Weil McLain CG-4 boiler roll out switch blowing

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Weil McLain CG-4 boiler roll out switch blowing

Postby caryalon » Wed Feb 22, 2012 7:39 pm

I have a Weil McLain CG-4-SPDN boiler. It's been working great, up until today.

The standing pilot was on, but the boiler would not fire. Both zones were calling for heat. The transformer relay was buzzing loudly.

I jumpered the roll-out/spill-over switch, and the boiler fired.

I went and bought a new switch, installed it, and the unit worked for 15 minutes - the switch blew again.

I have confirmed that the electric damper is open. I have confirmed that the chimney flue is drawing (although the duct to the flue is black).

Any ideas as to what's going on? What I should do next?

Thanks in advance,

Cary
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- Weil McLain CG-4 boiler roll out switch blowing

Postby caryalon » Wed Feb 22, 2012 7:44 pm

I realize that the flame is too high...

I have a boiler tech coming out tomorrow, was hoping to have some more insight before he gets here.
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- Weil McLain CG-4 boiler roll out switch blowing

Postby how » Wed Feb 22, 2012 7:57 pm

Too much flame is unusual but not unheard of.
A more common cause for your roll out switches to trip are that the heat exchanger is plugging up and forcing the flames out the front. . When you look at the burner flames they will be burning lazily and often dipping below the surface of the burners.
Another cause can be from having insufficient combustion air around the boiler area. Check your fresh air inlet grill outside to see if it's plugged up with spider webs & dirt.
WARNING!
That roll out switch is all that is preventing co from spilling into your home right now or having all your gas controls bathed in flame.
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- Weil McLain CG-4 boiler roll out switch blowing

Postby caryalon » Wed Feb 22, 2012 10:13 pm

Thanks for the note - I have the boiler shut down. Insufficient combustion air shouldn't be an issue - I have a 4" fresh air duct drawing from outside.

Thanks!
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- Weil McLain CG-4 boiler roll out switch blowing

Postby how » Thu Feb 23, 2012 8:17 pm

A 4" fresh air duct drawing from outside won't work if the grill is covered with dirt. It's a pretty common find on my job. If you've checked the fresh air grill and it's clean..just ignore this note.

When you say that your flue is black, do you mean with soot. If so then your exchanger will probably be sooted up and will need to be cleaned out. A messy job for sure. The real question after you've got your unit working again is,What caused it?
Either oxygen starvation from badly adjusted venturi style burners or insufficient air for proper combustion.
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- Weil McLain CG-4 boiler roll out switch blowing

Postby heatseeker » Mon Feb 27, 2012 9:23 am

adding to what how said; insufficient maintenance will be your major cause,. never let your equipment get in this condition have it serviced annually.
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