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Old 10-07-2012, 02:28 PM   #1
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Furnace Won't Light

I'm having trouble lighting my furnace. The pilot light won't stay lit as I turn the know from "light" to "on". I have tested my thermocouple and it seems to be working. My gas valve is an Essex SX-242N. How many millivolts are required to keep the pilot light lit?? Is there any way to check the gas valve to see if it is working properly?? Thanks.


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Old 10-07-2012, 02:40 PM   #2
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Furnace Won't Light

if the thermocouple we're working the pilot would hold and stay on as you turn from PILOT to ON remove it from the top of the valve clean with rubbing alk Q-TIP then swab the opening on the valve where it screws into...if the same ned a new TC..if you have a digital meter remove the TC and put it into a burner on the stove red the end in MIllivolt setting..see if it is producing MILLI to hold valve..


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Old 10-07-2012, 03:54 PM   #3
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Furnace Won't Light

Getting a good millivolt output on a thermocouple on a stove won't tell you if its a weak or mis directed pilot plame. Look to see if the pilot flame fully envelopes the tip of the thermocouple.
If it glows hot , the pilot flame should be OK. Use at least a minute of flame time.

Those essex valves are a problem. Often the pilot solinoid will engage if after a minute of the pilot being lit and while the control knob is still being depressed, take a pair of plyers and rap on the metal base of the valve.

In the field, only checking a thermocouple while it's lit & connected to the gas valve with an adapter gives us the strength of the thermocouple/ pilot assy and whether the gas valve solinoid is strong enough with a timed and electrical lock out test..

Last edited by how; 10-07-2012 at 04:37 PM.
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