"Tim Watts" wrote in message
...

On 24/02/17 12:38, Chris Hogg wrote:
You're suggesting the flame would strike back through the bleed valve
into the radiator? Very unlikely I would think. The mass of cold metal
would quench the flame to below its ignition point, in much the same
way as the gauze in a Davy lamp used by coal miners does.


It won't - there's no O2 in the radiator to sustain combustion.


Well there may be if there is air in there !

It IS possible for air to be drawn into a sealed system at loose compression
fittings on the suck side of the circulating pump, and those fittings not
leak out water in normal use - I've seen it, but it struck me as very odd at
the time.

Andrew