Opinion on expansion tank installation. Picture included.

Discussion in 'Water Heater Forum, Tanks' started by John Vega, May 23, 2011.

  1. Redwood

    Redwood Master Plumber

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    Oh you mean John Guest fittings.... Big difference from a SharkBite
  2. john guest fittings....huh...

    Wow Redwood....
    I learnt something new today...

    so those are john guest fittings....

    they dont leak but look like pretty much junk..

    except for being plastic, their is really no difference
    between them....

    and they should never be used to be part of the support for a therm tank..



    I wonder how much cheaper they are over a shark bite??
    probably half the price??....
    Last edited: May 27, 2011
  3. Gary Swart

    Gary Swart In the Trades

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    So Plumber Mark, since expansion tanks are just a joke, I should remove mine and just let the T/P spew water each time the water heater operates? Guess the two steel straps from two joists that support the tank are not going to hold the tank if/when it fails and water logs? When (not if) my tank fails, I will know even if I don't inspect it daily. The T/P will trip. Fortunately, my T/P pipe ends at a floor drain so I won't have a flood if I don't see the problem for awhile.
  4. hj

    hj Moderator & Master Plumber Staff Member

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    When a pipe is filled with water, having it in proximity to a heat source will SELDOM cause it to fail. Have you never boiled water in a paper cup over a campfire? ALL water heaters can output overheated water in the event of a malfunction, which can AND WILL backup into the cold water inlet, and THAT is the reason for the copper requirement. You probably DO NOT want to have the expansion tank removed because, in your situation it may be fulfilling a need, but it should be secured properly. The problem with the plumber being the one that does the housing subdivision is that he ONLY has to know what they do every day, NOT the reason for it or sometimes the proper way.
    Last edited: May 27, 2011
  5. if you have a drain......


    A quick question for you...Gary
    did they install a pan..under the new heater?? YES> or NO???
    so in case it ever ruptures and floods the entire home
    before you have a chance to see it leaking...???

    (please take not e of my new avatar)

    we always like to install the heater in a PAN...

    we always try to run the pan and the t+p drain
    off the pressure relief to the nearest drain....or combine them

    A water heater pan IS VERY WISE,
    this keeps me from being blamed for floods years from now
    and a water heater pan is a much better choice over the thermal tank
    if you have a real floor drain near by,,.....



    YES....On occasion the t+p might weep.... depending on the pressure in your home
    and wether you have a prv valve ....... Most times they are piped into a dedicated
    drain and its never a huge issue in the first place......

    if they weep ......its usually once in a baby blue moon,....... if it is going into a DRAIN..
    the odds are you will never even notice an ocassional drip ... "weep" from the pipe.


    If the weeping becomes a problem, simply change the T+P valve and see if
    it remedies itself.... we have done this on occasion for folks that dont want to
    cough up the money for a thermal tank..



    also...if you dont have a floor drain near by,
    we have run the pipes off the t+p to the
    laundry drain pipes

    we have actually poked pipes
    out the side of the homes before to discharge the drain pans
    when they were on slab homes. when no drains were available................




    Now, if the expansion tank breaks off the 3/4 cpvc pipe when
    it gets heavy and water logged years from now ....
    there will certainly be a huge , massive......flood.. spraying everywhwere.

    please weigh your options yourself....
    and you do whatever you think is best

    I dont really want to get into a huge
    debate about this .....especially with a bunch of people
    that dont do this for a living..
    and dont know what they are talking about.

    ...
    Last edited: May 28, 2011
  6. hj

    hj Moderator & Master Plumber Staff Member

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    quote; or combine them

    SELDOM, if ever, a good idea, unless they are joined RIGHT AT the drain outlet. Otherwise the T&P WILL backflow into the pan and overflow it. And as for "But Florida Code does allow the direct connection to the water heater... ", that is a good example of a code that is a minimum standard rather than a professional way to do it.
    Last edited: May 28, 2011
  7. SteveW

    SteveW DIY Senior Member

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    MPM says:
    "did they install a pan..under the new heater?? YES> or NO???
    so in case it ever ruptures and floods the entire home
    before you have a chance to see it leaking...???"
    **********************************************

    I'm not a pro, but --

    looking at the Watts site mentioned above, it seems to suggest that a thermal expansion tank might actually PREVENT a WH from rupturing - this seems plausible to me that if a home has thermal expansion problems that are not corrected, it could certainly stress the WH tank (that extra 1/2 gallon of "expanded" water has to go SOMEWHERE) and cause cracks in the lining, etc.

    So - under certain circumstances, it appears that having some sort of thermal expansion relief (expansion tank or other mechanical device like the Watts pressure-relief ballcock, etc.) could potentially make it less likely for a WH to rupture.

