Steam boiler cuts out at night, works fine after being off for a few hours

riles246

I purchased a home this summer and am trying to get the heat started for the season. Per the purchase inspector's advice, I drained the boiler until the low water mark on the sight glass and refilled prior to starting for the season. I then flipped on the burner switch and set the thermostat a couple degrees higher than ambient and I heard the pilot ignite (a couple of clicks then it was on), then the main burners came on. A few minutes later we had steam and the house warmed up nicely. I let it run for the night but it wasn't that cold out, so I don't know if it even had to cycle again all night.

Fast forward to a week later, it is now cold enough at night for the heat. When I set the thermostat to "heat", everything works at least once. The burners light, the water boils, and the home heats up. However, everytime I wake up in the morning, the house is 3-4 degrees cooler than the thermostat set point. I flip the burner switch off and back on (thermostat still calling for heat), and I hear/see the flue close and re-open, then the pilot attempts to ignite but all I hear is clicking- no gas is flowing. This goes on for about a minute then it gives up trying to light. The water level is fine per the sight glass and the main gas valve is on. Interestingly, the boiler is still hot, although I can touch the steam pipe without injury so clearly it hasn't run in a while. If I shut everything off for a few hours and let it cool all the way down, everything works again.

Does this sound like something obvious? I have a thought that it might be the low water cutoff giving a false reading since it makes a loud click when I turn the burner switch off and on during this time but not when cool. I read an article on the internet about how to bypass the probe to test it but can't quite make heads or tails of how to do it. It is a Honeywell Guard Ring with a probe sensor, but no switch in the "test" knockout.

My other thought is that perhaps it is related to the pressure. The cut-in is set at the lowest possible setting but I don't see an adjustment for the differential, and the gauge doesn't seem to work since it has always said 2.5psi (boiler off, cold, hot, no difference).

Ultimately I would love to just call someone to get it serviced but I'm new to town and already had a very bad experience with one of the bigger repair chains so I'm not sure how to find someone trustworthy.

Thanks in advance!

Jamie Hall

There are so darn many things this could be -- but whatever it is, a) it's a control problem of some kind and b) your very best bet is to find a competent steam man to come and check and adjust the system.

Have you tried the "find a contractor" tab? By state works best. Either that, or tell us what town and state you live in and we may be able to steer you to someone.

riles246

Thanks for the quick response. I agree, definitely not my area of expertise! I'm in Bergen County NJ, but I will use the Find a Contractor tab

Fred

My first guess is that the pigtail that your Pressuretrol/Vaporstat is mounted on is plugged with gunk. That pigtail should be taken off and cleaned out every season. They get clogged up and then the Pressuretrol does not get an accurate reading or the pressure is held in that tube and it takes several hours for it to relieve itself as a result of being plugged up. I'm willing to bet the next time the boiler won't come on that if you tap the top of the Pressuretrol, you'll hear the burner kick on. give it a try.