Weil-McLain EG Series 4 Pilot Won't Stay Lit

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Old 10-12-13, 08:37 AM
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Weil-McLain EG Series 4 Pilot Won't Stay Lit

Hello!

I have a 100,000 BTU Weil-McLain Series 4 (Model #: PEG-35-SPN-S) and when I went to light the pilot this season it would not stay lit.

I replaced the thermocouple and the pilot still will not remain lit.

I saw on a thread the next item to replace was the gas control valve. The unit is $179 plus shipping. It occurred to me after reading some other posts I should check to see if there power going to the control valve before replacing it.

What other trouble shooting would you suggest?

Thanks in advanced for your suggestions.
 
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Old 10-12-13, 09:15 AM
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Lou, you've looked at the pilot?

Check burner flame Pilot burner

1. Proper pilot flame (see Figure 28):
a. Blue flame.

b. Inner cone engulfing thermocouple.

c. Thermocouple glowing cherry red.
2. IMProper pilot flame:
a. Overfired Large flame lifting or blowing past thermocouple.

b. Underfired Small flame. Inner cone not engulfing thermocouple.

c. Lack of primary air Yellow flame tip.

d. Incorrectly heated thermocouple.
You're sure you are holding the pilot lighting control long enough? That thermocouple needs to be red hot before releasing the button or lever.

Do you have all manuals for the boiler?

http://www.weil-mclain.com/en/assets...sersManual.pdf

http://www.weil-mclain.com/en/assets...ler_manual.pdf

http://www.weil-mclain.com/en/assets...plement-sp.pdf

I saw on a thread the next item to replace was the gas control valve.
Don't jump to conclusions. Make sure that the thermocouple is properly installed and the pilot flame is proper as described above in the manual excerpt before doing anything further.

The control box itself has little (or nothing) to do with the pilot light not staying lit.
 
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Old 10-12-13, 12:16 PM
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Blue flame and strong but thermocouple isn't cherry red.

I am holding it down for several minutes.

I broke the pilot gas line too. All they have is 1/4".
 
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Old 10-12-13, 01:08 PM
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I broke the pilot gas line too. All they have is 1/4".
Pexsupply has both 1/8" and 1/4" aluminum pilot tubing.

I would replace the thermocouple. They don't last forever, and are inexpensive. Buy two and keep one as a spare.
 
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Old 10-12-13, 02:28 PM
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I broke the pilot gas line too. All they have is 1/4".
Who is "they" ?.......................
 
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Old 10-13-13, 06:20 PM
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I was at a plumbing supply store. I bought 2 feet of 1/4 aluminum tubing. They were out of ends so I went to ace and got 1/4 to 1/8 compression fittings and installed one end into the gas control valve and other into pilot. The gas line I broke had two small nipples at the end and screwed into the gas control valve on one end and into the pilot on the other end. The old line was likely 1/8 or 1/16 diameter. Could this not be making the flame as strong because of pressure? Flame is orange now and not hitting the thermocouple. I read that I might need to bend the thermocouple to hit flame.
 
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Old 10-13-13, 06:33 PM
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Lou, you need to replace those parts with the correct 'stuff'. One shouldn't try to cobble together a 'fix' when dealing with gas appliances. <-- 3 alarms

Could this not be making the flame as strong because of pressure? Flame is orange now and not hitting the thermocouple.
No, I don't think so, nothing to do with 'pressure'. I think it's probably leaking. Or a spiderweb in the pilot orifice.

The flame should not be orange, no matter what. Bending the thermocouple is not a solution for an orange pilot light. Fix the pilot properly and the thermocouple will be fine.

What happened between the beginning of this thread when you said the pilot flame was strong and blue, and now when you say the flame is orange?
 

Last edited by NJT; 10-13-13 at 07:02 PM.
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Old 10-13-13, 06:50 PM
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Old 10-13-13, 07:04 PM
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I believe that this is what you need:
While you're at it, order a new thermocouple of the correct length.
 
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Old 10-13-13, 07:13 PM
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I'm having a little trouble deciphering the 'thermocouple' vs 'thermopile' on these boilers.

Part manuals say that the EG=75 is the only one with a thermopile... yet when I look for the correct thermocouple, all I can find is a 'thermocouple to thermopile conversion kit' ... and it looks to be obsolete. Very strange.
 
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Old 10-16-13, 03:01 AM
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Replaced pilot gas tube and thermocouple with parts listed below.

Flame is blue at bottom with yellow/orange around thermocouple.

Pilot still goes out when I let go of red button on gas valve. What are my next steps?
 
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Old 10-16-13, 04:25 PM
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That was fast... what did you do, drive out to LI and pick the parts up?

Replaced pilot gas tube and thermocouple
You replaced the thermocouple again?

Are you using a 'universal' thermocouple?

Is the thermocouple red hot?
 
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Old 10-17-13, 03:38 AM
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UPS standard ground shipping. I was surprised it came so quick too.

It was not getting red hot with pilot. I held it down several minutes. The flame has orange in it. I cheated and used a blow torch to make it cherry red and pilot still went out when I released the red pilot button.
 
