A.O.Smith BTH500A 300

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Grallert
Grallert Posts: 1,237
in Plumbing

I hesitated to post this but I wonder if there is anyone with the same issue. We have a dorm building that occupies about 20 kids and two resident apartments. Commissioned 2017. Some time in 2020 the water heater failed. A combustion chamber leaked flooding the flame.

On the 9th of October the new one failed. Had a couple service companies out who diagnosed an igniter. I got one but no go. I was suspicious and pulled the burner assembly and found a flooded chamber again.

IMG_3298.jpeg

If you look closely you can see the fine stream of water jetting across the chamber. I don't know if any of you have have 25 teenagers side eyeing you but something had to be done in the short term so I drove a Sheetmetal screw into the hole and stopped the leak and I also pumped out the chamber. It's working now. I'll have the water checked but none of the other water heaters on campus are having issues. We are sort of locked into this heater due to the size and plumbing arrangement.

I guess I'm just wondering if this is not that unusual or has this been an issue for anyone else.

Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

Comments

  • Larry Weingarten
    Larry Weingarten Posts: 4,210

    Hi, I'd like to know more about the conditions this heater lives in. What pressures does it see? Is there much of a range? How heavy is the usage? Is there anything about the combustion air that's different, like chemicals stored nearby? Have you had opportunity to pull anodes to see their condition? Have there been any blue glass flakes in the sediment?

    With this info we can close in on possible problems.

    Yours, Larry

    GGross
  • 109A_5
    109A_5 Posts: 4,759

    " We are sort of locked into this heater due to the size and plumbing arrangement. "

    When you build yourself into a corner, you have to live in a corner. I'd go with a different technology heater, or a storage tank with redundant heaters.

    Seems like A.O. Smith got the warranty pretty much aligned with the units engineered construction.

    So the others are the same Make / Model with the same amount of daily use ? And have lasted much longer than 6 years ?

    BTW I've seen the bottom of an air compressor tank repaired with a sheet metal screw and some epoxy, if I recall it lasted a long time.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Grallert
    Grallert Posts: 1,237
    https://forum.heatinghelp.com/discussion/comment/1906416#Comment_1906416

    The heater is in a dry clean space. No chems. It get it's air from outside. I wauls say it gets heavy use, about 20 teenaged girls and two apartments with one adult in each and three small children. It shares the space with two W/M wall hung boilers also direct vent with outside air. It's kind of a dream boiler room actually. I'll get pictures.

    Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

  • Grallert
    Grallert Posts: 1,237
    https://forum.heatinghelp.com/discussion/comment/1906474#Comment_1906474

    I misspoke. There are ten water heaters here, various makes and models. Some basic electric 80gal tanks a couple atmospheric gas heaters a few indirects and another A.O.Smith but a smaller model, I forget the model #. I think, though I'd have to look, but we're at about 60? psi. Again I don't remember. I'll have a look this morning.

    Because of the venting and design use re engineering the system would be extremely disruptive and not likely to happen anytime soon if ever. I agree a redundant system with storage would be nice.

    Fingers crossed on my McGyver repair. Quotes are coming in.

    Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

  • Grallert
    Grallert Posts: 1,237
    IMG_3306.jpeg IMG_3305.jpeg IMG_3304.jpeg

    Still making hot water. Here's the mechanical room for anyone interested. Aside from all the head catching obstacles it a pretty good boiler room.

    Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

    GGross
  • pedmec
    pedmec Posts: 1,488

    The BTH500 is under a lot of stress when it kicks on. They have a large BTU output but a small body of water capacity in caparison. They continuously cycle on/off when used in places that require a large recovery. We replace these water heaters all the time due to failure within the 3-5 year range. We find that they are used in a lot of restaurants due to the small footprint they will occupy.

    Did the training in Nashville and it looks solid inside with the lining. i wonder how many hairline cracks develop in shipping as they are real heavy.

  • 109A_5
    109A_5 Posts: 4,759

    Maybe try an electric powered anode rod. All depends which side the major dilapidation is actually on.

    To me it looks like the dilapidation is on the fire side, closest to the fire, see where the rust seems to stop (Red arrow). The tube could be thicker or a different material if they wanted it to last longer (Orange arrow).

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Posts: 4,759

    Kind of wondering if a sheet of rolled stainless steel inserted would extend the tanks life or just cause some other issue.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,940
    edited October 19

    I see enough room for another Weil McLain Ultra 310 with an 80 or 119 gallon indirect. the indirect goes where the current AO Smith tank is and the WM boiler against the same wall as the other two . Minor relocation of the red tank might be needed.

    image.png

    The AO Smith vent pipe should be adequate for the WM because they are about the same size burner. You can select the 80 gallon tank that is close to what you have or the 119 gallon tank if you want more hot water capacity. I know it ain't cheap but if you are having problems with replacing a tank every 6 years, then maybe it ain't so expensive since those indirects last a lot longer and you don't seem to have a problem with the WM Boilers.

    You may not need the boiler if there is enough capacity for the indirects with the existing two boilers. That would take an engineer to do the math and that is easier now since you have a history of actual hot water use and actual space heating to input into the calculation.

    I only had one female teenager to deal with when it comes to hot water use, I can't imagine what 25 of them might be like to deal with. My teenager is in her 40s now and I have a grandson as a result of letting her live thru the teenage years. I feel that is my reward for allowing her to live thru those trying times.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Grallert
  • Grallert
    Grallert Posts: 1,237

    Thanks Ed this is a really good idea and worth looking at. For now we are or I am waiting on approval for a replacement. I have very little faith in the sheet metal screw repair. I'm sure we are all used to the fact that these thing in the cellar get very little attention until they break. We repair and folks forget until the next time LOL

    Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

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