Radiance Direct Vent /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 pilot. If pilot lights, turn off pilot and | |||
| 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 but- | Push piezo ignitor button. Check for spark at electrode | ||
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| ton) | 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 | |||
| after carefully fol- | (thermocouple) | or thermopile. NOTE: This pilot burner assembly uses | |||
| lowing the lighting |
| both a thermocouple and a thermopile. The thermocou- | |||
| instructions |
| ple operates the pilot flame. Tighten the thermocouple. | |||
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| The thermopile operates the main valve (ON and OFF). | ||
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| Clean and/or adjust pilot for maximum flame impinge- | ||
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| ment 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 | ||
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| is 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. | ||
3. | Pilot lights, no gas | defective | Use jumper wires across terminals at rocker switch. If | |||
| to burner, valve |
| burner lights, replace rocker switch. If okay, use jumper | |||
| knob ON, remote |
| wires across rocker switch wires at the valve; if burner | |||
| switch (rocker |
| lights, wires are faulty or connections are bad. | |||
| 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 read- | ||
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| ing at thermopile (“TP” and “TP/TH”) terminals of gas | ||
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| valve. Should read 325 millivolts minimum while hold- | ||
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| ing valve knob depressed in PILOT position and with | ||
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| rocker switch OFF. Replace faulty thermopile if reading | ||
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| 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 me- | ||
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| operator | ter should read greater than 10 mV. If the reading is okay | ||
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| and the burner does not light, replace the valve. | ||
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4. | Frequent pilot out- | A. Pilot flame may be too low | Clean and/or adjust pilot flame for maximum flame im- | |||
| age | or high, (blowing or lifting), | pingement 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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20004188 | 25 |
