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TNR-I&S-02
Make sure that water heater is plugged in.
When the switch is on, is there 120VAC between L1 and N on the terminal block? If not, then
check for loose wire connections on the “Power Switch Wire Harness.” If connections are ok, then
replace the switch.
If there is voltage between L1 and N then the light on the switch is burnt out. Replace switch.
Make sure that the temperature of the tank is cool.
If the thermostat does not call for heat, then check the PRIMARY voltage across the “Transformer”.
If there is voltage across the PRIMARY, then check the voltage across the SECONDARY leads of
the “Transformer”.
Install a jumper wire from N.O. terminal to the COM terminal on the “Thermostat PC Board.” If
the thermostat calls for heat after installing a jumper wire then check the “Thermostat Sensor
Probe” leads for proper resistance with an OHM meter (See appendix A).
If sensor reading are not correct, replace “Thermostat Sensor Probe.”
If the sensor readings are correct, then check “Potentiometer” for the proper resistance. If the
readings are correct, then replace the “Thermostat PC Board”, otherwise replace the
“Potentiometer.”
Check for 120 VAC at the ignition module on “120 VAC IN.” If there is voltage, then replace the
ignition module.
If there is not any voltage, check the voltage across the transformer as previously described.
Is the “Vacuum Switch” (air intake switch) N.C.? If no, then check the hose and see if it is filled
with condensate. If the hose is not filled with condensate, then replace vacuum switch. If filled,
empty hose.
Is the “Pressure Switch” (exhaust pressure switch) N.O.? If no, then check the hose and see if it
is filled with condensate. If the hose is not filled with condensate, then replace pressure switch.
If filled empty hose.
Is the “Collector Limit Switch” N.C.? If no, then reset switch. If this switch trips more than 3
times, call service.
If all items above are ok, then replace the blower.
Is there voltage to the “Hot Surface Ignitor”? Check for 120VAC to the ignitor from the ignition
module.
Is there continuity across the “Hot Surface Ignitor?” If no, then replace hot surface ignitor. If
yes, then replace the ignition module.
Put your hand on the gas valve. When the “Valve” LED lights on the ignition module, can you
feel it energize? If not, then check the voltages at the ignition module across pins 2 and 7 on
the plug “CONTROL”. If there is 24 VAC across these pins, then check to see if the “Rectifier
Harness” is secure. If it is secure, then replace the “Gas Valve”.
If you can feel the gas valve energize, check the main gas supply is not in the off position.
Is there minimum gas supplied to water heater as stated on the rating plate? If not, then
increase the supply pressure to the water heater.
Measure the microAmps through the flame sensor using a multimeter. Is there at least 4
microAmps? If not, then replace the “Flame Sensor” or flame sensor wire.
Is the tank temperature above the temperature set point?
Does the T&P relief valve leak? If yes, then replace “Thermostat PC Board.”
Check “Vacuum Switch” (air intake switch) as previously mentioned.
Check “Pressure Switch” (exhaust pressure switch) as previously mentioned.
Check “Collector Limit Switch” as previously mentioned.
If above switches are all ok, then replace “Ignition Module.”
TROUBLESHOOTING GUIDE
Main power light is not lit.
Thermostat does not call for heat.
Ignition module “Power” LED is not lit.
Blower does not energize.
Ignitor does not glow.
Main valve does not turn on.
Burner Flame keeps going out.
Thermostat does not satisfy.
Blower did not post purge
9/07
Printed in USA
