Water Heater wiring, Please help

Discussion in 'Water Heater Forum, Tanks' started by Pastorar, Feb 22, 2015.

  1. Pastorar

    Pastorar New Member

    Joined:
    Feb 22, 2015
    Location:
    Florida
    First and foremost thanks for your help. I've changed both the tstats and elements on my tank and now I've changed the top Tstat twice because I thought the new one was defective. I'm getting a reading from the wires that come from the wall of 240v but when I hook it up to the tanks junction box I get a reading of zero. I do get a reading of 120v when I touch the red and tank. The reading on the 1 & 3 terminal also reads zero but from either one to ground I get a 120v reading. Why is this?
     
  2. JerryR

    JerryR Active Member

    Joined:
    Jul 27, 2011
    Location:
    Florida
    First, BE VERY CAREFUL WHEN MEASURING SO YOU DON'T ELECTROCUTE YOURSELF

    If your not experienced or comfortable working with a meter or around high voltage get a pro to do this.

    You didn't say what is happening with the heater. Is it not heating up at all?

    If your not getting any hot water and you have 240 v at the source, then the likely cause is either an open top element or a defective top thermostat.

    --------

    Here's what I would do to check out a heater after confirming I have 240 v at the top theremostat.

    1- disconnect the heater completely from electric by throwing the 240 v breaker.

    2- take resistance measurements across both elements to make sure they are not open. If the top element is open you will never get any hot water.

    3- if you read good resistance across the top element then turn power back on and CAREFULLY measure the voltage across the top element. You should get about 240 volts. If you don't get 240 v across it then the top thermostat is suspect.

    Note: don't be fooled. One leg of each heating element will always read 120 v to ground. The other leg is switched to opposite 120 v phase when active.
     
    Last edited: Feb 22, 2015
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  4. JerryR

    JerryR Active Member

    Joined:
    Jul 27, 2011
    Location:
    Florida
  5. hj

    hj Master Plumber

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    quote; . I'm getting a reading from the wires that come from the wall of 240v but when I hook it up to the tanks junction box I get a reading of zero.
    IF the same wires that have 240 when they are "open" do NOT have any voltage when you connect the heater to them then you have a problem at the circuit breakers. You should always get 120 v from the elements to the tank, unless the tank's ground has been disconnected. It is hen you get 120v between the terminals on the element that you have a problem.
     
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