Setting temps on electric water heater


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Old 04-28-13, 04:33 PM
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Setting temps on electric water heater

We have a Powermiser 12 from Sears and I want to say the lower element may be taking a dive. We are on well water and use a softener, lower element is original and is about 5 years old.

I tried to get the lower stat the same temp as the upper, not sure if this is the correct procedure. What is the ideal temp split for the heater or should it be the same? Seems we get a good rush of hot water for about 10 min then the max temp drops about 10-15 deg for the remainder of the tank.
 
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Old 04-28-13, 06:00 PM
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The same setting or the lower slightly higher is fine as both upper and lower are never on at the same time. Some may vary, but your upper stat is the primary control. It turns on the upper element until the upper stat reaches the set temp and then transfers power to the lower stat. It powers the lower element until the lower portion of the tank also reaches the set point and turns off. The lower then cycles as needed to maintain the whole tank in stand-by.

When you use some water the cold water is delivered to the bottom of the tank, assuming the dip tube is intact. The lower stat will activate the lower element and try to keep the whole tank up to temperature. If it falls behind, the upper stat will take control and activate the upper element in an attempt to heat the water closest to the exit point.

In your case, the upper half of the tank is hot, but quickly falls short as the lower half is probably not. IMO, this would point to a lower stat or a lower element, both of which can be tested.

Other possibilities would be a broken dip tube or sediment in the bottom (which would usually take out the lower element).

I hope I got it right, others will correct me if I missed.

Bud
 
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Old 04-28-13, 07:22 PM
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I'm moving your post from the home heating (boilers) forum to the water heater forum.

Bud's pretty much said it all...

I might add that well water is often quite a bit colder than city water. Mine comes up at 57 pretty much year round. City water is most likely at least 10 warmer than that. So the temperature rise that the heater has to deal with is that much greater.

Based on what you've described though, I believe I would investigate the 'dip tube'.

What temp are you setting the thermostats to?

Is there a 'tempering valve' on the hot outlet?
 
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Old 04-28-13, 07:25 PM
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Makes sense, and I was curious if I could alter the lower stat, which way could I go and what you stated clears things up.

I can use an ohm meter to test the element but how would I check the stat? Is there a way to sync both stats by using an ohm meter?

From what I gather, if the lower is set to a lower temp then the upper tends to heat the entire tank, which is not ideal.
 
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Old 04-28-13, 07:31 PM
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Sorry, we must have posted at near the same time, I looked up and down twice and totally missed the "Water Heater" forum....my bad.

Temp is at the "B" position, roughly 125-130 deg, have 2 kids so I don't want to crank it up too high.
 
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Old 04-28-13, 07:31 PM
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The upper thermostat and element will never heat the entire tank, or at least not in any kind of useful time frame.

The lower thermostat and element is only powered when the upper thermostat is satisfied, the upper element is off.

With the power off and the leads to the elements disconnected, use your ohmmeter to check for a grounded element bu placing one probe against the metal tank and the other probe to each of the two element terminals. There should be infinite resistance.
 
 

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