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How to Save a Boiler's Life

HeatingHelp Posts: 464
edited July 2020 in THE MAIN WALL

It's a given these days that all boilers have low-water cutoffs and that makes me very happy because I've seen hot-water boilers explode.

Read the full story here


  • pitman44
    pitman44 Member Posts: 18
    Many years ago I felt a LWCO was a redundant item since all water boilers had automatic fill valves. Then one day I read an article, probably by Dan H, on the impact a stuck closed relief valve had on a boiler with a failed closed high limit. In my mind's eye I could see that boiler lifting through one of our customer's children's bedrooms. As a dad myself we started testing the relief valves on every boiler we serviced. We found many that wouldn't discharge. Some of them because the relief valves had failed, but others didn't discharge because there was no pressure in the boiler. The fill valve or the backflow preventer had failed. Those boilers were halfway to extreme failure without a LWCO. That's when we started recommending a LWCO on every boiler.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 15,425
    Thanks for that.
    Retired and loving it.
  • retiredguy
    retiredguy Member Posts: 487
    edited July 2020
    Good story Dan and very informative. I probably should have filed this under boiler disasters then thought that it may be worth mentioning here. My best guess would be that everyone who has been in the boiler business knows that all these gas, oil, or coal fired boilers are a potential bomb or disaster. In my 40+ years I have seen and/or witnessed numerous boiler failures usually due to poor maintenance or poorly trained personnel. I witnessed 2 coal boilers melt the fire tubes and in 1 case even melt the stay-bolts in the fire box due to a low water condition. Coal boilers do not have a low water cut-off for obvious reasons but instead have a loud whistle that annunciates when a low or high water condition is present. That whistle is the boiler operator's warning that a dangerous condition is happening. In both these cases the whistles were not operable.

    A residence exploded due to the owner plugging the relief valve due to the cost of a new relief valve. I was told that this persons family was in the house but I do not know that for sure.

    A miss-wired secondary low water control caused an H B Smith boiler to melt it's sections at an elementary school in northern Pa.

    Poor workmenship caused an H B Smith boiler in a school south of Pittsburgh, Pa to "come apart" due to a firebox explosion when firing #2 fuel oil.

    This was a situation that I was told about and saw the story in a newspaper article about a boiler exploding at a factory somewhere down south around North Carolina where the boiler left the premises together with the concrete floor it was bolted to and "flew" across a major highway into a wooded area. The company I worked for was said to have supplied the boiler to the original customer many years earlier but that we hadn't been on that job for many years.

    Defective controls are another cause of boiler explosions that I was involved with in schools, hospitals, factories and etc. Even when the customer was warned of the controls condition many of them were reluctant to replace the control due to cost or something else.

    We never used the term explosion but instead referred to them as a "rough" light off. Being a witness to these and other boiler mishaps makes you be very careful and to double check yourself and be extra careful after other people have been there.
  • LynnLennox
    LynnLennox Member Posts: 23
    Believe it or not I was never told to regularly flush my low water cutoff. I arrived home from a trip and that night the boiler ran out of water. The float was stuck, so the boiler kept running. I awoke to the smoke detectors going off ndathe house filling with smoke. My 2 teenagers were sleeping through it. I got us and the pets out of the house. I did not have an automatic water feed. With the new boiler, came an auto feed. However, twice that malfunctioned and started overfilling the boiler. Thankfully I was home both times and knowing how long the auto feed usually kicked in for, I knew something was wrong. It was running too long and repeatedly. The auto feed no longer works and I don't trust them enough to replace it. Once a week we flush the low water cutoff and add water as necessary to the boiler. Buyers of old homes with steam systems really should receive an orientation from the annual maintenance guys. I seem to have learned everything the hard way. Thankfully with no injuries or damage to the house.
  • Skyline
    Skyline Member Posts: 112
    The LWCO can also fail open at the most in-opportunistic time, that shuts off the boiler. In the middle of the winter, late at night, there isn't much choice, but to put a jumper in to the leads.

    After testing both pressure relieve valves and making certain, that the boiler pressure is where it should be of course...
  • Steamfighter49
    Steamfighter49 Member Posts: 9
    I found a steam boiler once where the operator hardly ever blew down the LWCO. After a while no water came out so he stopped trying. The reason was sediment had built up inside the LWCO. When I investigated the ‘ no heat’ call I eventually found a perfect impression of the float in the, now solid, sediment inside the LWCO bowl.
    What saved this building? There was no heat because the neoprene gasket above the pilot flame burned out and the last bit of water left in boiler put out the flame. If not the boiler may have blown. It was a pre-school facility.
    Maintenance must be constant and done by trained people. I trained him before we left the regasketed boiler.

    Btw, what’s with the centigrade temps? We’re still using Fahrenheit in this country, aren’t we?