Thermal Expansion tanks.....average life span???

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Master Plumber Mark, Jan 28, 2008.

  1. We usually offer a thermal expansion tank when we
    install a new water heater.....and a pan under the heater....

    I had a Rheeem gas heater today begin to leak....

    It was 6 1/2 years old......not too good a life span...

    We replaced it with a Brad a new pan pipled to the crawl space...

    The problem that I ran into was the Thermal expansion
    tank had gone bad some time over the last 6 years and
    weighed about 55 lbs just hanging in the air....

    the homeowner was disgusted enough with the fact
    that the heater had gone bad, and did not want to pay extra for
    a thermal expansion tank that I had promised her 6 years ago
    would help lenghten the life of the heater...

    so I put a plug in the outlet,
    and went my merry way....

    I recently had a thermal expansion tank that I had
    installed about 8 years ago blow a hole in the side of
    it and get a basement pretty wet......

    I am not to happy about the cheapness of those things
    and am glad I have not have had to pay for anyones
    basement as of yet.............

    My question is .....
    how long are those things supposed to last???

    Do any of you actually send out mailers, or remind
    your customers that these things should be serviced or looked
    at after a few years????/

    or is that simply their problem after a year????

    basically what good are they if someone
    does not check them out and baby them every so often for troubles....
    Last edited: Jan 28, 2008
  2. Gary Swart

    Gary Swart In the Trades

    Yakima WA
    Gosh, Mark, I sure don't know the lifespan of an expansion tank, I would guess it would be as unpredictable as the life of a water heater. I hope you informed the customer that her TP would likely be opening whenever the tank heated. The good thing is, when she calls crying about that, you will already know what has to be done. Just take her a new tank, remove the plug, and install the new one. You make a good point about professional installers at least giving instructions about check them. I do fear however, it would have about the same results as telling them to flush the tank annually.
  3. patrick88

    patrick88 Plumber

    Webster Ma.
    I think it x-troll tanks and well-troll tanks last for a few years. Just like everything else in a home owners house they need to check things out once in a while. I'm sure you have had those customers that have not been in there basement for years. I'm also sure you have had customers that have know idea were there water main valve or any other valve is.
    I bet if a few Plumbers sent out mailers to customers for a free or low cost Plumbing check they would make some $$$ in the long term.
  4. I replaced 144 expansion tanks last year at the tune of $75 a piece.

    I only installed/replaced 89 PRV's though, same price. Not including labor.

    You have to always check them along with the checking pressure when you do work at a home, sell the use of them as it's a required method to correct thermal expansion.

    I've used Cash Acme, Well X trol, Watts, some other brand but can't remember what it is.

    Haven't been any bad ones yet, going 5 years now.

    It's all about how you market the product and convince the customer the necessity of the product, knowing high water pressure is very detrimental.
  5. Redwood

    Redwood Master Plumber

    Redwood makes note to sub out all expansion tank jobs to Rugged. He does it below cost! I think the last tank I bought was around $50 parts cost!
  6. Cass

    Cass Plumber

    I assume you checked the water pressure...most, not all, Exp. tanks that I see that have failed within 6 years of being installed were due to failed PRVs.

    I have, in the past few years, changed the way I install Exp. tanks.

    I have them pressurized about 1-2# above the water pressure. I do this because I believe the bladder inside will stretch like it should better while operating because it begins its expansion because it is expanded into its dome shape at the start.

    If the tank pressure is set a a perfect balance with the water pressure the bladder will be deflated and pushed up against the connector. When the water expands the bladder will in a few place have sharp bends/corners and will bend there instead of stretching and like anything that bends sharply in the same place over and over will fail at that spot sooner than it should. This is just my own thoughts and idea on this.

    Maybe I am all wet.:)
  7. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    did not want to pay extra for
    a thermal expansion tank that I had promised her 6 years ago
    would help lenghten the life of the heater...

    How would it do that, and why would you tell her that? It has nothing to do with the life of the tank, and everything to do with minimizing excessive pressure buildup from thermal expansion. About the only other thing it does is possibly extend the life of the T&P valve because it is not continually opening and closing. I assume it WAS on the cold water inlet line, because hot water will accelerate its deterioration.
  8. riverbend

    riverbend New Member

    Training / Education

  9. $32 per tank cost but I buy 50 at a time

    Add what I charge per tank, plus my hourly rate.