    Do you pros buy this? Again, from a homeowner's perspective it seems reasonable to me. I have observed in my own home that my water softener (a dreaded Kenmore) has functioned much better with longer intervals to replace rotors since I have put in an expansion tank, so it seems to me that other pressure-sensitive parts of the plumbing system could have longer lifespans with proper relief of thermal expansion issues.
  8. combineing them


    normally we install the heater on bricks
    in the pan....

    we usually will run the t+p valve down into the pan ,
    then run the pan drain over to the floor drain... or run the t+p
    over to the drain, depending on the situation.

    but :cool:I have made that mistake before......
  9. they have an interest in selling them



    Watts sells expansion tanks for a profit and a living and have a vested interest in telling the public that you cant live without them....... but yes you can....

    Their are literally a hundred million homes without them in this country that have worked perfectly fine for decades and decades... and now all of a sudden the world is going to come to an end if one is not installed on your system..

    In this city alone their are literally tens of thousands of water heaters installed on the second floors of the homes without thermal expansion tanks.... all built around 1995..and after to this date..

    those plumbers ignored the thermal tanks but did install alluminum pans and piped the pan and the t+p line to the flooor drains in the room... they have mostly all worked fine till the heaters started leaking.....


    if you have dramatically high pressure you should consider one,, and also a PRV valve to kick it down to 70psi...



    Sometimes I have wondered which congressmen watts had to bribe to make thermal expansion tanks code...:cool:

    If you are not willing to service the system yourself, its just a matter of time
    before that Expansion tank becomes a liability when it gets waterlogged....

    also, those Watts pressure releif ballcocks scare the dickens
    out of me and I wont trust them...



    this is what a water heater looks like after 10 years of service in Indiana
    with no one ever flushing it out.....
    http://www.youtube.com/v/mjWDyaQGDiY&hl=en_US&feature=player_embedded&version=3%22%3E%3C/param%3E%3Cparam


    [video=youtube;mjWDyaQGDiY]http://www.youtube.com/watch?v=mjWDyaQGDiY&feature=player_embedded[/video]
    Last edited by a moderator: May 28, 2011
  10. SteveW

    SteveW DIY Senior Member

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    Yikes - that's a nasty collection of hard-water minerals! I never thought about it before this, but I guess that the heat from the WH does something to the calcium and magnesium in the water to make them settle out?

    Going back to the point that residential plumbing systems have survived without expansion tanks for many years - yes, true - my parents house never had on one and didn't seem to need it. The two houses I've owned have both had thermal expansion problems, though. Are PRVs being used more than they used to? Or are PRVs now made with check valves, and they didn't used to be?

    Sounds like something has changed.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If you don't have a closed system, you don't need an expansion tank. Many homes have an open system, so any expansion has free access to the whole supply system - you'd never see a pressure increase as it would dispurse throughout the entire system feeding your house and neighborhood. BUT, exactly for that reason that water could get pushed back into the supply from a house, and it could have gotten polluted in the house, many locations are now routinely installing a check valve in or at the water meter turning those once open systems into closed systems. So, you could have been living there for decades with no problems, the utility company does some 'routine' work on your meter, and now suddenly you have a closed system, and things leak because of the expansion and resulting pressure increase. If you have a leaky valve (say a toilet valve or anything that drips a little), that may be large enough to relieve any pressure buildup. But, if you're good about maintenance and don't have any leaks, since water doesn't for all practical purposes compress, it will expand and create increased pressure. This will often trip the T&P valve at the WH. But, it might just burst a weak supply hose to the toilet, washing machine, or a sink. That's the thing...those items are not designed to be stressed by high pressure on a periodic basis...an expansion tank is.

    So, while you may get along quite fine without one, the circumstances could change quickly, and you need one.
  12. SteveW

    SteveW DIY Senior Member

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    Yep, get the part about open vs closed systems.

    The question is still: why does it seem like now (like the last 10 years?) there is more of a concern about thermal expansion?

    I never heard anything about this 10 years ago. Was it happening but people didn't recognize it?

    Or has something changed, like more check valves being used? Or water companies using higher pressures, leading to more of us needing PRVs?
  13. ballvalve

    ballvalve General Engineering Contractor

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    thanks, I have been saying that here for a long time. Funny that redwood did not attack you for being low on grey matter for speaking the truth about this.

    And all toilet valves are pressure relief valves around 160 psi!

    And the utube is a POS saying the heater needs replacement each 6 years. It needs MAINITENANCE every year.

    Dont change your engine oil and just trade it in every 5 years would work too.
    Last edited: May 28, 2011
  14. Redwood

    Redwood Master Plumber

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    Anyone that would think it is okay for a T&P Valve to dribble relieving the pressure from thermal expansion is either in the business of selling water heaters and wanting to increase his sales due to early failure of the water heater from metal fatigue and cracking of the glass lining increasing corrosion or short of the grey matter!

    That's my story and I'm sticking to it!

    I think the reasoning is sound in both cases.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Many utilities are now installing check valves when retrofitting meters and on new installations. As areas are being built-up, to provide decent water pressure to all of the customers, many utilities are adding pumps, towers, and raising the pressures. This means more PRV's are being installed. So, yes, you could have lived there for decades with no problems...things change, you change with it, or suffer the consequences. Just because you've 'always' done it one way, does not mean that it necessarily still works and is the best way. Change with the times, or suffer the consequences...if you have a closed system, the accepted solution is an expansion tank. Live with it.
  16. SteveW

    SteveW DIY Senior Member

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    Omaha, NE
    Again, I am on the same page as you - I am not arguing; I insisted on having an expansion tank put in when my WHs were replaced, even though several local plumbers seemed to think I was crazy.

