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Water Level - One pipe Steam Heating

Hello,
My question is based on water level and steam efficiency. My current tenant is afraid of the steam boiler water line being too low, and is constantly checking and adding water to the boiler when its not necessary. I assured him there is a low water cut off probe installed to prevent any issue of the water line being too low. I'm not complaining, however are there any pros or cons to him keeping the boiler water line level too high for steam heating efficiency? Just curious.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,967
    Not really -- the boiler will work best with the water level somewhere in the middle third of the sight glass, but so long as the water level is below the top of the glass it shouldn't be an efficiency problem.

    Constantly adding water, however, is a problem: a steam system in good shape shouldn't need more than one or two gallons a month (unless it is very big indeed). Might be worth seeing if you can figure out just how much water is being added.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bigbri0104
    Bigbri0104 Member Posts: 28
    Thanks for your input. Its a small residential system. I think my tenant will check the sight glass when the boiler is running, that's why he thinks the water level is low. I need to explain to him, in order to check the water level, shut the boiler emergency switch off, let the boiler sit for a few minutes allowing the water and condensate to return to the boiler, then check the water level in the site glass.
  • Jamie Hall
    Jamie Hall Member Posts: 22,967
    Nice to have a tenant who's concerned. So many aren't! Now to get him to understand that the water level will be lower while it's steaming, and to wait for a few minutes after it has shut off... !
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bigbri0104
    Bigbri0104 Member Posts: 28
    agreed
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 984
    You can try to impose a small amount of discipline on your tenant until you are sure he is not just a worrywart and more of a hindrance than a help. What I am going to suggest involves some effort on both parts, but can lead to a better long term outcome.

    If you can't be there with him when he wants to do something, coordinate with him over the phone or videocon him so you know the exact system conditions when he wants to add water. It depends on how often he adds water as to how much effort is needed. You might be able to pick a certain time every so many days. Keep a detailed log/diary

    As far as heating efficiency, think of two extremes, lowest level before adding and highest level after filling.

    The more water in the boiler, the longer it takes to heat the water to steam temperature, then to make steam, but there is more residual heat available (potentially as steam to the system, depending on operating pressure) which may sustain the heat supply time for a time...I have no idea if it's seconds or minutes.

    At the lowest level, more of the heat exchanger is exposed as steam space and possibly hotter than the portion of the heat exchanger in contact with the water, potentially heating up the boiler a little faster thus compounding the effect of less total water to heat up...again I have no idea how much of a contribution there is to faster steam generation.

    Let's see if I can create a valid example:

    My auto feeder adds 2 gallons per cycle, so with a starting temperature of 62 and a steam temperature of 212 that's 150 degrees or 150 BTU/lb times 2 gallons times 8.3 lb/gallon or 2490 /BTUs. For a 150,000 BTU/hr heating rate (just an arbitrary number) it will take 2490/150000 = .0166 hours = 1 minute to heat up that additional amount (ignoring any other factors for simplicity).

    So it's at least a minute...not very much in my line of thinking.

    Bigbri0104