas pressure and/
or CFM; adjust accordingly. If switch is open
during start-up, replace switch.
4. Check for 24V on line side of high limit.
Constant voltage should be recorded. If not,
control board is suspect. Check fl ash code.