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Thread: Running out of hot water

  1. #1
    DIY Junior Member cari126's Avatar
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    Default Running out of hot water

    We purchased a house about 1 year ago and were running out of hot water, so we replaced the hot water tank. We now have a 50 gallon gas hot water tank. There are two of us living in the house and we use minimal hot water. Every morning we run out of hot water during the second shower (both of us take about a 10 min. shower). We have well water and a water softener. Our water pressure is good. Does anyone have any suggestions as to what to do to try to solve the problem? We are willing to try anything to solve this.

  2. #2
    In the Trades Gary Swart's Avatar
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    This sounds like the dip tube is broken off. There was a problem with dip tubes a number of years ago, but that was a manufacturing goof and was corrected. However, the symptoms sure sound like dip tube. FYI, a dip tube is a plastic tube that fits under the cold water intake and conducts the incoming cold water to the bottom of the tank. The burner is of course at the bottom of the tank and since hot water rises, the entire tank will have hot water. Without the tube, only the top portion of the tank will be hot and therefore you will run out of hot water quickly. It's easy to check the tube, just remove the intake nipple on top of the tank and with your pinky finger find the flared top of the tube. Fish the tube out and see if it is intact. If not, get a new tube, trim the length if it is too long for your tank, replace everything and you should be good to go. If that's not the problem, then I don't have a better guess.

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    Forum Admin, Expert Plumber Terry's Avatar
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    I would replace the shower heads.
    I went to a rental one time with the same experience. The water was just dumping out of the shower head.
    It's an easy fix to run down to the hardware store and pick up a water saver head.
    They will use a common 1/2 IP thread.

  4. #4
    Moderator & Master Plumber hj's Avatar
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    A "10 minute shower" is not a specific term. HOW MUCH water you use during that 10 minutes will determine how long the hot water lasts, and that depends on your shower heads volume control.

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    A shower head can use anything from a gallon/min to lots more. All new ones are required to use 2.5gpm or less, but a shower could contain multiple showerheads. And, on some, you can take the restrictor out or modify it in some other way to exceed that 2.5gpm maximum. 20-minutes could easily drain the tank, depending on what you actually have.

    You can normally only use about 80% or so of the tank before the incoming water cools the output down significantly, so you have 40 gallons to work with. Depending on how hot the thermostat is set, you could be using mostly hot, or only a little. One way to extend the amount of hot water is to raise the thermostat setting. If you go over 120-degrees F, you should also install a tempering valve to bring the outlet back down to 120-degrees. These are required where I live, regardless of the WH thermostat setting, for safety.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6
    In the trades Dana's Avatar
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    If the lower-flow showerhead approach or bumping the temp doesn't get you there, a drainwater heat recovery heat exchanger will with certainty. It's not a cheap fix, but it'll more than double the available showering time, with shorter recovery times for the tank should you ever manage to run it tepid:



    Apples-to-apples performance comparisons between models/manufacturers @2.5gpm flows can be found at

    http://oee.nrcan.gc.ca/residential/personal/retrofit-homes/drain.cfm?attr=4


    It's important that the heat exchanger output feeds both the cold side of the shower and the water heater to get that kind of performance out of it, but it works. In warm-water months a drainwater heat exchanger + gas-fired tank will pretty much keep up with 2.5gpm flows all day & night if you want to.

    It'll reduce the fuel for showering too, but if you're in a low-cost natural gas area the payback in fuel savings can be on the long side (a decade or so.) It's easier to make a financial case for them when the heating fuel is more expensive (propane or higher-priced electricity), but it's not forever even in cheapest-fuel areas if you're showering your way through 50+ gallons daily.

  7. #7
    TROJAN WORLDWIDE SALES RP MACPLUMB 777's Avatar
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    After you get though with every thing else you can fix the problem by changing out the

    cartridge in your single handle faucets to stop cold water bleed over !

    That and the shower heads should fix your problems

    MACPLUMB 777

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    JERRYMAC@TROJANWORLDWIDE.COM


    35 YEAR MASTER PLUMBER, HEATING, ELECTRIC, DRAINS, FIRE SPRINKLERS, WATER HEATER
    AND BOILERS SINCE JAN, 1989

    281-706-1631 7 DYS A WEEK SALES AND TECH. SUPPORT
    Trojan Worldwide Web Site


     



  8. #8
    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by cari126 View Post
    ... we replaced the hot water tank ... Every morning we run out of hot water during the second shower ...
    Check to be sure the heater's cold/in and hot/out connections are not crossed! If your supply is going in where hot water should be coming out, you "hot" is coming from the bottom of the tank via the dip tube that might actually be there.

  9. #9
    TROJAN WORLDWIDE SALES RP MACPLUMB 777's Avatar
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    Good call joe ! ! !

    I have seen this a couple of times over the years even when installed by a licensed plumber

    MACPLUMB 777

    E-MAIL
    JERRYMAC@TROJANWORLDWIDE.COM


    35 YEAR MASTER PLUMBER, HEATING, ELECTRIC, DRAINS, FIRE SPRINKLERS, WATER HEATER
    AND BOILERS SINCE JAN, 1989

    281-706-1631 7 DYS A WEEK SALES AND TECH. SUPPORT
    Trojan Worldwide Web Site


     



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