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High water usage in a steam boiler

ruggb
ruggb Member Posts: 6

I am trying to help solve a problem with our church boiler. I have found a number of similar posts but no one has ended the post with a solution.

The boiler appears to be using about 250gal a month with no sign as to where the water is going. The boiler is about 8 yrs old. It has a chemical injection that may not have been set right till recently. And I don't know how long the problem has existed. I have searched most of the condensate lines with a thermal camera but found nothing I could define as a leak. Most of the pipe is in walls or in concrete floors so it is hard to tell. I may have a bad backflow valve in the condensate return to boiler line as the temp on both sides of it quickly returns to a high temp the same as before the pump runs. I periodically get water discharge from the condensate tank overflow, but that doesn't account for the amount of water being lost. The pressure gets a little high. It should be about 10 but gets to about 15 before it shuts off. How might that be causing water usage?
What other symptoms would a bad backflow valve exhibit? How might it be connected to the water usage?

Comments

  • neilc
    neilc Member Posts: 2,954
    edited January 6

    that's a LOT of makeup water, no good,

    all that return pipe under the slab,

    try and trace it with the thermal cam,

    the leak(s) should show a swelled pattern next to relatively straight heat signature of good pipe,

    or replace it all, it's time,

    known to beat dead horses
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,987

    Taht is a ton of water to lose very bad for the boiler.

    If you have pipes under the floor that is the first place to look. Also, shut the boiler down and add water to flood the boiler until the supply coming out of the boiler is cold. Let it sit a while and see if the boiler leaks. Look inside the boiler and underneath

  • neilc
    neilc Member Posts: 2,954

    and why 10 ?

    that's a lot of pressure unless the priests are brewing beers

    known to beat dead horses
    Neild5delcrossv
  • Jamie Hall
    Jamie Hall Member Posts: 25,372

    That 10 psig is either good news — or bad news. Is there a reason it's so high? Fan coils, maybe? Or… just why?

    On the other hand, with pressure in that range, it's not going to take much of a leak in terms of physical size on the steam side to lose that much water. It is quite possible that it is in the boiler itself; you'd not see any water from that, but at that rate of steam loss you should see it in the exhaust from the stack — unless it is steam side to air, which is rare but not impossible. I would think the humidity would be noticeable in the boiler room, but… maybe not. However, if it is a steam leak somewhere in the piping — particularly if the sanctuary is at all large or draughty or both, you might not see it at all — but I'd be rather surprised if you couldn't hear it.

    You would, I think, notice it if it were somewhere in the visible piping. You'd often not see it if it were in any of the buried or concealed piping.

    Now. When things outside warm up a bit and you can shut the boiler down for a day or so to let it cool, do the usual things to try and pinpoint leaks. To check the wet returns, since you have a condensate receiver, fill that to the top and observe it. If there are low (condensate) returns which are above that receiver, however, that won't check them. You may be able to rig a system on the vent, however, so you can raise the water level in the tank up to at least the top of the boiler and observe; if at all possible, fix that check valve wo that water can't get back from the boiler to the condensate tank before you try that (so you are isolating what happens in the piping from what happens in the boiler). Observe. If there is a fall in water level in either of those tests, it's in the piping.

    Now. The boiler. First, fill it at least to the header, but try not to go higher (you WILL need to fix that check valve for this) and check if the level holds (you can attach a hose to a handy drain fitting and raise the end to where it overflows, since you won't be able to see it in the sight glass). Observe. Level drops? Problem is somewhere in the boiler. Now lower the water level back down to just below the Hartford Loop and observe. Level drops? Problem is still in the boiler, but below the water line.

    And please report back on what you find!

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ruggb
    ruggb Member Posts: 6

    Thank you all for the quick responses. I am going back today (it is currently 35°F outside) to try again with the thermal cam. There have been no visible leaks. So, if there is one or more it has to be in the buried pipe. Last time the straight pipe showed less signature on the cam than the 90° turns, which were quite visible. That seemed to be the case even for the visible piping.