    I heart expansion tanks!

    Just wondering why now the awareness of this problem. Your explanation makes sense to me - expanding neighborhoods, higher water pressures, and water companies that are using more check valves to prevent contamination.

    Makes sense to me.
  17. 6 years is a little short....

    actually , my buddy from DUNBAR PLUMBING made that video for me....

    and me and my buddy REDWOOD disagree all the time,,,,
    I dont take it personal...

    I would have probably stated 7 or 8 years between change outs..

    Yes , I do have a vested interest in installing water heaters....

    and I am going out right not at 8 pm to install a
    50 galllon PRO RHEEM.......

    and I am gonna install it in a pan,
    and I am gonna run the drain to the sump pump...
    and I will offer them a thermal expansion tank for another $150 dollars, but they will probably decline my offer becasue it
    sits right by the sump pit....

    and you dont want to know what I am chargeing them tonight....

    so talley---ho..........up, up and away I go.....

    .

  18. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    quote; So - under certain circumstances, it appears that having some sort of thermal expansion relief (expansion tank or other mechanical device like the Watts pressure-relief ballcock, etc.) could potentially make it less likely for a WH to rupture.

    EVERY water heater MUST have an approved temperature AND PRESSURE relief valve, so a "thermal expansion relief valve" would be redundant. They release at a "safe" 150 psi,, but if you do NOT wish to install an expansion tank, you CAN install ANY pressure only relief valve somewhere in the system with a set point equal to your desired maximum pressure and it will discharge any time the pressure rises to the point. Which is EXACTLY what Watts "TERV" does.

    quote; And all toilet valves are pressure relief valves around 160 psi!

    Absolutely NOT true, and if the heater's T&P valve is functioning properly , HOW would the pressure get to 160 psi anyway?
    Last edited: May 29, 2011
  19. LLigetfa

    LLigetfa DIYer, not in the trades

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    ...in theory, as long as they still work. When I took out my 10 year old tank, I tried releasing the TPR to break the vacuum and it was seized shut.

    Now, my system is not closed so any expansion would be absorbed by my iron filter precipitation tank so the only real risk was of a runaway flame boiling the water in the tank.

    My RO filter could also absorb some of the expansion.
  20. Redwood

    Redwood Master Plumber

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    This link is a post that discusses pressurization cycles on a pressure vessel, and metal fatigue caused failure. Incidentally it is also in a thread muddied up with the rambling thoughts of a thick headed engineer...

    These engineers come and go but for each one that goes, we always seem to get another willing volunteer to take his place muddying up threads with their senseless wisdom....

    It is a "Strange Day Indeed" when plumbers start agreeing with their senseless ramblings....

    Pressure Cycling on pressure vessels is real and it does cause fatigue of the metal. Sooner or later the metal cracking or the damage to the glass lining from this flexing allowing corrosion damage to occur will cause a failure of the tank. An expansion tank will hold the pressure constant vs. the relief allowing it to fluctuate between the supplied pressure and the rated opening pressure of the valve. In the case of relying on the T&P as Master Mark suggests is okay this could make the minimum pressure cycle to be 70 PSI. Incidentally the pressure cycle on a jet airliner taking off at sea level and going to it's cruise altitude at 30,000' is only a 10.34 psi cycle and we can see the consequences in the linked thread.

    It's plain and simple Expansion Tanks Work!

    Instead of the tank going through pressure cycles and being subjected to metal fatigue and an early failure, the tank pressure remains constant. A relief valve can work, we have been through this discussion with BallValve, however it is not the best choice. An increase in pressure supplied or a failure of the valve can lead to a very high water bill without you ever knowing the water was flowing down the drain. These valves do not last forever, and someone is placing way too much value in a $50 valve over a $50 expansion tank. Even with a relief valve as proposed by our esteemed engineer friend a water supply system that has a supplied pressure of 40 psi would go through a minimum of a 35 psi pressurization cycle to the opening pressure of the relief ball valve with every heating cycle, incurring the metal fatigue and shortening its service life. Neither device protects against runaway heating, that is the job of the BTU rated T&P valve. With the price being equal and one having the ability to waste large volumes of water while subjecting the water heater to life shortening pressure cycles, it is like a no-brainer to me but that doesn't always work with engineers.

    The use of the Governor 80 Ballcock is remote from the water heater and is easily isolated out of the equation with shut off valves leaving no protection. In addition someone doing toilet repairs can easily not know what they have and replace this uncommon ballcock with a Fluidmaster 400A removing what little protection it afforded. We've been through that argument as well. There are many ballcocks that will not open at 160 psi as our esteemed engineer believes in his senseless ramblings above...

    Simply stated a properly installed Thermal Expansion Tank is the best available solution for thermal expansion.
    Last edited: May 29, 2011
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