Warm water runs out quickly

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Mad Plumber, Apr 24, 2009.

  1. Mad Plumber

    Mad Plumber Mad Skills

    Messages:
    222
    When I first turn on my cold water in the
    morning it comes out very warm and after 15 to 30 seconds it gets
    cold. My thermostats are set 140 for the top and 142 for the
    bottom. I have a well and the pump is set to come on at 40 lbs and
    cut out at 60 lbs and my pressure tank has 38 lbs of air. I also
    run out of hot water if I take a 12 minute shower. It did not used to
    run out that soon. I replaced the cal rods in the tank and checked
    the fill pipe. (It goes almost to the bottom of the tank). I have a 40gal tank with electric heat. . There is no sediment in the tank. I am 83 years old and am a retired dentist and have done all
    my own plumbing and electrical for 50 years. I am stumped. HELP!!!
    Ralph M
  2. leejosepho

    leejosepho DIY scratch-pad engineer

    Convection might be warming the supply line above the water heater.

    Maybe those thermostats have become weak and your water is not actually that warm when they shut off.
  3. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Hi Ralph,
    There are a few possibilities.

    1 Do you have a hot water recirculation system?
    These are to assure that hot water is right at the tap without waiting for it.
    Sometimes if a check valve fails in these systems cold water can feed up the recirculation line and cause this.

    2 Do you have single handle faucets installed either Mixet or, Moen brand?
    Some of these when they fail can create a hot/cold cross connection and still appear to work.

    3 Have you had any plumbing work done that is unfinished I.E. Delta R-10000 universal valve without the cartridge installed. This is a common hot/cold cross connection.

    4 Do you have any fixtures anywhere where the hot and cold may be turned on together but the outlet can be shut off?

    5 When was your water heater installed? in the 90's many water heaters were sold with defective dip tubes. Click here for information on defective diptubes includin serial numbers of affected units

    6 Check the upper and lower elements and T-Stats of your water heater to make sure they are operating okay.

    7 If you have a tempering valve on the output of the water heater make sure it is operating properly.

    [​IMG]

    Hope this helps you out.
    Last edited by a moderator: Aug 6, 2011
  4. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    I WOULD FOLLOW REDWOODS POST ! !

    9 TIMES OUT OF 10 IT'S A BAD LOWER ELEMENT. ie. IF THE UPPER ONES IS OUT THEN YOU HAVE NO HOT WATER, IF JUST THE LOWER ELEMENT IS OUT THEN YOU ARE ONLY HEATING THE TOP HALF OF THE TANK. IN OTHER WORDS ONLY 20 GALS. OF HOT WATER

    THE OTHER 1 TIME IS LIKE REDWOOD SAID YOU HAVE A BAD CARTRIDGE IN A FAUCET,

    THEN CHECK THE OTHER THINGS
  5. kordts

    kordts In the Trades

    Messages:
    551
    Location:
    exurban Chicago
    12 minutes times 2.5 gpm = 30 gallons of hot water. That's about right. His showerhead might be an older one that doesn't restrict to 2.5.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,874
    Location:
    Cave Creek, Arizona
    water

    We do not have enough information. Is this a house with a slab floor? Both problems can be caused by a cracked hot water line under a concrete slab. Otherwise, and possibly even then, we would have to be there to see what could be causing the problem.
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