Cost to replace expansion tank?

Discussion in 'Boiler Forum' started by jmoser201, Nov 25, 2021.

  1. jmoser201

    jmoser201 New Member

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    My expansion tank for my boiler has water in it and needs to be replaced. I had an hvac/plumber guy quote me $770 to replace it. Seems high, but he said the whole system needs to be purged and will take 4-5 hours to do that process. Does this seem right? We have an oil boiler which provides hot water to the baseboards for heat and an indirect water heater
     
  2. John Gayewski

    John Gayewski In the Trades

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    It actually depends on how the system is set up. Usually people skimp on valves or some inspector won't let you put a valve in to isolate the expansion tank. He's probably right.

    Tell him to install valves to isolate the tank for the future. Next time it'll be cheaper.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If the whole system needed to be purged, maybe...without being there to see what valves there may be to help isolate things, can't say...it could be all of a 15-minute job, but probably longer. TO keep from being scalded, the system needs to cool down first...that doesn't necessarily mean purge it all out, though.
     
  5. jmoser201

    jmoser201 New Member

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    Ok, he did say there was no valves to isolate the tank. Just wanted to make sure this all made sense. He also did mention something about putting in valves to make it easier next time
     
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  6. Sylvan

    Sylvan Still learning

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    I never failed a boiler inspection for NOT having an isolation valve to isolate the expansion tank

    Actually the NBBI and ASME does recommend it

    Your contractor is right on the money except he may have under estimated the time to purge all the air out
     
  7. Jeff H Young

    Jeff H Young In the Trades

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    Its outside my line but let us know how long it winds up taking the job through completetion.
     
  8. Sylvan

    Sylvan Still learning

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    I would love to meet ANY "inspector" who is such a moron who never bothered to read the ASME and has NO IDEA how to drain an expansion tank OR even service or replace one without a valve

    HOW CAN ANYONE remove a water filled tank without isolating it??

    How can it be replaced without a valve unless they like draining down an entire system?

    By the way I am a certified as a low pressure boiler inspector and installer I was also a did all the boilers for the North East regional postal service low pressure steam and HW and unfired pressure vessel inspections and I WOULD fail a boiler that had no means to isolate the expansion tank



    [​IMG]
     
  9. Sylvan

    Sylvan Still learning

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    Anyone notice anything wrong with the picture above ????
     
  10. John Gayewski

    John Gayewski In the Trades

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    No fitting on the tank.

    You can fail by having a valve on both sides of the tank. Most require it on one side of the tank so it can't be "shut off".
     
  11. Sylvan

    Sylvan Still learning

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  12. Sylvan

    Sylvan Still learning

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    Oh my your right and the industry is wrong obviously the ASME and National Board of Boiler Inspectors (NBBI) has published erroneous information,, Thank you for your expertise to enlighten me as this picture PROVES how correct you are that TWO valves cannot be used


    [​IMG]
     
  13. Sylvan

    Sylvan Still learning

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    YOUR right the National Board of Boiler Inspectors (NBBI) and the ASME are wrong

    After all it makes a lot of sense to drain an entire system down no matter how large to drain or replace a tank

    Normally to replace a diaphragm tank takes 15 -20 minutes USING your logic it should take several hours

    GOOD UNION mentality create extra work regardless of code requirements and decent heating practices

    EVEN this picture proves your right as TWO isolation valves are not to right and one should be removed huh?

    [​IMG]
     
  14. Sylvan

    Sylvan Still learning

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    I can fully appreciate the "training" you have as your knowledge is truly amazing

    Here is an another "failure" according to you

    [​IMG]
     
  15. John Gayewski

    John Gayewski In the Trades

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    So I'm not quite sure your point. Are you saying no one has failed an inspection for valving off an expansion tank? If that's you're point then your just wrong... AGAIN. There is a school of thought that dictates you shouldn't do this. I know people who subscribe to this school of thought. I personally don't think there can be enough valves, but no matter what you do there will be an annoying, time-sucking repair down the road. If it's not the expansion tank it'll be something else that could have used another valve. But hey that's why my advise was to have three guy install isolation valves.

    I don't really see what the union has to with anything, other than them probably kicking you out for doing something dumb, like putting the pump on the return, lol. And then arguing about it after its been proven superior and the industry standard for years.

