Expansion Tank Problem?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by KathyV, Mar 22, 2008.

  1. KathyV

    KathyV New Member

    Messages:
    2
    I'd appreciate any advice, as I know nothing about this. Had a new Burham oil burner installed 3+ yrs ago. All was warm and quiet until this past December, much loud noise when circulator would kick on. I have a contact with reputable oil co. who came over and bled the line. Problem resolved. About a month later, noise (and air) problem came back to same degree. Oil co. returned and bled the line again, saying that temp. was too hot causing steam to build that relief valve couldn't handle, so lowered temp to 180 degrees. Everything is quiet for now, however, I now notice that when I turn the hot or cold tap on in the kitchen, that air shoots out first - 2x an hour apart. FYI, I have a single zone, closed system. Are these 2 issues related or just coincidence that happening at same time? Thanks
  2. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    noise

    1. The expanation that steam was building seems like a spurious diagnosis.
    2. Unless the boiler is heating the hot water, it cannot be connected. And even if it is heating the hot water there is something else happening to cause the air.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
    New England
    What is the system pressure? It's normally somewhere around 14-20#. If it is low, the boiler would normally shut off. If that pressure sensor isn't working properly, or the circulator isn't working properly, water could get hot enough to boil in the boiler. A hot water boiler isn't supposed to allow that.
  4. KathyV

    KathyV New Member

    Messages:
    2
    Pressure?

    I don't know the pressure; I don't know much in this area at all. Am at the mercy of oil company, which is why I am writing. Thought I could read up on suggestions and pose it to them at next call back.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,006
    Location:
    New England
    Frequently, a boiler will have a pressure gauge on it...you should check. There are often temperature gauges. SOmetimes these are monitored digitally, and can be read out on a display.

    While the boiler is running, the circulator must be running. It often runs for awhile after the boiler is off. If the circulator isn't running while the boiler is firing, the water can and often will get so hot it will boil in the heat exchanger. That will make all sorts of noises, increase the pressure, and cause the system to vent (and it often would turn itself off if the protection circuits are working properly).
    If you are lucky, the manuals are there for the boiler...they often have a theory of operation and troubleshooting sections. Even if you don't do yoru own maintenance, it isn't a bad idea to read through it to get an idea of what's going on, and what should be going on (not necessarily the same thing!). If you don't have them, sometimes you can get copies from the manufacturer's website...or call them and they may send you a copy. Very worthwhile having and reading.
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