SEQUENCE OF OPERATION
1-Flip toggle switch to either manual or thermostat position.
2-Red LED light on ignition controller will come on for 1 second
3-Burner fan motor will start, unit will pre-purge for 45 seconds
4-Spark ignitor energized for 4 seconds, gas solenoid valves will open during 4 second TFI ( trial for
ignition)The unit has three trials for ignition before lockout.
5-Burner lights, ignitor stops and flame current is sensed by ignition controller.
6-When heat exchanger reaches certain temperature ( temperature setting on fan switch) the fan switch will
make and start supply fan.
7-When unit is shut off, burner will shut down and supply fan will run until heat exchanger temperature is
below fan switch set point.
LP/NG TROUBLE SHOOTING GUIDE
*ALWAYS CHECK FOR SUFFICIENT POWER, GAUGE CORD, POLARITY AND GAS
PRESSURE .POWER AND GAS SUPPLY MUST ALWAYS BE SHUT OFF/DISCONNECTED
BEFORE REMOVING OR REPLACING ANY COMPONENTS ON THE HEATER*
1-UNIT WILL NOT START
A- Check for 115 volts AC across terminals 1 and 2. I f no voltage check power source.
B- Check for power across terminals 2 and 3. If no power, inspect toggle switch or thermostat,
replace if faulty
C- Check the thermal overloads on burner supply fan motor. Reset by pushing the red button on
motor housing.
D- Ensure proper connection to burner fan. If power is at connection, and neutral wire secure,
replace burner motor.
2-RED LED LIGHT DOES NOT FLASH ON START UP
A- Check for power across terminals 2 and 4. If no power remove high limit cover and check for
power on high limit. If no power there inspect air switch and tubing. Adjust and/or replace as necessary. I f
high limit powered on one side only, replace high limit.
B- Check power at 2 amp fuse. Replace if faulty.
C- Check across 120v side of transformer for power. On 24v side, should be 24v. I f not replace
transformer.
D- Check across 5 amp fuse for power. Replace if faulty.
E- Check L1 connection to terminal 4, ensure good connection.
F- Ensure proper ground at gas primary.
G- Bad controller, check LED for steady on or flashing codes.
H-If LED light stays on during pre-purge cycle, replace ignition controller.
3-BURNER WILL NOT IGNITE.
A- Always make sure gas supply pressure is 14” (½ lb) or less as over that amount could cause
damage to manifold regulator.
B Check gas pressure at 1/8” tap on elbow of manifold. Ensure pressure is correct
(1.8” for IDH350 and 3.0” for IDH500). If no pressure there, remove cover and check f or 24v across solenoid
valve wires. If voltage present, replace solenoid valve.
C- If no voltage, at solenoid valve, check gas primary control to ensure wired and grounded
properly. If wired properly, and still no voltage to solenoid replace gas primary.
D- Remove the electrode assembly form burner housing. Shut off all manual gas valves then reset
the unit. Install jumper wire between terminals 3 and 4. Lay electrode assembly across top of burner
housing. Carefully check for spark across the ignition gap after 34 second pre-purge. If no spark, check for
120VAC at ignition transformer. If power there, replace transformer, no power, replace gas primary. I f spark
is arcing at another point other tan tip of spark rod, ensure spark rod is in correct position. If it is then replace
spark rod. After test remove jumper from terminals 3 and 4.
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Summary of Contents for IDH350QR LP/NG
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