testing water heater
Jules wrote:
Hmm, our water heater seems to have become unwell in the last couple of
days - taking a long time to reheat, and whilst the hot water it
eventually produces is still hot (not just warm) it runs out very quickly.
It's a dual-element design, and having just run the tank cold, with a
meter I'm getting 240V at the lower element terminals but nothing at the
top one, suggesting the upper thermostat's at fault (I'll rule out wiring
too in a few minutes, just to make sure it's not a loose terminal or
something silly).
Questions:
1) Just to clarify, should the upper 'stat / element be operating with a
fully-cold tank? I assume both elements should be running in that
situation, but figured I'd check.
2) Do these thermostats change resistance according to temp, or are they
either off or on depending on setting? (I'm just wondering if I can
somehow test it in isolation by blasting it with a hairdrier, or
something, and measuring resistance across the terminals, but maybe that
won't get it hot enough to prove anything)
3) The upper 'stat is a WH-10 7-terminal, but it's a non-adjustable one
(says as much on it, along with something like "factory pre-set to hot
setting"). I can get a replacement WH-10 easily enough, but I've only seen
adjustable ones for sale - presumably I can just drop one of those in,
except that I've no idea what the manufacturer's idea of "hot setting" is :-)
cheers
Jules
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