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Steam heat - Losing Water

Last heating season, my water level in sight glass would be down considerably after adding water (an inch or 2 after 4 days or so). Even this summer, with furnace off, I notice a little bit of loss, not like heating season of course, but noticeable. I do not see any puddles at all under the furnace...any pointers??


  • HVACNUTHVACNUT Posts: 2,768Member
    Can you post some pics of the boiler and piping?
    Is the return pipe(s) coming back to the boiler above or below the boilers normal water line?
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,312Member
    check and see if you have any return pipes buried in the basement floor. #1 cause of loosing water
  • Al07601Al07601 Posts: 2Member
    edited August 2019

    These are series of views of return from main vent going down, then going to the right. Then going around corner (this is top view looking down)...then long straight run to back of boiler. Then shots of piping around boiler.
  • nicholas bonham-carternicholas bonham-carter Posts: 8,047Member
    edited August 2019
    Do the overfill test. Fill the boiler up to the header, so there is 6 inches of water in the supply pipes leaving the boiler, and let it sit overnight. Any leaks from the boiler will show up on the floor.
    If you discover a leak, make sure that the replacement boiler is properly sized to the capacity of the radiators, (see EDR), and have the boiler properly piped to the manufacturer’s installation diagram, which it is not now.—NBC
  • KnavePKnaveP Posts: 21Member
    I had this issue and turned out that the radiator vents were not closing. There was a continuous stream of steam coming out as long as the heat was on. Replacing the vents resolved the issue. A flash light on the vent will illuminate the steam.
  • gfrbrooklinegfrbrookline Posts: 579Member
    Radiator vents shouldn't be an issue if you are loosing water when the boiler isn't making heat.

    How much loss did you see and over what period of time? You may just be experiencing normal evaporation over a hot summer.

    One thing I noticed is your main vent is probably way too small and is in the wrong place so it may be stuck open which will cause your water loss. The vent should be 18" from the drop and up at least 6" to prevent damage to the the vent. If that vent is stuck open during the heating season you will loose a considerable amount of water.
  • gfrbrooklinegfrbrookline Posts: 579Member
    Your near boiler piping is also all wrong and the rest of the piping shows signs of sections of steam that were removed strangely to say the least, lots of short pipes with caps. Does your building heat evenly and quietly?
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