Lennox International Inc. o23v - Manual (Page 30)

Page 30
Troubleshooting: Burner runs continuously (too much or too little heat)
Too much heat
Source Procedure Causes Correction
Thermostat Disconnect thermostat
wires at the primary Shorted or welded thermostat contacts Repair or replace the thermostat.
wires at the primary
control.
Stuck thermostat bimetal Clear obstruction or replace thermostat.
control.
S
Burner turns off: ther-
Thermostat not level Level thermostat.
Burner turns off: ther
mostat circuit faulty.
Shorted thermostat wires Repair short or replace wires.
Thermostat out of calibration Replace thermostat.
Thermostat in cold draft Correct draft or relocate the thermostat.
Primary
control
S
Burner not turning off:
primary control faulty. Defective primary control Replace the defective primary control.
Too little heat
Combus-
tion Check burner
combustion for CO2 Too much combustion air Reduce combustion air.
tion combustion for CO2,
stack temperature, and
smoke
Air leaks into heat exchanger around
inspection door, etc. Correct cause of air leak.
smoke
S
Low CO
2
less than
Excessive draft Adjust barometric draft control for correct draft.
Low CO
2
less than
10%. Incorrect burner head adjustment Correct burner head setting.
S
High smoke reading
more than a trace. Dirty or plugged heat exchanger Clean heat exchanger.
Readjust burner.
Insufficient draft Increase draft.
Incorrect burner head adjustment Correct burner setting.
Too little combustion air Increase combustion air.
S
High stack tempera-
ture is more than Too little blower air Increase blower speed to maintain proper
temperature rise.
ture is more than
550
_ F Net. Blower belt too loose (if equipped) Tighten blower belt.
Dirty or plugged heat exchanger Clean heat exchanger.
Dirty blower wheel Clean blower wheel.
Dirty furnace air filters Clean or replace filter.
Restricted or closed registers/dampers Readjust registers or dampers.
Oil Pres-
sure Inspect fire and check
oil pressure Partially plugged or defective nozzle Replace nozzle.
sure oil pressure.
Oil pressure too low: See table 6. Increase oil pressure. See table 6.