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Old 10-17-13, 03:45 AM
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I did replace thermocouple with one recommended in the margins from the pex website that was listed as a replacement for my weil mclein eg series 4. The first thermocouple was a universal one from home depot and was 24" this one os about 30".
 
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Old 10-17-13, 03:48 AM
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Pilot assembly is pretty rusty.

Will that affect intemsity of pilot?
 
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Old 10-17-13, 04:19 PM
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Pilot assembly is pretty rusty.

Will that affect intemsity of pilot?
Rusty OUTSIDE? No. But if the ORIFICE is rusty... well, maybe. If you decide to try and clean it, just clean it... do NOT do anything that will make the holes any bigger, or damage them in any way.

Have you had the pilot burner out for inspection? Did you look inside the pilot burner for spiderwebs? (seriously... you said the pilot was off all summer, correct?)

I cheated and used a blow torch to make it cherry red and pilot still went out when I released the red pilot button.
Then either there is something wrong with the thermocouple... brand new? I would tend to think not.

OR, the thermocouple is not making electrical contact into the gas valve...

OR, the system originally had a thermoPILE which has a higher output voltage than a thermoCOUPLE. (remember the weirdness I mentioned with trying to figure out if your system has a 'couple' or a 'pile' ? It just makes me wonder...)

OR, there is something wrong with the gas valve.
 
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Old 10-17-13, 04:52 PM
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Trooper gave you 3 links. Go to the third one that says plement. It has schematics, parts list and page 20 troubleshooting. Test thermocouple with meter instead of parts changing. You might have a rollout switch by your gas valve somewhere. Its a round disc with 2 wires. It should have a reset button on it. Push the reset and try lighting the pilot. That's if you have one. I wouldn't worry too much about the tube if it didn't start lit with the torch.
 

Last edited by spott; 10-17-13 at 05:45 PM.
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Old 10-19-13, 06:55 AM
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I have had the burner out and bent the pilot burner tip down a bit to try and direct it more to thermocouple. The pilot flame director get's cherry red but not thermocouple. I cleaned the pilot burner lightly with a wire brush and blew it out (no spider webs).

I am going to perform electrical checks from page 20 of the thermocouple.

Thanks for the assistance and wish me luck. I am not looking foward to calling a technician.
 
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Old 10-19-13, 04:18 PM
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I did the electrical checks and the thermopile conducts 21 ma and the manual says it should conduct 28 man. I switched meter to 200 ma to get these readings. Unit is getting electric. As NJ trouper said its seems to only be the 75 series that has a thermopile. The thermocouple was not in a package but loose in the box. Doubt it but may have something to do with it.

What do you think my next steps are?
 
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Old 10-19-13, 05:01 PM
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21ma is 75% of the 28 there looking for. I don't know what the low end would be before it wouldn't work. This i s a shot in the dark. You said at one point you used a torch. Is it possible for you you to hook up your meter again and this time use your torch and see if the reading improves. You should definitely get your 28 with that. If you don't I would say thermocouple. Did you find a rollout switch with a reset.
 
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Old 10-19-13, 05:49 PM
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Thanks for all of the suggestions!

I will try the torch but not sure that solves any problems. My next step are to install a new gas control valve, new pilot burner, and/or wiring harmess (I think in that order unless someone has a suggestion).

I wired the roll out on the door together. There is a electrical diode on it and it went in the middle of winter last year. It is a safety feature and so long as the loop is closed with or without rollout piece the furnace fires up. It Is similar to positioning powered damper open and switching power off. No reset button either way. I am replacing that once I get the pilot to stay lit and I turn the system on.
 
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Old 10-19-13, 05:52 PM
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the thermopile conducts 21 ma and the manual says it should conduct 28
Just as a 'sanity check', you should have been measuring milliVOLTS

"ma" is abbreviation for milliAMPS and of course, it's not the same thing.

If you were using milliAMP scale, then do the test again with milliVOLTS.

If your meter does not have a milliVOLT scale, then use the VOLT scale.

A reading of 0.028 Volts equals 28 milliVolts. (move decimal 3 places to the right to convert from Volts to Millivolts.)
 
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Old 10-20-13, 09:11 AM
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Checked again. Got .021 when switched to 2v. I also took gas valve off and turned foward to see if there were adjustments. Played with screws and no change. Did not try torch but I suspect pilot is either not hot enough or not registering in gas valve.

Should I order new valve and/or pilot or are more diagnostics needed?
 
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Old 10-20-13, 09:49 AM
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have you tried replacing the thermocouple?
 
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Old 10-20-13, 09:57 AM
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Replaced the thermocouple twice. One with 24" from home depot and then with weil Mclain from pexsupply.com when I ordered new pilot gas supply line and electric damper.
 
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Old 10-22-13, 07:13 PM
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Tested with a torch and meter. The old thermocouple was bad for sure. Both replacements go well over 28 milli volts with torch but not with pilot. I bent thermocouple towards pilot and it got as high as 23 milli volts. Only way I can get it to stay lit is by I bypassing switch on valve, but that defeats the purpose of saftey devise.

Any last bits of advise before I drop another $130 on new burner and gas control valve?
 
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Old 11-02-13, 10:46 AM
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All said and done after installing new gas valve I am up and running. Thank you to everyone for their advise! On the the next project!
 
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