LAARS U.H.E. - Installation Manual - Manual (Page 43)

COMBUSTION SYSTEM INSPECTION
Inspect the operation of the combustion system monthly. Use the following procedure to inspect the combustion
system.
1. Turn off the main power switch of the water heater.
2. Adjust the thermostat to the Min. setting.
3. Remove the top of the combustion surround by unlatching it.
4. While observing the ignition module, turn on the main power switch.
5. Adjust thermostat to the Max. setting.
6. Watch the LED’s light as the controller goes through the S-OP as previously described.
7. Upon
ignition, observe the main burner flame.
8. Readjust thermostat to previous setting.
9. Replace combustion surround top and latch it securely in place.
SECTION XI: TROUBLESHOOTING GUIDE
Main power
light is not lit. • 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
Ignition module
"Power" LED is
not lit • Check for 120 VAC at the ignition module on "120 VAC IN." If there is voltage, then check the secondary (24 volt
terminals) voltage across the transformer as previously described. If no voltage from the secondary plug from the
transformer, replace the transformer or wire harness. If the control has 120 and 24 volt input, replace the control.
Blower does not
energize • Unplug the wire harness to the blower and check the pins for 120 volts. If no voltage, and the ignition control has 120
volts, the control may be defective, call tech support. If 120 volts is present to the blower, make sure the pins are making
good contact. Replace blower if connections are good and 120 volts is present to blower.
Ignitor does not
glow • Make sure pressure switch contacts are closed (24 volts from pressure switch harness to ground). Is there voltage to the
"Hot Surface Ignitor"? Check for 120VAC to the ignitor from the ignition module when the ignition LED is lit. If no
voltage to the ignitor, replace ignition control.
• Check the resistance value across the "Hot Surface Ignitor?" If over 120 ohms, then replace hot surface ignitor.
Main valve does
not turn on • 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 (blue) and 5 (brown) on the plug "CONTROL". If there is 24
VAC across these pins, then check to see if the "Rectifier Harness" (or gas valve harness on 100 gallon 399,999 BTU/hr
model) is secure. If it is secure, then replace the "Gas Valve".
• If you can feel the gas valve energize, check to make sure the main gas supply is not in the off position.
Burner Flame
keeps going out • 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 (4.5 min. - 14 max.).
• 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.
Thermostat does
not call for heat • 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 is 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"; If readings are not correct replace the "Potentiometer."
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