Never ran into this one before

Discussion in 'Water Heaters and Softeners' started by phishfood, Jul 17, 2013.

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  1. Jul 17, 2013 #1

    phishfood

    phishfood

    phishfood

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    Sold and installed an electric water heater a couple of months ago, the customer did the startup as he didn't have water or electrical turned on yet. Got a call, either VERY hot water, or no hot water and ECO (red reset button) is tripped.

    I checked power, thermostat settings (both were set to 125). No power fed to upper element, the bottom element had power and was heating. I drew some water from the T&P valve, it was only reading 110. I played with the upper thermostat setting. To get it to send power to the element, I had to set it to 140. So I knew it was bad, changed it, and the upper element energized and started heating. But the extremely hot water and the tripped ECO was bugging me, couldn't figure out why those had been occurring.

    After thinking it through, here is what I think was happening. The upper thermostat was obviously reading incorrectly, so it was never sending power to the upper element, so the water toward the top of the heater was not getting hot before the bottom element turned on. The bottom element stayed energized, and was continuously heating water, but the bottom thermostat was never cutting power to it because the hot water was displacing to the top of the tank. The water at the top of the heater was getting very hot, up until the point that it was tripping the ECO.

    Whatchya think of my conclusion?
     
  2. Jul 17, 2013 #2

    IFIXH20

    IFIXH20

    IFIXH20

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    Phish,The problem may have stem from the lower t'stat. Usually what happens is the lower t'stat contacts weld themselves together from arching when closing due to electricity passing through them (it's not a very strong weld) once lower t'stat contacts are stuck/weld closed the lower heating element heat continously to the upper t'stat eco/limit switch trips. The contacts may even open after sticking/welding. I have found this to be more common on the t'stats that have letters(temp setting) on them. This is a common problem I find that lots of tech overlooks. The top t'stat/ heating element is the master and the lower is the slave, if the unit is not heating up top first the lower should not come on.
     
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  3. Jul 17, 2013 #3

    phishfood

    phishfood

    phishfood

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    I did check the operation of both thermostats before deciding to replace the top one. Adjusting the bottom one down to it's lowest setting cut power to the lower element.

    In this situation, the upper thermostat was thinking that the top of the tank was already heated up, due to the faulty reading the thermostat was taking.

    Thanks for bringing that up, though. It could very well save me some hair pulling one day.
     
  4. Oct 6, 2013 #4

    robmcg

    robmcg

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  5. Oct 6, 2013 #5

    phishfood

    phishfood

    phishfood

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    Actually, I have become convinced that is EXACTLY what happened. I ended up getting called back again, because of no hot water. Both elements were fried, which I have only ever seen on a new water heater because of dry firing.

    My bad, I should have never installed the heater without the ability to fill it with water right then and there. Never again.
     
  6. Oct 6, 2013 #6

    robmcg

    robmcg

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