    PRV & EXP tank installs usually run $400, less if there was an expansion tank existing. *less copper work*

    The ST-12 tanks are more expensive, usually $46 cost if I buy 20 @ a time.

    If I gauge how many I'm putting in this year already, 3 of each, that's it.

    I expect my numbers to drop sharply because I'm avoiding water heater replacements these days.
  10. Bob NH

    Bob NH In the Trades

    New Hampshire
    Here is an engineering solution for you.

    You might want to make it a practice to install only PRVs with a built-in thermal expansion bypass and skip the expansion tank that is susceptible to failure. I believe that is the B option on the Watts PRVs.

    Most customers would be happiest not having another potential leak and failure built into their system. The TP relief valve on the water heater provides protection if the PRV fails and that leakage is usually something you can deal with.
  11. jimbo

    jimbo Plumber

    San Diego
    The bypass in a PRV will prevent the house side water pressure from exceeding street pressure. But that is too high. Common street pressures are in the 95 to 140 range around here, and you really want an expansion tank to not let your pressure creep up that high.

    In my experience, anything over about 110 will often cause weeping of the water heater TP.

  12. The thermal expansion bypass opens at 135psi and only if the incoming pressures isn't matching or higher.

    An expansion tank will accomplish protective measure to within 1/2 pound of deflection and up in the device.

    I'm sure they could make a product that would last but that would knock someone out of the job; can't have that on the mfg. side of the equation.
  13. SteveW

    SteveW DIY Senior Member

    Omaha, NE
    Alternatives to thermal expansion tanks

    If you go to Watts' web site, you'll see that they manufacture a pressure-relief ball valve designed for use with WHs. You can get them with preset at 75, 80, or 100 psi.

    Watts also makes, or at least used to make, a toilet ballcock with a built-in 80 psi (I think) pressure relief valve.

  14. Those work steve but both expel/waste water when performing the task of eliminating thermal expansion, both will eventually clog and fail over time.

    I'm well versed on this subject matter, glad it came up as it's important for the viewing public to understand these matters in regards to water supply systems.

    The technology isn't new but it is new to homeowners as they need most times lots of instruction to follow the logic of why it's needed.

    Very hard for people to grasp why the gauge only moves less than an inch on the dial and the difference in pounds of 20 or more above 60 enters the danger zone of pressure.

    Here's a page on my site that if I could count the page views, I wouldn't be surprised how many there was. The info is dated so bear in mind the message is correct, the particulars may of changed since its origination.
  15. thank you for the input.....

    Perhaps I worded the original post badly..

    We installed the thermal expansion tank to keep the
    t+p from weeping....
    with incomming pressure at about 85 psi

    wether this will make the heater last longer is debateabe

    although I feel it has to keep stress off the
    heater t+p and plumbing system...
    due to thermal expansion......

    Usually ....I offer the thermal expansion tank AT COST
    when we install a heater.....

    I usually offer a pan too, just to sell the job....its no
    big deal to do........

    When you have a general public that cant even
    flush out their own water heaters once a year,

    its almost impossible to expect them to maintain
    a thermal expansion tank....

    Wether you can get them accept you chargeing them
    a few years down the road to check out their system is
    VERY debateable too....

    We have a company in our town trying to get
    their foot in the door for heater inspections
    and most everyone looks at this as a make work.....

    also people move all the time leaveing the next person
    holding the bag

    Out of curousity Rugged,
    how often should a PRV and Thermal
    exapnsion tank be inspected anyway...???

    and are you actually doing this???

    I am honestly too busy to send out mailers, and
    I dont know how they would be accepted...

    also, its worth at least $175 to go out and
    change one and test the sysetm.....dont you think???

    Rugged....why are you advoiding water heater replacements???
    Last edited: Jan 29, 2008
  16. patrick88

    patrick88 Plumber

    Webster Ma.
    They will not do anything like that. Like I said before I have customers that have no idea were there water main is. If you tell them they need to flush something they will flush the toilet.

    I tell customers they need to have there heater checked and flushed every year and they don't. I have customers that let there septic tanks back up. They all swear it was just pumped last year. It is not worth the breath to tell them anything I hand them any books that come with the item and tell them to read it.
  17. aint it the truth

    Last edited: Jan 29, 2008
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