On Aug 20, 9:45*pm, NT wrote:
On Aug 20, 3:16*pm, Stephen wrote:

On Thu, 20 Aug 2009 04:18:22 -0700 (PDT), NT
wrote:

When replacing a heater you should have the tank full initially, once
its loose then turn tap on and water supply of to drain it.

But don't they drain from the top? I thought cold water went in the
bottom and hot water came out the top?

Is there a reason that butyl cables are used with immersion heaters? I
know they have to be heat resistant but why not heat resistant PVC? I

no such thing

There's both hehttp://www.tlc-direct.co.uk/Main_Ind..._Heat_Resistan...

Well... I sense confusion. Yes there's 90C pvc versus 70, the term
'heat resistant' only means its to some degree more heat resistant
than the more common pvc, that doesnt make it comparable to high temp
cables such as butyl rubber.

Then there's also the q of what happens when temp rating is exceeded,
rubber and pvc behave somewhat differently.

NT



There's to some extent differing meanings to 'high temp' in this
situation. PVC flex can be rated to 90C, but running 13A through it
_and_ connecting it to 70C heater connections will likely overheat it.
The butyl rubber leads used on immersions have much thicker conductors
to minimise self heating, and enable them to function ok when
connected to a hot heater.


NT