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MegaSteam 396 oil fired boiler water loss.

Coopy Member Posts: 10
The boiler was installed in March 2021 by a local heating company, being the end of the heating season, it got a small amount of use for heating but used a lot for domestic hot water with the installed hot water coil throughout the Summer.

Immediately after the install I found had to add water to the boiler every three days to keep the recommended level in the sight glass (two thirds to three quarters full) The local heating company that installed the boiler says that water loss is normal and should be expected even though the manual states, anything over 0.7 gallon per month is not and voids the warranty if corrosion occurs, I am having to add 1-1/2-2 quarts of water (1/2 inch +) every 3 days to keep the level up and cover the hot water coil.

I have read extensively on this great site and others what to look for when diagnosing a leak, there is no leakage under the boiler, I don’t see any steam coming from my chimney, I have gone over every inch of my piping, there are no hidden/buried piping, all radiator valves/vents all work as they should, pipes are insulated even the near boiler piping, the near boiler piping has been done to specs.

My most recent discovery is that if I don’t add water to the boiler and let the water level in the sight glass fall to just under half full, it will stay at that level and after 5 days lose about an 1/8 of an inch.

I am absolutely baffled as to what can be causing this water loss and maybe realizing from the
old adage, that if it quacks like a duck… it is leaking?

After reading some Dan Holohan articles, I am taking his advice and adding boiled make up water via the skim port to reduce the risk of corrosion (Thank you Dan!) but it’s something I would prefer not to have to do.

I’m about to contact Burnham about what can be done under the warranty, not wanting to go that route unless absolutely necessary, I thought I would post the question here.

Can someone please help me with this?

Thanks in advance.


  • Jamie Hall
    Jamie Hall Member Posts: 23,567
    I should have hit control C control V... If the boiler is losing water when it is idle, the leak or leaks must be below the water line of the boiler. I'd like you verify this. Bring the boiler up to say 3/4 on the sight glass, and mark that level when the boiler is cool (I like spring clothes pins for that). Let it it, overnight, off. If the level drops, there is a leak or leaks below that level either in the boiler or in the wet return piping. Now. drop the level to the bottom of the Hartford Loop and again mark the level and let it sit. If the water level still drops, there is a leak in the boiler or, just possibly, in the very small amount of pipe involved in the Hartford Loop. If the level doesn't drop, the problem is in your wet return piping.

    Before you panic, however, don't overlook any drain valves. They don't always close tight.

    I might add that the amount of leakage you report is excessive, but it may not be particularly obvious. The amount you quote is less than a drip every 10 seconds -- so don't overlook anything.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Coopy
    Coopy Member Posts: 10
    Thanks Jamie, I will try what you suggest when I get the chance, weather permitting.
    EBEBRATT-Ed Member Posts: 15,767

    Sometimes you can have a small leak on the boiler and being a small leak and being hot it evaporates and you don't see any water
  • Coopy
    Coopy Member Posts: 10
    a small leak in the boiler evaporating did cross my mind and also the fact that it could only get worse over time.