Hot Water runs out quickly...what's gone bad?


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Old 12-22-16, 05:33 PM
J
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Hot Water runs out quickly...what's gone bad?

Before my 2 hour researching today I knew nothing about hot water heaters except that they had elements that go bad. That being said, I am now familiar with the majority of the main parts. I just bought a new (to me) house, and it has what I expect is an older heater, though I cannot for the life of me find a year on it. It has very nice hot water, but for barely long enough to take a shower.

Here's what I have done:

Checked breaker.
Reset hot temp button.
Used multi-meter to check continuity on both elements.
I went to check the thermostats as follows:
1) Turn lower stat to lowest setting, and upper stat was already as high as it could go.
Checked 240 volts to heater, and also still 240 to stat. No voltage to upper element. So I THOUGHT I had it figured out the upper stat was bad.
Though when I went to turn the bottom thermostat back up, I heard it kick on. I may be wrong, but from reading I gathered that the upper stat controls lower stat, so it should be working if the bottom kicked on?

I'm wondering if since the heater was already set so high, maybe the upper thermostat didn't have to turn on when I checked it. And if so...Then everything seems to check out and I have no idea where to go from here.

Help a newbie out! Thanks guys.
 
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Old 12-23-16, 06:31 AM
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Lower element bad will give you the symptoms you described.

When some of the hot water is used the lower element will come on. When most of the hot water is used the upper element will come on and the lower element will go off. Only one element operates at a time. When the upper part of the tankful is heated the upper element goes off and the lower element comes back on.

If the lower element is burned out then after the upper element goes off nothing more happens until the smaller amount of hot water at the top is used and the upper element comes back on.

The upper thermostat switches between upper element and lower element. The lower thermostat switches between "any element" and "all off".

Don't forget, you need to unhook everything from one of the two places where you touch the multimeter probes just before doing a continuity measurement.

Here you would unhook all of the wires (label them first) from one of the two terminals of the lower element in order to show that it had continuity (was not burned out). Also measure continuity between each element terminal and the body of the heater, should not be any continuity here.

Another possibility for quick running out of hot water, the dip tube in the cold water inlet is broken.
 
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Old 12-23-16, 03:17 PM
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Yes I did disconnect everything. I can believe that the bottom element is bad, and am about to take it out and see what it looks like. Though it did pass continuity, there appears to be some mineral buildup on it possibly. Is the dip tube something you can replace? Haven't come across that suggestion. Thanks!


/e The tank is draining incredibly slow, so I am assuming mineral deposits are a big factor around here.
 

Last edited by Joshua Christie; 12-23-16 at 03:46 PM.
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Old 12-24-16, 07:35 AM
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I can believe that the bottom element is bad, and am about to take it out and see what it looks like.
It's not necessary to take it out. Unless it would be burned through you can't tell anything by looking at it anyway. When you have 240 volts across the element terminals it should be drawing 18 to 19 amps. If it has no current draw it is bad.

From a cold start the top element heats the water at the top of the tank first and then the lower element takes over to heat the bulk of the water in the tank. Good hot water for very a short period is a classic example of what happens when the lower element is bad.
 
 

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