[TheForge] Re: coal forge flues

[Marc Godbout]

I think there's still a problem with a hot flue that isn't related to
creosote and chimney fires. The flue itself will still get hot during
normal operation. A fire inspector would be concerned that the flue
doesn't get hot enough to start combustion in the wall or ceiling/roof
that it's going through.

--Marc

On 1/14/08, Mike Spencer <mspencer at tallships.ca> wrote:
>
> Bruce wrote:
>
> > What you want to do is convince him that the forge
> > flue will never get as hot as a wood stove.
>
> In particular, neither a coal forge nor a propane forge will coat the
> inside of the flue with "creosote" -- highly inflammable wood
> distillates that are volatile at stove-fire temps and solid at lower
> temps.  The really disastrous flue fires arise from running a "normal"
> wood fire and allowing a heavy build-up of creosote to accumulate,
> then running a hotter that usual fire that ignites the accumulation
> near the stove.  Then the flue fire propagates rapidly along the
> creosote in the rest of the flue until the whole thing is a
> self-fueled blowtorch, spewing chunks of flaming, coke-like carbon and
> heating the flue red hot or (depending on the available air inflow)
> hotter.
>
> Doesn't happen with a forge flue.
>
> If you let the flue fill with heavy coal smoke during start-up, you
> can have a short-duration "event" when the smoke ignites and a
> fireball flashes up the flue.  If the joints (or mortar) in the  flue
> aren't tight, the overpressure during this event can blow tiny sparks
> of burning soot out through any gaps.  But no sustained, self-fueled
> blowtorch effect.
>
>
> FWIW,
> - Mike
>
> --
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                            /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
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