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Steam Boiler not Firing


I'm suddenly having an issue with my steam boiler. I have a Weil-McLain EG/PEG-35 which was installed in 04 or 05 (prior owner) with a Safgard Model 400 low water cutoff. We had a township inspector out this morning to check the chimney liner so I flipped the main burner switch to off. I do this from time to time when I flush the unit out.

Fast forward 12 hours later to this evening. I get home, flip the burner switch back on and turn the heat up. Instead of firing, all I'm getting is a rapid clicking on/off sound from my low water cutoff unit. It clicks for 10-15 seconds, stops for about 30, clicks for 10-15 seconds, stops, and then sits there. Any idea why this thing isn't firing? I've never had a problem with it before.

The gas is on (I've since turned it off just to be safe), the unit is getting power, and there's sufficient water. It might be the pilot light but I can't manually light it. The unit has an auto pilot light. I have no idea what could have changed in the 12 hours no one was around. If anyone has any idea as to why this won't fire, I'd really appreciate some insight.

Thanks in advance!


Re: Steam Boiler not Firing

It could be any one or more electric or gas part(s) along the way.

Start checking them one by one. Pilot, thermocouple, relay, gas valve, gas supply - The fact that it worked 12 hours ago is irrelevant.

If it's too much for you, call a tech (but don't call an inexperienced tech who will recommend replacing all parts).

Re: Steam Boiler not Firing

The water level is to low or the low water cutoff failed. What dose the water level in the gauge glass look like?


Re: Steam Boiler not Firing

Do you have enough water in the boiler???? Can you see any water in the sight glass situated at the front of the boiler???

How long has it been since the boiler has been cleaned??? Sometimes the base of the sight glass can get clogged with minerals so that it doesn't drain & falsely indicates that there is enough water in the boiler when there isn't!---in such a case the boiler has to be shut off & the sight glass assembly removed for cleaning.

Steam boilers are unique in heating equipment in that they have to be attended to weekly (sometimes daily), especially if you have hard water----minerals & other deposits gum up the water & a "blowdown" of 1/2 gallon to 1 gallon of water has to be done at the boiler drain often every 2nd or 3rd day to get rid of the dirty water that can gum up the controls.

The Safgard Model 400 control is a low-water cutoff (LWC) device that is designed to interrupt the electrical circuit of the gas burner when it detects a low water condition in the boiler, this prevents a dry-firing into the boiler that would damage the combustion chamber or boiler jacket---so your first impression should be that the LWC is DOING ITS JOB of protecting the boiler from a boiler low water condition that could damage the equipment; as noted above where the lower part of the sight glass may be clogged giving a false reading of a boiler FULL OF WATER, when it's actually low on water; you first have to make sure there is enough water in the boiler---shut off the boiler & blow off some water into a pail at the drain valve at the base of the boiler & check if the sight glass level changes; clean the sight glass assembly if there is a problem; add new water to 1/2 or 5/8 of the sight glass level if all is well & turn on the boiler.

Some of these units have a manual reset button you can press if you see one on the unit, others have an internal automatic reset.

If the boiler water is dirty due to lack of maintenance or you have hard water with a lot of minerals, the probe of the Safguard can get coated with crud so the control can no longer complete the electrical connection to the interior metal wall of the boiler---if this is the case, the boiler has to be shut off, water drained down below the level of the LWC , so that the probe can be removed & the probe end cleaned with a piece of steel wool & the unit re-installed-----see site below for guidelines.

Consult your boiler Installation & Operating manual, if you have one, or Google the boiler model # to get the one on the internet for a download & printout; also Google such phrases as "steam heat not coming on", LWCO chattering", "LWCO noise", etc.-----in your search process you will encounter other sites that specialize in servicing steam boilers.

Call in a service person if all else fails.


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