Vermont Casting 2468, 2467 manual Troubleshooting / Honeywell #8420 Gas Control System

Dutchwest Natural Vent Gas Heater

Troubleshooting / Honeywell #8420 Gas Control System

NOTE: Before troubleshooting the gas control system, be sure the external gas shutoff is in the “ON” position.

WARNING: REMOVE THE GLASS PANEL BEFORE PERFORMING ANY GAS CONTROL SERVICE WORK.

SYMPTOM		POSSIBLE CAUSES	CORRECTIVE ACTION
1.	Spark ignitor will	A. Defective or misaligned	Using a match, light [ilot. If pilot lights, turn off pilot and
	not light	electrode at the pilot	push the ignitor button again. If pilot will not light, check
			gap at electrode and pilot - it should be 1/8” to have a
			strong spark.
		B. Defective ignitor (push	Push piezo ignitor button. Check for spark at electrode
		button)	and pilot. If there is no spark at the pilot, and electrode
			wire is properly connected, replace ignitor.
2.	Pilot will not stay lit	A. Defective pilot generator	Check pilot flame. It must impinge on the thermocouple
	after carefully fol-	(thermocouple)	or thermopile. NOTE: This pilot burner assembly uses
	lowing the lighting		both a thermocouple adn a thermopile. The thermo-
	instructions		couple operates the pilot flame. Tighten the thermo-
			couple. The thermopile operates the main valve. (ON
			and OFF) Clean and/or adjust pilot for maximum flame
			impingement on thermocouple and thermopile.
		B. Defective automatic valve	Turn valve knob to “Pilot”. Maintain flow to pilot; millivolt
		operator	mete should read greater than 10mV. If the reading is
			okay and the pilot does not stay on, replace the gas
			valve. NOTE: An interrupter block (not supplied) must
			be used to conduct this test.
		C.Defective safety switch	Check the continuity accross the safety limit switch with
			the unit cold. If there is no continuity, the safety switch
			needs to be replaced.
3.	Pilot lights, no gas	A. Remote switch or wires	Check rocker switch and wires for proper connection
	to burner, valve	defective	Use jumper wires across terminals at rocker switch. If
	knob ON, remote		burner lights, replace rocker switch. If okay, use jumper
	switch (rocker		wires across rocker switch wires at the valve. If burner
	switch) ON		lights, wires are faulty or connections are bad.
		B. Thermopile may not gen-	1. Be sure wire connecitons from thermopile at gas
		ate sufficient voltage	valve terminals are tight and thermopile is fully inserted
			into pilot bracket.
			2. One of the rocker switch wires may be grounded
			Remove rocker switch wire form valve termianls. If
			burner now stays lit, trace rocker switch wiring from
			ground. It may be grounded to the appliance of the
			gas supply line.
			3. Check the thermopile with a millivolt meter. Take
			reading at thermopile (“TP” and “TP/TH”) terminals of
			gas valve. Should read 325 millivolts minimum while
			holding valve knob depressed in PILOT position and
			with rocker switch OFF. Replace faulty thermopile if
			reading is below specified minimum.
		C. Plugged burner orifice	Check burner orifices for debris, and remove.
		D. Defective automatic valve	Turn knob to ON, place rocker switch to ON. Millivolt
		operator	meter should read greater than 10mV. If the reading is
			okay and the burner does not light, replace the valve.
4.	Frequent pilot out-	A. Pilot flame may be too low	Clean and/or adjust pilot flame for maximum flame
	age	or high, (blowing or lifting).	impingement on thermocouple and thermopile.
		causing the pilot to drop out
		B. Possible blockage of the	Check the vent termianl for blockage.
		vent terminal

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