Lennox International Inc. o23v - Manual (Page 29)

Page 29
Troubleshooting: Burner starts and fires, but short cycles (too little heat)
Source Procedure Causes Correction
Thermostat Check thermostat. Heat anticipator set too low Correct heat anticipator setting.
Vibration at thermostat Correct source of vibration.
Thermostat in the path of a warm air
draft Shield thermostat from draft or relocate.
Limit Control Connect voltmeter between
line voltage connections to Dirty furnace air filters Clean or replace filter.
line voltage connections to
primary control (black &
white leads). If burner
Burner running too slow Increase blower speed to maintain proper
temp. rise.
white leads). If burner
cycles due to power
interruption it is cycling on
Blower motor seized or burned out Replace motor.
interruption, it is cycling on
limit.
Blower bearings seized Replace bearings and shaft.
limit.
Blower wheel dirty Clean blower wheel.
Blower wheel in backward Reverse blower wheel.
Wrong motor rotation Replace with properly rotating wheel.
Restrictions in return or supply air
system Correct cause of restriction.
Adjustable limit control set too low Reset limit to maximum stop setting.
Power If voltage fluctuates, fault is
in the power source. Loose wiring connection Locate and secure connection.
in the power source.
Recheck voltage at the
power source.
Low or fluctuating line voltage Call power company.
Troubleshooting: Burner starts and fires, but loses flame and lock out on safety
Source Procedure Causes Correction
Poor Fire After burner fires,
immediately jumper Unbalanced fire Replace nozzle
immediately jumper
across flame detector
terminals at the primary
Too much air − − lean short fire Reduce combustion air − check combustion.
terminals at the primary
control.
S
If burner continues to
Too little air − − long dirty fire Increase combustion air − check combustion.
S
If burner continues to
run (does not lock out
of safety) fault may be
Excessive draft Adjust barometric damper for correct draft.
of safety), fault may be
poor fire. Inspect fire.
Too little draft or restriction Correct draft or remove restriction.
Flame Detector
S
If fire is good, check for Dirty CAD cell face Clean CAD cell face. g ,
fault in flame detector
circuit.
Faulty CAD cell − − exceeds 15000
hms Replace CAD cell.
Loose or defective cad cell wires Secure connections or replace cad cell holder
and wire leads.
Pump loses prime − air slug Prime pump at bleed port
Oil Supply
S
If burner loses flame
(does not lock out on Pump loses prime − air leak in
supply line Check supply line for loose connections and
tighten fittings.
(does not lock out on
safety), fault is in the
fuel system.
Water slug in line Check oil tank for water (over 1 inch) pump or
drain out water.
Partially plugged nozzle or nozzle
strainer Replace nozzle.
Listen for pump whine Restriction in oil line Clear restriction.
Plugged fuel pump strainer Clean strainer or replace pump.
Cold oil − outdoor tank Change to number 1 oil.