On Sun, 14 Sep 2008 23:57:53 +0100, Andy Wade
 wrote:

>Derek Geldard wrote:
>
>> If the  input thermostat sticks closed it would draw current the whole
>> time it was energised that might in some circumstances equate to 3x
>> the energy consumption, but the heater would be getting very hot.
>
>No, for storage heaters the rated input power (3.4 kW in this case) is 
>equal to one seventh of the rated heat charge (24 kWh).  For a full 
>charge from cold the thermostat will remain closed for the whole 7 hr 
>period.  The consumption in 7 hours will not exceed the rated 24 kWh, 
>give or take small tolerances on the element resistance and supply voltage.

That's not it then !!!

Although to be fair by 3x the energy consumption I did mean 3 x the
steady state consumption IE a heater with some residual heat and the
thermostat set low (bit of an unlikely combination).

A shorted input thermostat was the fault condition I thought the
manufacturers helpline guy could have been on about. I can't think
what else, can you ?

Derek

Derek Geldard wrote:

> That's not it then !!!

I don't think so.

> A shorted input thermostat was the fault condition I thought the
> manufacturers helpline guy could have been on about. I can't think
> what else, can you ?

As I said earlier you can imagine a partly shorted element causing an 
increase in input power, but any such fault is likely be quite transient 
for the reasons I gave.  Also all storage heaters I've ever had anything 
to do with have a second overheat protection 'stat (with a 
non-self-resetting cut-out action) in series with the mains input. 
Anything causing a ~3 kW heater to draw 9-10 kW is going to cause that 
to trip if none of the other outcomes I mentioned apply.

-- 
Andy