Problem with Weil-McLain Boilers -- related?

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Old 03-14-18, 04:48 PM
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Problem with Weil-McLain Boilers -- related?

We have a duplex with two different Weil-McLain CG boilers, one for each floor.

The Philadelphia Gas Works came out and replaced both meters for the duplex back in June '17. When the PGW worker turned the gas back on, he had a hard time relighting the pilot for the 1st floor boiler. He had to play with it for about 20 minutes, and kept tapping the line, which fluctuated the size of the pilot. He commented that it was probably about time for a new thermocouple, but he finally got it working.

The first floor is vacant, so the heat it set way down anyway. I have no way of knowing if the pilot was lit all winter.

Then the Nor'easter hit us two weeks ago, and I noticed it started to get cold on the 2nd floor. I went and checked and BOTH pilots were out on both boilers. I assumed that either: a) the gas went out for a time, or b) a strong draft must have blown them out. I was able to light the 2nd floor, but was unable to get the 1st floor lit. With the help of YouTube, I was able to replace the thermocouple on my own a few days later.

However, to my dismay, when I went to check on things a half hour later, I noticed the 2nd floor boiler was not running. The pilot was out again. I re-lit the pilot, and noticed it took a very long time to get the temperature up to 180F, but it eventually did.

Well, the pilot burned out again a few days ago, and this time I replaced the thermocouple on the 2nd floor boiler as well. Since I found it unlikely that I'm having similar problems with two different boilers. When I did it, I vacuumed out all the ductwork to make sure nothing was blocking the exhaust which might cause the gas supply to get shut off.

So as of right now, the 2F boiler's been running for almost three hours, and the temperature of the water in the boiler is only 90F. The burner flames are burning, but are low, and mostly blue. And here's the best part -- when I try to light the pilot on the 1F boiler, the pilot is so low it won't heat up the thermocouple.

I'd like some thoughts on this before I call a pro in, but I'm beginning to think there may be a problem with the pressure in the gas lines, since obviously this is affecting both boilers.

Thanks in advance!
 
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Old 03-14-18, 05:09 PM
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First off..... the thermocouple has nothing to do with the size of the flame. It's a safety device that requires the heat of the pilot to keep the pilot valve open.

If these boilers were ok before the meters were replaced..... and my guess is they were..... get the gas company back to measure actual operating pressure at the boilers. Since both boilers are suffering from the same problem.... it's pointing to a gas supply issue. Possibly a regulator issue at the meters.

Does anything else require gas in the house ? Is it ok ?
 
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Old 03-14-18, 05:20 PM
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C,
It does sound like gas problems to me. With 2 With 2 problematic boiler you have your gas supply is your common denominator.

Your thermocouple only comes in to play once the pilot is lit. It's job is to send a signal to the gas valve that it's OK to open.

If your pilot will not lite because of low flame your t-couple has nothing to do with it.

You should have about 3.5"WC to your burner, have someone or you check with gauge.

There is an adjustment screw on the gas valve but I wouldn't fool with it since both burners are doing the same thing.

Check your main gas first. After gas meters were installed was gas cocks opened up all the way.
 
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Old 03-14-18, 05:32 PM
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Thanks for the responses.

I must admit, I think the 1F thermocouple really was bad, because we both struggled to light that pilot, but after I replaced it, it lit right up.

I think the problem is that when one boiler is running, the pressure drops enough that the other pilot burns out. That's why right now (while the 2F boiler is running) I can't light the 1F pilot. I could test my theory by shutting down the 2F boiler and try to light the 1F, but I don't want to mess with it

spott, all the gas cocks are totally perpendicular with the supply lines, so i'm going to assume they're fine.
 
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Old 03-14-18, 05:37 PM
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It sounds like the valves are all on. There's a good chance they changed/replaced the regulator and that is causing the issue.

Checking the gas pressures is a service the gas company is obligated to perform.... no charge.
 
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Old 03-14-18, 05:49 PM
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You also have cocks at the meters and a main line **** on the street that he probably had to shut off to change the meters. Sounds like a pressure problem from the meters which as PJ mentioned is the gas co. responsibility.
 

Last edited by spott; 03-14-18 at 06:05 PM.
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Old 03-14-18, 06:16 PM
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Originally Posted by spott View Post
You also have cocks at the meters and a main line **** on the street that he probably had to shut off to change the meters. Sounds like a pressure problem from the meters which as PJ mentioned is the gas co. responsibility.
spott, Yeah, that's what I meant. The two cocks at the meters and the shutoffs at each boiler are all parallel (I said perpendicular, but that would actually be "off", lol)

UPDATE: My wife was running the oven, half to heat the place and half to make dinner. Once the oven got shut off, I checked and suddenly the temp of the water has increased so much I can barely touch the pipe. Sounds like our theory holds water.
 
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Old 03-14-18, 08:26 PM
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Another Update:

Thermostat set to 68. Still only 66. baseboard heat warm, not hot, so apparently the temperature of the boiler dropped again.

Is it possible the gas pressure could be fluctuating?
 
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