Hot water doesn't last

Discussion in 'Water Heater Forum, Tanks' started by bajaboy1, Nov 13, 2012.

  1. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    I know this question has been asked many times, but the solutions haven't helped me as of yet.
    Culprit: 2001 AO Smith gas 40 gallon water heater.
    Problem: Hot water only lasts about 10 gallons. Luke warm after 11 and getting cold at 12.

    I've cleaned the tank.
    I've replaced the dip tube (which was fine).
    I buttoned up the air so I have no leaks, have a nice blue flame.

    Any advise appreciated.
    Last edited: Nov 13, 2012
  2. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    To add.
    Water heater turns back on after 5 gallons used.
    Thanks
  3. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,897
    Location:
    NW Ontario, Canada
    That puts it at 11 years old. Maybe it looks like this on the inside.

    [​IMG]
  4. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    I suppose it could! I've flushed it since new a few times a year though.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    Last guy that had this problem found a leak in the pipes under the house. It doesn't take much to minimize the hot water available. Do you get warm water at any other faucets in the house? A defective faucet that's creating a cross-over can limit the amount of hot water available, too.
  6. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    No leaks anywhere. It happens at any shower or faucet in the house. Should the water heater turn on sooner?
    Last edited: Nov 14, 2012
  7. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    Could the temp probe be scaled up or bad causing issues? Only thing I haven't checked or changed.
    Last edited: Nov 14, 2012
  8. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,328
    Location:
    Yakima WA
    While just replacing things on the chance that that piece/part might be the problem isn't a very sound method, in this case, an 11 year old water heater is likely about served out its life anyway. The A O Smith is not a favorite heater among the plumbers on this forum, so that might also be a good reason the get a new heater. If that doesn't fix the problem, then of course you'll have to look elsewhere, but the heat is really about due anyway.
  9. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    I thought they were good till they start leaking, rusting out. What else goes bad on the inside to prevent heating up? And thanks all.
    And what brand do you recommend?
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,897
    Location:
    NW Ontario, Canada
    Did you not see the pic I posted?
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    Mineral deposits can deplete the volume and act like a big insulator. The 'average' WH probably only lasts 6-8 years. Yes, some can last much longer than that, but for practical purposes, at 11, if it's not working properly, it probably isn't worth mucking with. FWIW, often, the only difference in a longer warranty is (maybe) a better sacrificial anode and the warranty...it's often the same tank, you're only paying the insurance betting it won't last that long.
  12. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    See the pic.Didn't think that was "normal" when you take care of it.
    So I need a new one. Mine has the power vent on it, no chimney. I suppose this is just a regular water heater with the power vent, correct? Can be reused on another heater?
    Thanks again
    Last edited: Nov 16, 2012
  13. DonL

    DonL Out of the Trades

    Messages:
    3,909
    Location:
    Houston, TX
    If the water comes out Hot in the first place then it must be heating.

    The mixing of cold coming in to hot going out will affect the Output Temperature.

    The gas will not heat the water as fast as you can use it with Hot wide open.

    Most people add some cold water to the hot and can take a normal shower.

    If your recovery is slow, than that is a different problem.

    Maybe your thermocouple is out of gas.

    May be time for a new heater.
  14. wassermeister

    wassermeister New Member

    Messages:
    24
    Location:
    portland, OR
    It may not be your water heater after all that's causing the issues. What are your water pipes made of? If you have galvanized pipes or are using well water you may have junk in the pipes that restrict proper flow.
  15. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Oh NO NO NO! A power vent water heater is built and UL listed as such. It will cost you more. NEVER attempt to modify a WH in any way.,
  16. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    Yes, have since found that out. Thanks. Looks like I may go electric since I have that option. Can't see spending $1000 on a power vented.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,892
    Location:
    New England
    Kentucky might have access to fairly cheap TVA power, but in most places, a gas WH is 1/3 or so of the cost to heat water verses electric, so factor that into your expected payback analysis.
  18. bajaboy1

    bajaboy1 New Member

    Messages:
    9
    Location:
    KY
    Yep, need to look at that.
    Thanks
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