On 20 Jan, 14:57, Andy Dingley wrote:
On 20 Jan, 14:46, cynic wrote:

Never come across cast iron firebacks then?

Yes. They're bedded in mortar, which has a similar heatsinking effect.
If they're not, they can crack too.

Quite the opposite to heat sinking, the refractory retains the heat so
the cast iron attains a higher temperature. Solid fuel (coke) boiler
firebars and fireplace grates are also made of cast iron and attain
red heat (1000C) on occasion. When in a hole stop digging!


Besides which, firebacks are cast in thicker sections than back
boilers.

Its probably not cast iron anyway but mild steel.

No, mild steel rusts through too quickly.

I should tell Dunsley and other companies who make wrap round high
output solid fuel back boilers from 4 mm mild steel with long service
life. I am sure they will be fascinated by your information.


There's advice linked from the HSE site on a recommended process for
decomissioning. I think this was linked from here recently too. Mostly
(AFAIR) it involved a drilled hole moderately high up, then slowly
pouring dried sand down a pipe.