Lennox OHR23-105 - Page 24

Page 24
Troubleshooting: Burner runs continuously (too much heat).
Source Procedure Check Causes Correction
Thermostat Check Burner; if burner
turns off, fault is in the
th t t i it
Shorted or welded
thermostat contacts
Repair or replace the
thermostat.
thermostat circuit.
Stuck thermostat bimetal Clear obstruction or replace
thermostat.
Di
sco
nn
ect
Thermostat not level Level thermostat.
Disconnect
thermostat
itth
Shorted thermostat wires Repair short or replace wires.
wires at the
primary
control
Thermostat out of
calibration
Replace thermostat.
control
.
Thermostat in cold draft Correct draft or relocate the
thermostat.
Primary
control
Check Burner: if burner
does not turn off, fault is
in the primary control.
Defective primary control Replace the defective primary
control.
Troubleshooting: Burner runs continuously (too little heat).
Source Procedure Causes Correction
Combustion Check burner
comb stion
Too much combustion air Reduce combustion air.
combustion
for CO
2 −
Low
CO
2
if less
Air leaks into heat exchanger
around inspection door, etc.
Correct cause of air leak.
CO
2
if
less
than 10%.
Excessive draft Adjust barometric draft control for correct draft.
Incorrect burner head adjustment Correct burner head setting.
Check burner
comb stion
Dirty or plugged heat exchanger Clean heat exchanger.
combustion
f
o
r
s
m
o
k
e
−
Readjust burner.
for
smoke
−
High smoke
di
Insufficient draft Increase draft.
g
reading more
than a trace.
Incorrect burner head adjustment Correct burner setting.
than
a
trace
.
Too little combustion air Increase combustion air.
Check burner
combustion
tk
Too little blower air Increase blower speed to maintain proper
temp. rise.
stack
temperature
−
Blower belt too loose (if equipped) Tighten blower belt.
temperature
−
High stack
tt
Dirty or plugged heat exchanger Clean heat exchanger.
g
temperature
is more than
Dirty blower wheel Clean blower wheel.
is
more
than
550F Net.
Dirty furnace air filters Clean or replace filter.
Restricted or closed registers or
dampers
Readjust registers or dampers.
Oil Pressure Inspect fire
and check oil
Partially plugged or defective
nozzle
Replace nozzle.
pressure.
Oil pressure is too low: less than
100 psi.
Increase oil pressure top 100psi.