Lennox International Inc O23V3-120, O23V5-140 Source Procedure, Too much heat, Too little heat

Source Procedure

Thermostat Disconnect thermostat

wires at the primary control.

•Burner turns off: ther- mostat circuit faulty.

Primary	• Burner not turning off:
control	primary control faulty.

Too much heat

Causes

Shorted or welded thermostat contacts

Stuck thermostat bimetal

Thermostat not level

Shorted thermostat wires

Thermostat out of calibration

Thermostat in cold draft

Defective primary control

Too little heat

Correction

Repair or replace the thermostat.

Clear obstruction or replace thermostat. Level thermostat.

Repair short or replace wires.

Replace thermostat.

Correct draft or relocate the thermostat. Replace the defective primary control.

Combus- tion

Check burner combustion for CO2,

stack temperature, and smoke

•Low CO2 less than 10%.

•High smoke reading more than a trace.

Too much combustion air

Air leaks into heat exchanger around inspection door, etc.

Excessive draft

Incorrect burner head adjustment

Dirty or plugged heat exchanger

Insufficient draft

Reduce combustion air.

Correct cause of air leak.

Adjust barometric draft control for correct draft. Correct burner head setting.

Clean heat exchanger.

Readjust burner.

Increase draft.

•High stack tempera- ture is more than 550F net.

Oil Pres-	Inspect fire and check
sure	oil pressure.

Incorrect burner head adjustment

Too little combustion air

Too little blower air

Dirty or plugged heat exchanger Dirty blower wheel

Dirty furnace air filters

Restricted or closed registers/dampers Partially plugged or defective nozzle Oil pressure too low: less than 100 psi.

Correct burner setting.

Increase combustion air.

Check for high static pressure.

Check HEAT selector pin per wiring diagram (figure 18, page 16).

Clean heat exchanger.

Clean blower wheel.

Clean or replace filter.

Readjust registers or dampers.

Replace nozzle.

Increase oil pressure top 100psi.

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O23V SERIES