    I will recheck the pressure variation. I am going on my foggy memory on those figures and it may not be right. Now I am thinking it is set at 3 and it goes to 5 max. That sounds more reasonable, right? But I will check with the priests. It might be a good brew.

    Someone readjusted the chem mix which is supposed to reduce the bouncing of the water, and no one has tried overfilling yet. Someone else is leading this effort and has more history on it, so I will share all this info with him.

    So far, we have not seen any vapor coming out the chimney, but I know that is not necessarily visible.

    I will definitely report the outcome.

  • ruggb
    ruggb Member Posts: 6

    Another question….If the boiler is overfilled, but doesn't have a defect leak, will the overfill be evaporated out the chimney? If that were the case and there was a condensate blockage that delayed the return causing water to be added creating an overfill - that could explain the usage, right?

    There is norovirus going around at church so my activities for today are cancelled. My wife has an operation next week and can't be sick. However, I just talked to the lead guy and he ran the system last night with all zones shut off and it still used 2 gal/hour. Even with the zones off, he still heard condensate coming back to the reservoir. Is that a clue?

  • Jamie Hall
    Jamie Hall Member Posts: 25,372

    An overfill will cause all sorts of interesting problems — but the excess won't be evaporated out of the chimney unless there is a leak in the boiler itself. That leak location is the only one which can get water and hence steam into the fire chamber and out of the chimney.

    What may happen, though — although I think you said you had checked it — is that if excess water is being added to the condensate receiver it can (and should!) flow out of the condensate receivers vent or overflow, and if those are below the boiler operating level that wouldn't overfill the boiler — but could account for any amount of excess water. You might double check on that. The vent should be well above the operating level — but the overflow could be just about at the operating water level.

    Check that backflow valve again… and look for leaks or overflow right around the condensate receiver area.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ethicalpaul
  • retiredguy
    retiredguy Member Posts: 996

    In most steam systems like yours there are only a few places that water can be lost. The first place to look is from a cracked or a deteriorated boiler section. Here, the water would be on the floor under the boiler when there is no steam and the boiler is not firing or it could be being carried up the chimney as a vapor when the boiler fires. The next place I would look is at the underground condensate lines. My best guess is that this is where the majority of the water is going. Instead of a thermal gun I would remove my shoes and socks and walk on the floor where you think the lines are. A warmer spot in the floor will tell the tale. You could also use your hands but why crawl when you can walk upright. AS for the check valve being bad. If you suspect it is bad, replace it. Install one at the pump discharge and another at the condensate inlet to the boiler. A bad check valve on the condensate line will not cause you to lose water unless it causes the boiler water to back through the pump and cause the pump to loose prime or cavitate. Lastly, post a few pictures of the boiler and one or two of the heating units. If this heating system is an old Iron Fireman Select Temp System then that is the reason for the high operating steam system which needs about 10 PSIG to operate correctly. I hope you do not have a Select Temp system.

    Long Beach Ed
  • JUGHNE
    JUGHNE Member Posts: 11,317

    You can see water come out of cond pump overflow, does it have a separate vent pipe that could be passing steam. Especially if it is vented to the outside, that may be unnoticed.

  • ruggb
    ruggb Member Posts: 6

    RE the backflow valve, what I have is two pics. One when the pump is running and the temps on both sides are lower. The other shortly after the pump stops and the temps on both sides are high. To me, that indicates the valve is leaking. I haven't verified that the pump is running because condensate is flowing in or because it is backflowing. The only "leak" in this area is the overflow pipe. And that is minor compared to the replacement volume.

  • ruggb
    ruggb Member Posts: 6

    I probably won't be able to get back to it till next week as wife is having a hip replacement. When I do, I will take a few pics. What I am looking for with the thermal cam is a larger area of warmth around the pipe than just the pipe. But I haven't seen that yet. I don't think my fet would detect that as well as the cam. But I might try that.

  • ruggb
    ruggb Member Posts: 6
    edited January 8

    It is not venting outside. Just onto the floor and into a sump.