Vermont Castings Pinnacle & Stardance Direct Vent - Rear Vent Gas Heaters
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 |
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1. | Spark ignitor will | A. Defective or misaligned | Using a match, light pilot. If pilot lights, turn off pilot and |
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| not light | electrode at the pilot | push the ignitor button again. If pilot will not light, check |
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| gap at electrode and pilot - it should be 1/8” to have a |
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| strong spark. |
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| B. Defective ignitor (push | Push piezo ignitor button. Check for spark at electrode |
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| button) | and pilot. If there is no spark at the pilot, and electrode |
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| wire is properly connected, replace ignitor. |
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2. | Pilot will not stay lit | A. Defective pilot generator | Check pilot flame. It must impinge on the thermocouple |
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| after carefully | (thermocouple) | or thermopile. NOTE: This pilot burner assembly uses |
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| following the |
| both a thermocouple and a thermopile. The thermo- |
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| lighting instructions |
| couple operates the pilot flame. Tighten the thermo- |
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| couple. The thermopile operates the main valve (ON and |
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| OFF). Clean and/or adjust pilot for maximum flame |
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| impingement on thermocouple and thermopile. |
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| B. Defective automatic valve | Turn valve knob to ‘Pilot’. Maintain flow to pilot; millivolt |
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| operator | meter should read greater than 10mV. If the reading is |
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| okay and the pilot does not stay on, replace the gas |
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| valve. NOTE: An interrupter block (not supplied) must be |
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| used to conduct this test. |
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| A. Remote switch or wires | Check rocker switch and wires for proper connection. |
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3. | Pilot lights, no gas | defective | Use jumper wires across terminals at rocker switch. If |
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| to burner, valve |
| burner lights, replace rocker switch. If okay, use jumper |
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| knob ON, remote |
| wires across rocker switch wires at the valve; if burner |
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| switch (rocker |
| lights, wires are faulty or connections are bad. |
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| switch) ON |
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| B. Thermopile may not gener- | 1. Be sure wire connections from thermopile at gas valve |
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| ate sufficient voltage | terminals are tight and thermopile is fully inserted into |
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| pilot bracket. |
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| 2. One of the rocker switch wires may be grounded. |
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| Remove rocker switch wires from valve terminals. If |
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| burner now stays lit, trace rocker switch wiring from |
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| ground. It may be grounded to the appliance or the |
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| gas supply line. |
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| 3. Check the thermopile with a millivolt meter. Take |
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| reading at thermopile (“TP” and “TP/TH”) terminals of | |||
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| gas valve. Should read 325 millivolts minimum while | |||
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| holding valve knob depressed in PILOT position and | |||
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| with rocker switch OFF. Replace faulty thermopile if | |||
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| reading is below specified minimum. | |||
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| C. Plugged burner orifice | Check burner orifices for debris, and remove. |
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| D. Defective automatic valve | Turn knob to ON, place rocker switch to ON, millivolt | |||
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| operator | meter should read greater than 10 mV. If the reading is | |||
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| okay and the burner does not light, replace the valve. | |||
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4. Frequent pilot | A. Pilot flame may be too low | Clean and/or adjust pilot flame for maximum flame | |||||
| outage | or high, (blowing or lifting), | impingement on thermocouple and thermopile. | ||||
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| causing the pilot to drop out |
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| B. Possible blockage of the | Check the vent terminal for blockage. | |||
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| vent terminal |
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20003457 | 31 |
