Hmm.
I've been getting high power bills over the last 2 months. I wonder if
I'm getting a similar problem (cylinder is ~20years old). Could just
be the cold weather.

I'm guessing the "airblocks" were a mixture of hydrogen & oxygen from
the water breakdown. If I get the same, maybe I'll try applying a
match! Or maybe not - might blow my taps off.

RP

2009/8/7 Jinx <joecolquitt@clear.net.nz>:
>> Can I presume that a GF(C)I (or whatever you call them there--
>> Residual Current Device?) is not fitted to the water heater?
>
> Only a resettable 16A circuit breaker in the fuse box
>
>> If the insulation is damaged, the 'hot' wire will conduct electricity
>> to the ground on your hot water heater. It will bubble like crazy
>
> The electrician did ask if power bills had been unusually high lately
>
> So any defect in the insulation will make a hot spot that spreads
> as metal is eaten
>
> Eventually, I suppose then, enough of the wire conducts to trip the
> circuit breaker. AIUI water is a poor conductor compared with
> wire. So if the portion of the element closest to the active terminal
> (where the potential difference is greatest and where the corrosion
> starts) was more electrically insulated from the water this might delay
> corrosion
>
> Also, for a few days before the element finally opened, I'd noticed
> what I thought were air locks in the hot water pipe. The HW taps
> sputtered before good flow. I presume that this was due to the
> bubbling you mention. If this is gaseous steam inside the tank it
> might be a pressure or condensation effect at the taps
>
>
> Thanks for all comments/explanations
>
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