    You should just talk another law suits some more. Even though I've never met a plumber who has been sued. It's very relevant to all of our lives.
     
  16. Sylvan

    Sylvan Still learning

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  17. Reach4

    Reach4 Well-Known Member

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    Quickly unscrew the old tank and screw on the new valve? Then put the new tank on at leisure. Remove air, but maybe not that much.[​IMG]
     
    Last edited: Nov 27, 2021 at 9:04 PM
  18. Sylvan

    Sylvan Still learning

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    https://pospislaw.com/wp-content/uploads/2013/08/Clinindin-v.-NYCHA.pdf
     
  19. Sylvan

    Sylvan Still learning

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    Don't you think it would be an amazing idea to first allow the water to cool before removing a tank under pressure?

    Have you ever tried to install a valve on the fly?

    Now just imagine trying to install a cap or plug on a HOT pipe with at least 12 PSI

    I wonder if the area he is about to flood is a finished basement?
     
  20. Sylvan

    Sylvan Still learning

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    From 2003 as appeared in plumbing mechanical

    He Said, I Said

    I happened to be in a home center this morning looking for some light bulbs when I came upon the plumbing department. A homeowner just happened to be looking for some advice and was asking the store person about pumps for his heating system.
    The store person said, "No problem. Take this one."

    At this point I had to say something and asked the heating salesman the following: Was this "pump" a centrifugal, rotary or reciprocating? He just shrugged his shoulders.

    I asked if this was a centrifugal "pump" was it horizontal or vertical? He said, "Let me look at the box again." I then asked if it's a rotary pump, is it a vane, gear, piston, lobe progressing cavity, peristaltic or screw type?

    He said, "Let me get my manager." A few minutes later the manager comes along with the store person and asks if he can help.

    I said, "You sell pumps, correct?" He said "Yes." I said, "What types do you sell for heating?" He said, "We sell one type that fits most applications." I said "Do you mind if I ask you some questions regarding this one-size-fits-all pump?" He said, "No problem. That's why I'm here."

    I said, "Fantastic. This one pump you sell: How does it know the TDH of the system and the required flow rate?" He asked me what TDH was, and I told him "Total Discharge Head."

    I was faced with three blank looks.

    Finally one said it doesn't matter because the pump "knows" what it needs to do. I said, "What about pipe loss and Hazen Williams formulas or Darcy formulas or the friction factor based on Reynolds number and laminar flow as opposed to turbulent flow?"

    Then another store employee came over and said he was a plumber. I said, "Great. Where are you licensed?" He said he didn't need a license as he knows it from doing it. He then went on to explain why this great pump is automatic and can handle all kinds of water as it only draws the power it needs to move water around. I asked how fast does it move the water? He said a few miles per hour, with that I left the store saying thank you.

    Now I am curious as to how insurance companies pay off claims to non licensed folks dabbling in very technical trades. Here we have stores selling "pumps" to anyone who walks through the door thinking they can get a crash course from these shopkeepers in blue jeans.

    Let's make it mandatory that to buy this type of equipment that the buyer must require proof of a license to show they know what they're doing. I know when I went for my hunting license I had to show proof of taking a hunting safety course. It's a national disgrace the number of folks who die from bad installations that are done without requiring formal training by anyone tinkering out in the field.

    Sylvan Tieger
    S. Tieger Plumbing Co. Inc.
    Riverdale, N.Y.
     
  21. Reach4

    Reach4 Well-Known Member

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    I was assuming that the system would be cooled first.

    Attempting that would be silly.
    I have not actually changed a pressure tank, or expansion tank myself. I have just tried to picture it. I also have only had hot air heat. Hydronic does seem like a really nice upgrade.

    I was assuming a basement or other place not so subject to water damage, and that a wet-dry vac or some towels could take care of spilled water. Maybe catch water with a bucket or wading pool or plastic drop cloth.

    It seems to me that after turning off the boiler, and closing the supply feed, you could release pressure via the Schrader valve on the old thermal expansion tank. Let system go cold. I picture having the new isolation valve already connected to its nipple, tape and dope the nipple, and once the old tank is pulled, the new nipple would get screwed in.

    If this is done in really cold weather where you need to minimize the time that the heat is off, that would complicate things.
     
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