Water just warm, not hot

Discussion in 'Water Heater Forum, Tanks' started by higgledy, Oct 29, 2012.

  1. higgledy

    higgledy Member

    Messages:
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    Location:
    21701
    I need some advice with my water heater, it is a 5 year old Sears Power Miser 12, which I think are made by State. It only heats the water to warm, at best. I checked both elements with an ohm meter and visually. Both measured about 12 and 15 ohms across their terminals and both looked good, too.

    I tested the thermostats per the instructions on this page, http://www.water-heater-repair-guide.com/hotwaterheaterthermostat.html

    The one thing that did not checkout was I got 0 volts across the lower element terminal thats with the upper thermostat set to the coldest setting, and the lower thermostat set to its hottest setting. That should have kicked power to the lower element. Correct?

    I then replaced the upper thermostat, but same thing. I want to replace the lower thermostat but I can't find an exact match. Does the replacement thermostat need to match the top exactly? Or can I use a different brand, but same volt/watt/current rating.


    Sorry for the long winded post. Thanks for any replies.
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,118
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    Bothell, Washington
    The upper thermostat puts power to the upper element first. If the upper is burned out, there will be no heat.

    The lower only comes on, only if the upper has been satisfied. So you can wind up with less hot water if only the upper is working.

    You would normally set both thermostats for the same temperature.
  3. hj

    hj Moderator & Master Plumber Staff Member

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    It is easy enough to tell if the lower thermostat is the problem. Check for power between its two terminals. If it is ZERO the thermostat should be okay, if it is 220/240 then it is open, and there may be a problem with it depending on the water temperature. There are only four test that have to be made;
    1. Does the upper thermostat have power, and if not, why not
    2. Is there power to the upper element and if so is it being used
    3. Is there power to the lower element and if so is it being used
    4. Is the lower thermostat functioning properly

    The lowest setting on the upper thermostat does not necessarily active the lower element. it depends on the water temperature. I NEVER test elements with an ohmeter.
  4. higgledy

    higgledy Member

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    Location:
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    Thanks. This afternoon I replaced the upper element. Now, both elements are new.

    How long would you expect to have hot water after filling the tank? It's been powered for two hours and all I have is tepid water at the tap. Yes, I did fill the tank and run a hot tap for several minutes before applying power. Thanks.

    If it does not get hot tonight, I'm calling a professional tomorrow.
    Last edited: Oct 30, 2012
  5. higgledy

    higgledy Member

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    Location:
    21701
    Which two terminals? i am measuring zero vac across the lower element. This is while the upper element has 240vac. From what you guys say, this is correct.

    Is it ok if I replaced the upper element with high watt density rated at 3800W? The original was a 3800W low watt density (folded) element. None of my local stores had a LWD element at 3800 watts...not even one at 3500 watts. Thanks
  6. higgledy

    higgledy Member

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    Location:
    21701
    I hired a licensed plumber to fix my water heater. He replaced both thermostats and both elements and I still am only getting warm water. Does anyone have any ideas what else might cause just warm water? It's not that I get hot water and then it goes cold. It's just warm all the time. Thanks.
  7. Terry

    Terry Administrator Staff Member

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    Is this in a home, or an apartment building?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    Are you getting the same on all taps in the house? Have you tried seeing how hot the water is from the WH drain line? Do you have a recirculation system? A recirculation system would have a check valve, and that may have failed, allowing cold, or less hot water get to your valves. Water will take the path of least resistance.

    A faulty shower or sink valve can allow the hot to mix with the cold, giving you tepid water in many places. But, first, you need to test the water temp out of the tank. If that's hot, then you have a problem elsewhere. If not, it's either the tank or its input power. A CB that is failing could limit the power to the tank. A bad wiring connection could limit the power to the tank. This is why an ammeter is useful...it measures how much current the line is carrying, and not the potential.
  9. LLigetfa

    LLigetfa DIYer, not in the trades

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    Maybe the pipe goes under a slab and you have a leak. The water heater may not be able to keep up with the demand.
  10. higgledy

    higgledy Member

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    Location:
    21701
    This is in a home. There is no circulation pump involved. There are no pipes other than drains running under the slab.

    The plumber, whom I've hired before, he's always done good, neat work for me. He knows what he is doing. He says he cannot find the problem. The tank is clean, dip tube fine. Internal wiring checks out fine. Voltage at the WH is correct, running 10AWG on 30Amp circuit---circuit breaker is fine, too. It's just the bottom element never gets energized. i.e. the top element is never satisfied.

    Water drawn from the WH drain is cold--like straight from the tap cold. Water drawn from the TP valve is warm.

    My plumber called my wife last night and told us he is baffled by our WH. He says that in his 25 years, it is the first WH he has not been able to fix or figure out why it is not working.

