On 19/10/10 20:37, Andy Champ wrote:
On 19/10/2010 17:16, Tabby wrote:

How is a non-flammable metal/sand heating element in an enclosed steel
space going to catch fire?


Presumably the element is at the bottom of the oil container, so the
heat is carried away by rising hot oil.

As the oil level drops it will cease to circulate, the element now being
near the top of the remaining oil.

The oil nearest the element will now receive the entire element output.

Do not leave it unattended!

Andy

None of this would be a problem if regulations required:

a) High temp thermal fuse fixed to the element at the highest point (ie
lack of oil detector)

b) Lower temp (just under the boiling point of the oil) thermal fuse in
the oil close to the element.

That would constitute enough failsafes for me to feel happy. Alas
sometimes you're lucky if you get any thermal fuses - or if you do, that
they've been sensibly placed.