boiler burner malfunction

William Faust

My Weil-McLain LGB 6 steam boiler's gas burners are supposed to burn gas only at top throught slots. They periodically malfunction by also burning gas at the gas jet's two ends where the gas nozzles are located. I'm wondering why, but I'm more interested in fixing this problem. Any ideas?

Ed_26

gas burners

Sounds like it's time for a service tech. - one with all the tools. Should do complete cleaning, pressure checks/adjustments etc.

ttekushan_3

be sure

that there are the required two (2) ignition modules and that they are hooked up properly to the two gas valves as per WM installation literature. The first valve is pilot burner, pilot being lit by first ignitor. Once the first module is satisfied that the pilot's lit, its MV connection energizes the second module whose PV opens the LOW pressure portion of the second gas valve while spark igniting the other side of the burner assembly. Then the second ignitor energizes its MV connection which turns on the HIGH pressure portion of the second gas valve.

If for any reason this procedure is missing a step and moves too quickly to the HIGH fire position, the burners will sometimes fire "inside" the flame tube/rod or whatever they're calling it these days. The flame is visible eminating from the orifice.

The problem is most pronounced on cold starts or poor draft conditions. Especially if the boiler is leaking at all.

I've seen the second gas valve's low and high fire positions shorted together due to the valve sticking and failing to open, thus causing the ignition sequence to time-out. Connecting them together is the quick and dirty solution, but causes a very ungraceful (wooofff) ignition, fume rollout and the symptom you describe.

Adjustment of the low fire pressure by a professional may keep the sticking from occuring, but a replacement valve is usually indicated if this trouble persists. Also check main gas pressure and gas line sizing against WM literature.
THIS MUST BE CORRECTED.

-Terry

edit: and it wouldn't hurt to make sure the little slotted vanes on the burner tubes are clean!

J.C.A._3

Sounds like....

Ed has the right answer...to me anyway.

William Faust

woofff!

Funny that you should use that wooofff to describe a sound because that's exactly the way it sounds when a couple of the burners (only one or two at a time) fire not just at the top "slots" but also at the gas orifices that point into the burners.

To check for boiler leakage, I filled it up the header and left it that way for a few hours and I did not see any leakage onto the floor. Should I consider this conclusive?

It sounds that you are on the money, so I will have a replacement valve installed. Main gas pressure in Philadelphia is notoriously low. The gas line sizing is correct.

Thanks very much for your input. It is greatly appreciated.

ttekushan_3

yup

water vapor caused by excess water leakage is not your boiler's problem. Probably fine. Go ahead and have the valve replaced and everything adjusted. should be OK.

tim smith

Good cleaning first

> Sounds like it's time for a service tech. - one

> with all the tools. Should do complete cleaning,

> pressure checks/adjustments etc.



I agree, good service/cleaning is more likely needed than new valve. If burners are partly clogged it creates back pressure allowing gas to burn in venturi of burner. JMHO Tim.