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Thread: is my HWT good or bad?

  1. #1
    DIY Junior Member Kajun's Avatar
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    Default is my HWT good or bad?

    i have mobile home that has a 30gal "Scott" brand electric hot water heater..the floor was bad under it from water leaking in the bathroom on the other side of the wall from it..i had to remove the tank to change the floor..after i changed the floor i installed it again and everything worked fine.. the next morning i had no hot water.....so i went out and bought a new element. which gave me hot water again.. my buddy said to keep checking it the voltage to the element to see if it is kicking off or not...well everytime i had tested it..power is always going to the element...i decided to change the thermostat and pop off valve while i was messing with it...

    so here i am with all new parts on it except the tank itself...it works fine and i have hot water...whats bothering me is if it is working correctly....my question is...should the voltage be always running to the element? or should it be kicking off when it reaches temp? (set on 120F).....i have checked it many times and it always has voltage going to element....the water is not coming out of the pop off valve...and water temp is not scalding hot when it comes out..its just right...actually i am thinking of turning it up to 130F...its just i can't find a time when there is not voltage running to the element!

    any help or troubleshooting tips on this would be apprecitated..thanks

  2. #2
    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    If it's a 220 heater there is 110 volts going to the element at all times. When the thermostat calls for heat it feeds the 2nd leg on the element and at that point it starts heating.

    John

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    Homeowner Thatguy's Avatar
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    Quote Originally Posted by johnjh2o1 View Post
    If it's a 220 heater there is 110 volts going to the element at all times. When the thermostat calls for heat it feeds the 2nd leg on the element and at that point it starts heating.

    John
    So it runs at 1/4th power continuously to offset the 50w heat loss through the insulation? Does it have a 13 ohm element?
    Last edited by Thatguy; 11-06-2009 at 11:56 AM.

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    DIY Junior Member Kajun's Avatar
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    thanks for the replys...

    here are the specifics from the tag on it...

    state water heater..Scout model 30gl
    model# SCI 30 1HS1 E
    serial# F84142994
    volts: 240 AC only
    element: 350 watts...3500 watts maximum
    mfg by: state industries Inc. Ashland City, TN.


    after reading John's post i tried alil troubleshooting...

    i wanted to see if the 2nd leg would kick in on lower water temp and bring it to 220 V.

    i ran hot water in the shower and kitchen till water was cold... before doing this i was reading 120v at the thermostat and element....after running out all hot water.. it was still reading 120v at the element and thermostat

    at the breaker panel...the HWT is ran on a dual 20A breaker

    any ideas?

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    Homeowner Thatguy's Avatar
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    Quote Originally Posted by Kajun View Post
    any ideas?
    You are not measuring what you think you are measuring.

    With a clamp-on ammeter measure the current through either 20A breaker before and after using hot water.
    Last edited by Thatguy; 11-07-2009 at 07:29 AM.

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    Plumber Cass's Avatar
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    Measure the amp draw at the element not the breaker...you need to check the resistance of the element also...

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    Homeowner Thatguy's Avatar
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    Quote Originally Posted by Cass View Post
    Measure the amp draw at the element not the breaker...you need to check the resistance of the element also...
    Assuming a dedicated CB, the current in all parts of a series circuit is the same.

  8. #8
    Plumber Cass's Avatar
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    You check at the element because you are working at the heater to determine which / if / of the elements are working and it is a lot easier there than running back and fourth to the pannel / CB...and you can switch from top to bottom element from there..

  9. #9
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by Cass View Post
    You check at the element because you are working at the heater to determine which / if / of the elements are working and it is a lot easier there than running back and fourth to the pannel / CB...and you can switch from top to bottom element from there..
    My faith in the measurement capabilities of the OP at the WH has been badly shaken. . .

  10. #10
    Moderator & Master Plumber hj's Avatar
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    Default heater

    quote; So it runs at 1/4th power continuously to offset the 50w heat loss through the insulation? Does it have a 13 ohm element?

    That is neither what was said, nor how it works. You are testing the heater improperly. There is ALWAYS some power to the element from the leg that does not go through the thermostat. Unless you test it properly, you do not know what that power is doing, if anything. You cannot properly test a water heater with a test light, you need a voltmeter/ammeter combination.

  11. #11
    DIY Junior Member Kajun's Avatar
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    i dont have a clamp on ammeter....just a cheap one..can i measure amps with it?.....i have been using the ACV selection..second green one on the right...here is a pic of it....which setting should i put it on to measure amps?


  12. #12
    Retired Defense Industry Engineer jadnashua's Avatar
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    The typical meter (similar to what you have) is limited on the amount of current it can measure...I can't tell from the blurry photo, but I'd be really surprised if it can measure the amount of amps your WH could draw. The socket to the left is probably the one used for this, and it will have an indication of the maximum amperage the meter can handle. The way most end up doing it is with a special probe that attaches to the meter. This could likely cost more than your meter did, but is the easiest way to check current (amperage).

    If you measure voltage across the element, if it isn't drawing any current, it should read zero volts. WHen it is drawing current, it would likely be a couple of volts (would need to know how many ohms the element is to calculate the voltage drop across it).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  13. #13
    DIY Junior Member Kajun's Avatar
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    i'll try to find a clamp on amp meter..

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    Homeowner Thatguy's Avatar
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    You can make your own ammeter [shunt].
    25' of #16 copper wire has 0.1 ohm, so if you hook this in series with the heater and the heater pulls 15A you will read 1.5vac across the length of wire.
    If you don't understand this procedure, don't do it.
    Last edited by Thatguy; 11-07-2009 at 05:02 PM.

  15. #15
    Plumber Cass's Avatar
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    Let him get an amp meter...I know this is a DIY site but lets forget about making our own amp meter...

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