    BTW, my water heater is seven years old, not five years old as I originally stated. I counted wrong. :\

    Any ideas?
  11. higgledy

    higgledy Member

    Messages:
    45
    Location:
    21701
    Water temp at the WH is cold from the WH drain and tepid-warm at the TPV, same as I am getting at the tap.

    It is not the CB because the top element is working and the plumber measure 18+amp draw while in operation. I am thinking an 18amp load would be enough to energize the bottom element or at least show a faulty CB.
    Last edited: Nov 3, 2012
  12. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,052
    Location:
    NW Ontario, Canada
    It still sounds like hot water is being consumed faster than the heater can reheat it. Even with just the top element heating, you should get hot water, just less of it. Are you 100% certain that there isn't a continuous draw on the hot water? Check the water meter when there is no water usage.
  13. higgledy

    higgledy Member

    Messages:
    45
    Location:
    21701
    But even if there was a water draw wouldn't the bottom element kick-on at some point? Plus, if it drawing enough water that the water heater could not keep up, wouldn't I hear water running in the house? Like the noise you hear when the garden hose is running. To play it safe, I am at work now, but I'll check the water meter when I get home tonight and get back to you.
  14. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,052
    Location:
    NW Ontario, Canada
    I have had gas water heaters for nearly two decades now so have not needed to stay abreast of the technology used on electric water heaters. That said, I doubt the technology has changed.

    An electric HWT with a bad bottom element basically gives you the same temperature water, just less of it. The water stratifies... hot rising, cold settling on the bottom.

    An electric HWT with a broken dip tube can cause the stratified hot water at the top to blend with the incoming cold affecting the temperature.

    In some code jurisdictions, a tempering valve is required after the HWT, the purpose of which is to blend in some cold water if the temperature is above a preset. One would assume a plumber worth his salt would recognize and know how to diagnose a bad tempering valve, but I'll throw this out here JIC it was overlooked.
  15. higgledy

    higgledy Member

    Messages:
    45
    Location:
    21701
    The plumber pulled the dip tube, it is intact. The bottom element is not bad, it never gets power --the top element never gets satisfied. There is no tempering valve in my system, it is not code in my area.

    You are lucky to have a gas water heater. If I had natural gas in my neighborhood, I'd dump electric in a second.

    Here is a link to a water heater problem nearly exactly like mine. He's final solution was to replace the water heater.

    http://www.justanswer.com/hvac/1wuru-lower-element-electric-hot-water-heater-does-not-on.html
    Last edited: Nov 3, 2012
  16. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,129
    Location:
    New England
    You might not hear water running from a leak, if there is one.

    The top element comes on first so you have hot next the top/exit point. Once that upper volume is hot, it switches to the bottom element which will continue until it heats the rest of the WH tank, then it shuts off, too. If the top element can't reach its setpoint, the bottom element won't ever turn on, but, you should have a small volume of hot water at the top if the top element is actually drawing those 18A and there's no constant flow. A constant flow will result in the WH never getting up to temp if it is high enough volume (doesn't actually need much).
  17. higgledy

    higgledy Member

    Messages:
    45
    Location:
    21701
    Jadnashua, you were right. I found a broken pipe in the crawl space. I have not got in there yet, but it must be a pin hole in the copper tubing because the noise is faint and water pressure is decent. I can see the rock in the crawl is wet and water is dripping from the joist. This also explains why my electric bill was double last month. Thanks for the advice.

    Btw, I used to live in town houses off Spit Brook Road across from the Tara Hotel. Back in the '80s. Great place to live.
  18. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,052
    Location:
    NW Ontario, Canada
    Slab or crawl space... same difference. Essentially the leak was were it may go unnoticed, which was my point.

    Anyway, glad you got it sorted.
  19. higgledy

    higgledy Member

    Messages:
    45
    Location:
    21701
    Thanks lligetfa.
  20. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
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    Location:
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    quote; Here is a link to a water heater problem nearly exactly like mine. He's final solution was to replace the water heater.

    A plumber bought a new heater to replace for a customer and then brought it back because it was not heating the water. I told him he had a broken pipe, but he refused to believe me. The supply house did NOT refund his money, but told him they would return the heater to the manufacturer and if they said it was defective and gave them an allowance then he would get his refund. HE came back later, after installing the second heater and said it was a leak.

    As soon as you said the upper element was never satisfied, THAT made a leak the only possibility. As far a "high watt density" elements are concerned, they are cheap but almost useless. I have had them fail within weeks of installation. Plus, I never use 3800 watt elements, only 4500 watt ones. And they are either "low watt density" or "lifetime" Ni-Chrome elements. 3800 watt elements are advertised as "energy saving" that only means that they use less power per hour, however, that also means that they have to run longer to heat the water.

    A "good" plumber would have detected that problem in a few minutes, WITHOUT replacing all the heater's components which were probably NOT defective.
    Last edited: Nov 5, 2012
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