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Thread: HW tanks

  1. #1

    Default HW tanks

    I have an older hw heater 34000 btu 40gal. My question is lack of hot water. I have it fully opened and seem to run out of hot water after 15min shower. Its centrally located in bsmt between kt,mbd. Its also a gas heater if that makes a differance. Any ideas on what I can do to either mod,check or fix to get the desired performance. Will a higher btu take care of that? I have considered installing another hw heater in parall. I think series would not work as well and still have the heating problem.


    Ps. This house was built in the 70s and as to my knowledge no water restrictions are on the shower heads. If that makes a differance. I hate to give up my high flow heads to have a longer shower.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Suggestion...take a bucket and a watch with a secondhand. Measure how much water comes out of the showerhead when adjusted the way you want. A minute or two should be enough. Then you can figure out how big of a water heater you really need.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Plumber Cass's Avatar
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    Quote Originally Posted by Duane Smith
    I have an older hw heater 34000 btu 40gal. My question is lack of hot water. I have it fully opened and seem to run out of hot water after 15min shower. Its centrally located in bsmt between kt,mbd. Its also a gas heater if that makes a differance. Any ideas on what I can do to either mod,check or fix to get the desired performance. Will a higher btu take care of that? I have considered installing another hw heater in parall. I think series would not work as well and still have the heating problem.


    Ps. This house was built in the 70s and as to my knowledge no water restrictions are on the shower heads. If that makes a differance. I hate to give up my high flow heads to have a longer shower.
    You may have a bad dip tube.

    Remove the cold side nipple coming out of the top of the heater and you can then pull up the dip tube and see if it is still in one peice around 36" or so long.

    Don't burn your self.

    They sell new ones(dip tubes) at the big box stores

    Is this something that just started happining?

    You might have a burnt out element if it recovers slower than it used to.
    Last edited by Cass; 01-28-2006 at 04:18 AM.

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
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    SHowerheads (new ones anyway) use about 2.5 gallons per minute, so a 15-minute shower would use 37.5 gallons. Unless you HWH is set very low, then you'd mix that with some cold water, but keep in mind that the hot water you started with is being mixed with cold water to replace it and cool the whole thing off. Obviously, the heater is running during this trying to heat it back up again.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default shower

    15 minutes is a long shower and no 40 gallon water heater would keep up with it. And since most heaters, until you get into the very large sizes, have essentially the same btu input, and thus dynamic recovery rate, all you will gain by installing a larger heater, 50 gallon for example, is the extra 10 gallons of use, which would probably be about 3 minutes, depending on the shower head capacity.

  6. #6
    In the Trades Bob NH's Avatar
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    "I have considered installing another hw heater in parall. I think series would not work as well and still have the heating problem."

    Series might work better than parallel. With parallel you to balance the flows which could be done with careful piping and valves but is hard to do without water meters. You could run out of hot water in one before the other.

    If you put a 50 gallon heater in series with the 40 gallon heater you will more than double the storage and will double the recovery rate because when you start running water the first heater will come on and warm up the supply to the second heater.

  7. #7
    Plumber jimbo's Avatar
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    The delivery of a WH is 70% of size, so you can only get 28 gallons of water hot enough to shower in. This will NOT give you a 15 minute shower.

    If you must have Hollywood showers, I suggest 60 gallon High Output tank.

  8. #8
    Master Plumber master plumber mark's Avatar
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    Talking 50 gallon

    you got two choices.....

    either stop playing with your bar of soap so long

    or install a 50 gallon

  9. #9

    Default

    I picked up a dip tube and will pull the other one out to see if it still in good shape.


    I like my bar of soap thank you.



    Ps. If I was to install a 50gal should I get a energy effecient or just the plane jane type. I guess will I see a reduction in my gas bill to warrent the cost?

    Pss. Not as easy a process as I had hoped. Whose crazy idea is it hw should be placed on stands?
    Last edited by Duane Smith; 01-28-2006 at 12:39 PM.

  10. #10
    Plumber jimbo's Avatar
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    WH in garages were required to be elevated so that the pilot would not ignite the fumes from small gasoline leaks.

    All WH 50 gallon or less are now FVIR ( flammable vabor ignition resistant). Many localities have updated their code to allow this type of WH to sit at floor level even in the garage. Check to see if this is allowed in your area.

  11. #11
    Moderator & Master Plumber hj's Avatar
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    Default heater

    If you install a 50 gallon heater to get more water, and then get an energy efficient one to use less gas, which will also mean less hot water, what have you gained.

  12. #12
    Plumber/Gasfitter dubldare's Avatar
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    15 minutes is a long shower and no 40 gallon water heater would keep up with it.

    My 40 gallon electric keeps up with me and my wife, and our long showers. Although, I run ~145.

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