[TheForge] coal forge exhaust system

[CGRAF]

Squirrel cage of the shop in general is in good portion dilution air and 
is around the temp if the shop ceiling.

I had at one time a conventional draft vent on my forge a  rain cap on 
to about 30ft up had the 50/50 lead solder joint melt out. Luckily it 
was riveted also. (The cap had been mad for another use on a flat roof 
vent and it was re-purposed)

I do not think that there is much cooling going on in the flue itself.