tub is lower hot water temp., than what is set@ WH thermostat

Discussion in 'Water Heater Forum, Tanks' started by bikeboy, Oct 11, 2019 at 8:59 PM.

  1. bikeboy

    bikeboy New Member

    Joined:
    Apr 18, 2019
    Location:
    Toms river New Jersey
    Hot water @whirlpool tub spicket reads 90 deg. , when 50 gallon electric water heater elements are both set @ 120 deg. ; and tub spicket is 110 deg. , when water heater therm. is set @140. Both Thermostats shut-off their elements , and both test with good continuity, no short to ground nor an open. Before I add another water heater, i'd like to have an opinion what could be wrong.,

    Thank you;

    Howie...
     
  2. WorthFlorida

    WorthFlorida Black Belly Whistling Ducks

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    Those tiny little dials with the set screw are not that accurate. Test the water temp at the faucet closest to the WH. Slowly turn up each thermostat, allow time for the water to heat up, maybe twenty minutes, and check the temp. I once had to move the dial to about 129 to get 120 degree water.

    These thermostats sit on top of the steel tank, they are are not immersed in water. As you run water, some heat is lost through the pipes. Ambient room temperature of the water heater can affect the set point temperature.

    Depending on the age, these thermostats do go out of calibration and they are easy and cheap to replace. It is also possible that one of your heating elements is out and you are running the water before it can reach temperature. Hard to say with the limited information we have.

    Do you know your tub/shower valve body is?
     
    Last edited: Oct 11, 2019 at 10:01 PM
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  4. bikeboy

    bikeboy New Member

    Joined:
    Apr 18, 2019
    Location:
    Toms river New Jersey

    The valve body is of a Delta whirlpool type with separate diverters. There seems to quite a differential between the two points . The water heater is only a few feet away from the tub. The elements are drawing 4.5 kw each, and switch over as needed. I am able to barely make a fill in the summer months, but I doubt it would in winter. there's probably quite a temp drop in the ground water. city water hookup long distance to street, and shallow (Tennessee). I thought of a tempering tank (another heater) ahead for cold months. I have a second water heater opposite side of house, and trying to figure a way to tap it to that tub line (combine flows) w/o a circulator.


    HR....
     
  5. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
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    Retired
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    NW Ontario, Canada
    A single handle tub filler is unlikely to deliver 100% hot water as it will blend in a little bit of cold water even when turned all the way over to hot. Some valves have a setting inside to control the upper limit.
     
  6. bikeboy

    bikeboy New Member

    Joined:
    Apr 18, 2019
    Location:
    Toms river New Jersey
    There are separate hot and cold valves with a single spout.
    HR...
     
  7. dj2

    dj2 In the Trades

    Joined:
    Aug 13, 2013
    Location:
    California
    WorthFlorida gave you the answer: the thermostats are not that accurate.
    Similarly, you oven temp is not that accurate.
    If you want your water hotter, raise the thermostat knobs up to the desired temp. But why do you want 140 degrees?
     
  8. bikeboy

    bikeboy New Member

    Joined:
    Apr 18, 2019
    Location:
    Toms river New Jersey
    I'm trying to get at least 105-110deg at the tubs hot side, then I can mix cold in. Therm. set @140 gets me 110deg. in summer. Since the WH is only a 50 gall. , the tanks capacity is at it's threshold for that given temp. I'd rather not go higher, tried it once , and in the winter , the colder incoming water wouldn't allow the therm. to shut the upper element off, and couldn't fill tub. HR...
     
  9. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
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    Retired
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    Could it be reseated to make better contact with the tank wall? How about adding a little thermal grease as is used on computer CPU heatsinks?
     
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Retired
    Location:
    NW Ontario, Canada
    Something else must be wrong then. The incoming water is supposed to be directed to the bottom of the tank. Maybe that tube has disintegrated? That is a known issue with some tanks.

    A tempering valve installed at the tank outlet is a safer way to get more capacity from a HWT by reducing scalding risk.
     
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