Hearth and Home Technologies CD4842MLR, CD4842MR Troubleshooting, Standing Pilot Ignition System

15 Troubleshooting

With proper installation, operation, and maintenance your gas appliance will provide years of trouble-free service. If you do experience a problem, this troubleshooting guide will assist a qualified service technician in the diagnosis of a problem and the corrective action to be taken. This troubleshooting guide can only be used by a qualified service technician. Con- tact your dealer to arrange a service call by a qualified service technician.

A. Standing Pilot Ignition System

Symptom	Possible Causes	Corrective Action
1. After repeated triggering	A. No gas or low gas pressure.	Check the remote shut-off valves from the appliance. Usually, there
of the red or black piezo		is a valve near the gas main. There can be more than one valve
ignitor button, the spark		between the appliance and the main.
ignitor will not light the	B. No lp in tank.	Check the LP (propane) tank. You may be out of fuel.
pilot. Check for spark.
	C. Ignitor.	Check the spark at the electrode and pilot. If no spark and electrode
		wire is properly connected, replace the ignitor. Verify that there is
		no short in electrode wire.
	D. Pilot or misaligned electrode	Using match, light the pilot. If the pilot lights, turn off the pilot and
	(spark at electrode).	trigger the piezo ignitor button again. If the pilot lights, an improper
		gas/air mixture caused the bad lighting and a longer purge period
		is recommended. If the pilot will not light, ensure the gap at the
		electrode and pilot is one-eighth inch to have a strong spark. If the
		gap is OK, replace the pilot.
2. The pilot will not stay lit	A. Thermocouple.	Check that the pilot flame impinges on the thermocouple. Adjust the
after carefully following the		pilot for proper flame impingement.
lighting instructions.
		Ensure that the thermocouple connection at the gas valve is fully
		inserted and tight (hand tighten plus 1/4 turn).
		Verify proper voltage output from the thermocouple to the valve.
		Place one millivolt meter lead wire on the thermocouple copper
		lead. Place the second lead wire on the solder button on the back
		of the valve (blue wire). Start the pilot and hold the valve knob in.
		The millivolt reading should read 8-16 millivolts. If millivolt reading
		is less than 8 millivolts, replace thermocouple.
	B. Improper gas inlet pressure.	Natural gas should be 5-14 in. w.c. LP should be 10-14 in. w.c.
		Verify pressure with manometer.
	C. Control valve.	If the thermocouple is producing 8-16 millivolts, replace control
		valve.
3. The pilot is burning, there	A. On/off switch or wires	Check the ON/OFF switch and wires for proper connections. Place
is no burner flame, the	defective.	the jumper wires across the terminals at the switch. If the burner
valve knob is in the ON		comes on, replace the defective switch. If the switch is OK, place
position, and the ON/OFF		the jumper wires across the switch wires at the gas valve. If the
switch is in the ON		burner comes on, the wires are faulty or connections are bad.
position.
	B. Thermopile may not be	Check that the pilot flame impinges thermopile properly.
	generating sufficient	Be sure the wire connections from the thermopile at the gas valve
	millivoltage.
		terminals are tight and that the thermopile is fully inserted into the
		pilot bracket.
		Check the thermopile with a millivolt meter. Take the reading at
		TH-TP&TP terminals of the gas valve. The meter should read 350
		millivolts minimum, while holding the valve knob depressed in the
		pilot position, with the pilot lit, and the ON/OFF switch in the OFF
		position. Replace the thermopile if the reading is below the specified
		minimum.
		With the pilot in the ON position, disconnect the thermopile leads
		from the valve. Take a reading at the thermopile leads. The reading
		should be 350 millivolts minimum. Replace the thermopile if the
		reading is below the minimum.

58 Heatilator • Caliber Mesh CD Series-SIT Valve • 4040-849 Rev J • 06/08