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18-CD19D6-32 37
Installer’s Guide
BURNER BOX TEMPERATURE LIMIT DEVICE
All models are equipped with a manual reset tempera-
ture limit located on the burner box. In case of exces-
sive temperature, the limit will open and cause the cir-
cuit to open which shuts off all flow of gas.
ABNORMAL CONDITIONS
1. EXCESSIVE COMBUSTION PRESSURE (WIND IN
EXCESS OF 40 M.P.H.) VENT OR FLUE BLOCK-
AGE
If pressure against induced draft blower outlet be-
comes excessive, the pressure switch will open and
shut off the gas valve until acceptable combustion
pressure is again available.
2. LOSS OF FLAME
If loss of flame occurs during a heating cycle, or
flame is not present at the sensor, the flame control
module will close the gas valve. The flame control
module will then recycle the ignition sequence,
then if ignition is not achieved, it will shut off the
gas valve and lock out the system.
3. POWER FAILURE
If there is a power failure during a heating cycle,
the system will restart the ignition sequence auto-
matically when power is restored if the thermostat
still calls for heat.
4. GAS SUPPLY FAILURE
If loss of flame occurs during a heating cycle, the
system integrated control module will recycle the
ignition sequence, then if ignition is not achieved,
the integrated control module will shut off the gas
valve and lock out the system.
5. INDUCED DRAFT BLOWER FAILURE
If pressure is not sensed by the pressure switch, the
contacts will remain open and not allow the gas
valve to open, therefore the unit will not start. If
failure occurs during a running cycle, the pressure
switch contacts will open and the gas valve will
close to shut the unit down.
6. CONDENSATE DRAIN BLOCKAGE
If the condensate drain is blocked, either by debris,
improper draining, or by freezing condensate, the
pressure switch will sense the accumulation of con-
densate in the furnace drain pan. The pressure
switch contacts will open and remain open, not al-
lowing unit operation. The unit will not operate un-
til the condensate drain has been cleared, and the
condensate flows freely.
7. RESET AFTER LOCKOUT
When the integrated control module has shut the
system down and gone into lockout, the system
must be manually reset before the unit will restart.
To reset, turn the system power off, then on, then
off and then on again within 30 seconds. This may
be done at the unit’s power source or at the ther-
mostat. The system will not reset unless the proce-
dure off-on-off-on is completed within 30 seconds.
8. RESET AFTER BURNER BOX LIMIT SHUT-
DOWN
If the furnace shuts down, one thing that can be
checked is the burner box temperature limit switch.
It is located on the bottom of the burner box. The
vent and combustion air inlet terminations should
be checked for blockage. If blockage exists, clear
the problem and then the reset button may be de-
pressed. If there is no blockage of the termina-
tions, the limit switch must be reset by a
qualified servicer.
Carbon monoxide, fire or smoke can cause serious
bodily injury, death, and/or property damage.
A variety of potential sources of carbon monoxide can be
found in a building or dwelling such as gas-fired clothes
dryers, gas cooking stoves, water heaters, furnaces and
fireplaces. The U.S. Consumer Product Safety Commis-
sion recommends that users of gas-burning appliances
install carbon monoxide detectors as well as fire and
smoke detectors per the manufacturers installation in-
structions to help alert dwelling occupants of the pres-
ence of fire, smoke or unsafe levels of carbon monoxide.
These devises should be listed by Underwriters Labo-
ratories, Inc. Standards for Single and Multiple Station
Carbon Monoxide Alarms, UL 2034 or CSA Interna-
tional Standard, Residential Carbon Monoxide Alarming
Devices, CSA 6.19
NOTE:
The manufacturer of your furnace does not test any de-
tectors and makes no representations regarding any
brand or type of detector.