TROUBLESHOOTING THE MILLIVOLT GAS CONTROL SYSTEM
Note: Before troubleshooting the gas control system, be sure external gas shut off valve (located at gas supply inlet) is in the “ON” position.
Important: Valve system troubleshooting should only be accomplished by a qualified service technician.
| SYMPTOM | POSSIBLE CAUSES | CORRECTIVE ACTION |
1. | Spark igniter will not light pilot after | A. Defective igniter | Check the gap between the electrode and pilot. It should |
| repeated triggering of igniter button. | (no spark at electrode). | be between 1/8” and 3/16." If the gap is out of this |
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| range, adjust the gap or replace the pilot. |
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| B. Defective or misaligned electrode at pilot | Using a match, light pilot. If pilot lights, turn off pilot |
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| (spark at electrode). | and trigger the igniter button again. If pilot lights, an |
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| improper gas mixture caused the bad lighting and a |
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| longer purge period is recommended. If pilot will not |
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| light – check gap at electrode and pilot – It should |
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| be between 1/8” and 3/16." If the gap is out of this |
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| range, adjust the gap or replace the pilot. (Figure 18 |
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| on page 9 ). |
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| C. Gas supply pressure errant. | Check inlet gas pressure. It should be within the limits |
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| as marked on the rating plate. |
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| D. Pilot orifice plugged. | Clean or replace pilot orifice. |
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2. | Pilot will not stay lit after | A. Defective pilot generator | Check pilot flame, it must impinge on thermocouple |
| carefully following the lighting | (thermocouple). | (Figure 18 on page 9 ). Clean and/or adjust pilot for |
| instructions. |
| maximum flame impingement on thermocouple. |
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| Ensure that the connection between the valve and |
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| thermocouple are tight and secure. |
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3. | Pilot burning, no gas to burner, Valve | A. Wall switch or wires defective. | Check wall switch and wires for proper connections. |
| knob “ON,” Wall Switch “ON.” |
| Jumper wire across terminals at wall switch, if burner |
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| comes on, replace defective wall switch. If okay, jumper |
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| wires across wall switch wires at valve, if burner comes |
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| on, wires are faulty or connections are bad. |
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| B. Thermopile may not be generating suf- | Check thermopile with millivolt meter. Take reading |
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| ficient millivoltage. | at thermopile terminals of gas valve. Should read |
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| 325 millivolts minimum with optional wall switch |
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| “OFF.” Replace faulty thermopile if reading is below |
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| specified minimum. |
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| C. Plugged burner orifice. | Check burner orifice for stoppage and remove. |
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4. | Frequent pilot/burner outage prob- | A. Pilot flame may be too low or blowing (high) | Clean and/or adjust pilot flame for maximum flame |
| lem. | causing the pilot/valve safety to drop out. | impingement on thermocouple (Figure 18 on page |
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| 9 ). |
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NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE. | 15 |
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