16
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 |
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1. | Spark ignitor will not light | A. Defective ignitor | Check for spark at electrode and pilot; if no spark and electrode |
| pilot after repeated triggering | (no spark at electrode). | wire is properly connected, replace ignitor. |
| of ignitor button. |
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| B. Defective or misaligned electrode | Using a match, light pilot. If pilot lights, turn off pilot and trig- | |
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| at pilot (spark at electrode). | ger the ignitor button again. If pilot lights, an improper gas |
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| mixture caused the bad lighting and a longer purge period is |
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| recommended. If pilot will not light – check gap at electrode and |
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| pilot – should be 1/8" to have a strong spark. If gap measures |
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| 1/8", replace pilot (Figure 9 on page 8 ). |
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| C. Gas supply pressure errant. | Check inlet gas pressure. It should be within the limits as |
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| 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 (Figure |
| carefully following the light- | (thermocouple). | 9 on page 8) Clean and/or adjust pilot for maximum flame |
| ing instructions. |
| impingement on thermocouple. Ensure that the connection |
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| between the valve and thermocouple are tight and secure. |
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3. | Pilot burning, no gas to | A. Wall switch or wires defective. | Check wall switch and wires for proper connections. Jumper |
| burner, Valve knob “ON,” |
| wire across terminals at wall switch, if burner comes on, re- |
| Wall Switch “ON.” |
| place defective wall switch. If okay, jumper wires across wall |
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| switch wires at valve, if burner comes on, wires are faulty or |
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| connections are bad. |
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| B. Thermopile may not be generating | Check thermopile with millivolt meter. Take reading at thermo- |
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| sufficient millivoltage. | pile terminals of gas valve. Should read 325 millivolts minimum |
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| with optional wall 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 orifice for stoppage and remove. |
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4. | Frequent pilot/burner outage | A. Pilot flame may be too low or | Clean and/or adjust pilot flame for maximum flame impinge- |
| problem. | blowing (high) causing the pilot/ | ment on thermocouple (Figure 9 on page 8 ). |
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| valve safety to drop out. |
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