17
Troubleshooting Guide
READ THIS ENTIRE SECTION BEFORE
BEGINNING TO TROUBLESHOOT PROBLEMS.
The following troubleshooting flow charts provide systematic
procedures for isolating equipment problems.
DO NOT SERVICE THESE HEATERS UNLESS YOU ARE AN
AUTHORIZED GAS HEATER SERVICE PERSON..
TEST EQUIPMENT REQUIRED
The following pieces of test equipment will be required to
troubleshoot this system.
• Digital Multimeter
- for measuring AC and DC voltage and
resistance.
• Low Pressure Gauge
- for checking inlet and outlet
pressures of the gas control valve against dataplate rating.
INITIAL PREPARATION
■
Visually inspect equipment for apparent damage.
■
Check all wiring for loose connections and worn
insulation.
Refer to the system operation sequence in this section to
understand how the heater operates during a call for heat.
If the heater is not operational, push and release the reset
switch to restart the heater. Observe heater operation.
Identify the problem and refer to the appropriate
troubleshooting flow charts for problem solving. Perform all
troubleshooting steps identified by the flow charts.
Problems
Page
Fan motor does not run, heater does not light. . . . . . . . . .18
Fan motor runs, igniter does not spark. . . . . . . . . . . . . . . .19
Fan motor runs, igniter sparks,
but heater does not light . . . . . . . . . . . . . . . . . . . . . . . . . .20
Heater lights, but does not stay lit . . . . . . . . . . . . . . . . . .21
Components should be replaced only after each step within
the flow chart has been completed and replacement is
suggested in the flow chart. Refer to the Servicing sections
as necessary to obtain information on disassembly and
replacement procedures of the component. Verify proper
heater operation after servicing.
DIRECT IGNITION OPERATION SEQUENCE:
— Line voltage is supplied to motor relay, ignition control
and thermostat.
— A call for heat occurs from the thermostat.
— Thermostat contacts close.
— Ignition control performs self safety check
-- Internal components are tested
-- Air proving circuit is checked
— Ignition control sends line voltage to motor relay.
-- Relay contacts close
-- Relay sends power to fan motor
-- Fan motor starts
— Ignition control sends line voltage to air proving switch.
-- Air proving switch contacts close on an increase in
air pressure.
— Ignition control begins ignition trial sequence.
— Ignition control sends line voltage to transformer.
— Transformer reduces line voltage to 24 volts.
-- 24 volts is sent to fuse.
-- Fuse sends 24 volts to high limit switches.
-- High limits send 24 volts to gas control valve.
-- Gas control valve opens.
— Ignition control sends high voltage to igniter electrode.
-- Igniter sparks.
-- Ignition occurs.
— Igniter continues to spark until flame proving occurs.
-- Ignition spark is shut off.
-- Gas control valve stays open.
— Room warms to desired temperature.
-- Thermostat is satisfied, thermostat contacts open.
-- Heater shuts down.
— Process begins again on a call for heat.
IGNITION FAILURE SEQUENCE
— There are three trials for ignition. Each trial for ignition
takes approximately 15 seconds
— If ignition is not maintained, the ignition control shuts
the heater down.
-- Gas valve closes
-- Ignition spark is discontinued
-- Fan motor stops
— The ignition control must be reset to restart the heater.
--- Push and hold the reset switch until fan motor
restarts.
WARNING
Electrical Shock and Burn Hazard
■
Troubleshooting this system may require operating the
unit with line voltage present and gas on. Use extreme
caution when working on the heater.
■
Failure to follow this warning may result in property
damage, personal injury, or death.
