Water Heater Pulling 18 Amps Continuously - Not Heating

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Etbrown4

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Been doing plumbing and electrical work for nearly 40 years and here is a new one for me.

50 gal elec water heater, maybe 3 years old. Rated 4500w

It is pulling 18a on both hot wires supplying the heater so that's at 230v, measured by an Amprobe.

There is no leak and the pressure relief is not leaking either.

One wonders how a heater can draw it's rated current and not heat water.

Elements test ok. Resets are not tripped.

I know there can be issues with broken dip tubes and cross connections, but can't really see how either could apply here.

I also know that the situation I describe should be a physical impossibility, as current drawn is current used, and will yield an equivalent amount of heat into that water!

Tips appreciated


Water Heater Pulling 18 Amps Continuously - Not Heating
 
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DonL

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Did you check to ground for a shorted element ?


Good Luck.
 

Etbrown4

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It becomes more complex...

230v measured across top element when powered on. Checked with 2 different meters.

Top element powers on first.

Resistance across both elements is 12.8 ohms.

18 amps still being consumed by top element....checked with 2 Amprobes.

Neither element is grounded to the frame.

The heater displays no sign of heat, top or bottom, and after an hour of consuming 18a, the hot side is cold. and yes, I know that the problem described is in theory, impossible. If it was an easy one, I would not have posted it.

Hum.............. where is that current going? It has to result in heat. ..or a bad reading somewhere.
 

Etbrown4

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using digital meters.

also have 2 side by side water heaters in this installation.

both using the same current.

latest idea....turning off water supply and outlet from problem heater.

thereby isolating water in the tank.

will report what happens next,
 

DonL

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using digital meters.

also have 2 side by side water heaters in this installation.

both using the same current.

latest idea....turning off water supply and outlet from problem heater.

thereby isolating water in the tank.

will report what happens next,


Depending how the two are wired together, You may be reading the current that the working unit is drawing.

You can not measure the current at the T-stat input, you need to measure at the element connection, to tell what that element is drawing.

If you are measuring the current at the correct place and the element is not getting hot, then the wiring must be. And the element is most likely shorted.

Are You measuring at the Element ?

Are these heaters in series or parallel ?


Good Luck.
 
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Etbrown4

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solved!

Old man winter caused this one.

This property has a pool equipment room and outside shower which is remote from the house.

The Pool man came yesterday and turned on water to that equipment room and left.

Our sub zero winter froze a 1/2" cpvc hot water line in that remote location, though the water supply had been off for the winter. Unbeknownst to everyone, the hot water ran all night long, making the water heater seem as if it was not heating...when it was.

Sure enough the 18amp draw was right, watts were consumed! The leak was small enough and the flow moderate enough that at the heater there was no perceptible sound of water flowing. The sound at the heater was just the normal sound of the element being on.

We chased a similar ghost 25 years ago with a sneaky T&P valve leaking. In that case it was a similar slow leak, but still enough to cool the hot water. In that case the outlet for the t&p exited two floors below outside of another condo unit, so similarly we never saw the outflow until many hours later. :cry:

Thanks for all the tips! All contributions appreciated.
 
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