9 Oct
2012
9 Oct
'12
11:09 a.m.
On Oct 8, 2012, at 6:17 PM, jim s wrote:
On 10/8/2012 10:59 AM, [David Riley] wrote:
Indeed! The folks who rehabbed it did it the right way; they
ran the exhaust chimneys for the furnace and the water heater
(which do get quite hot, along with ferrying and potentially
depositing partial combustion byproducts) up through the
chimney and ran the actual ventilation ductwork outside the
masonry. They built extra space into the drywall, which is
what I ran my conduit through (there was enough left-over
space for a 2" pipe).
There are some sort-of firebreaks going on between floors
which the vent ducts go through, but they're not completely
covering the aperture. I'm not 100% confident it would pass
code, but it's what I've got for now. I'll have to ask a
code inspector about it someday.
> >I was just lucky enough that the folks
who had rehabbed the house
> >back in the '80s and added an HVAC system had left extra space
> >around the old chimney when they put in the duct work (and also
> >lucky that said space intersected my office).
Off the computer topic here,
but on topic of not burning your house down, there is a code required keepout between
chimneys and hot exhausts that must not have combustibles there. If you are in a
situation where they took an old brick chimney and lined it with a stainless insert it
probably isn't the problem you would have if it were not. Usually they don't trust
masonry w/o lining it after it gets old for gas and heat leaks anyway. But if you are running something the creates creosote
inside the system, you might have a fire which could set off your conduit if it isn't
fireproof. Creosote fires for wood are common if you have the right conditions.
We have all natural gas (from free range burritos!), so
creosote isn't really a problem. Not that there aren't
potential problems with partial combustion products of
natural gas, but they're much less common, especially with
a well-maintained furnace.
- Dave