Go to NFPA site; lots of info t here. Can't find my link to it;
Google for it. Also try "wood stove"+clear while you're there
for other good info.
| My new wood stove lists 15" to combustible surfaces at the
| Anyone know how far I can cut that back to a stud wall faced
| cement board and ceramic tiles?
If the cement board and ceramic tile are attached directly to the stud
walls, I don't believe there is ANY reduction in the clearances. The heat
can transfer directly through the tile/backer to the studs.
On the other hand, if the backer/tile is spaced away from the wall about an
inch (with non-combustable spacers), the clearances CAN be reduced. I don't
recall how much right now, you would need to check with the wood stove
manufacturer and/or your county officials about that.
Depends on how quickly you want to burn the house down! I would NOT reduce
the distance and I would put 1" noncombustible spacers in the back board.
Remember, when you are sleeping or away from home - the fire has it's own
I've use wood stoves all my life and always have a healthy respect for
There are approved methods of doing it. Check your local codes, check with
experienced people at a stove shop as they should have the right materials.
Doing it the wrong way can be a very expensive lesson. In most cases, there
must be an air gap between the board and the wall but it has been a few
years since I've kept up with that sort of thing. This is something you
don't want to cheat on. That stove can easily be cranking along at 600+
I run my stove at 400 on a regular basis. At least once a day, I crank it
up to 600+ for about 15 minutes to clear out the creosote. Been doing that
for 24 years now on a cast iron Vermont Castings. While I don't run it
there for long, it can easily reach those temperatures and you have to allow
it here. The installation instructions for a new
stove should state that. In addition the
county/city building codes will state it. A 1"
space with some airflow should about cut the
required distance in half. The surface temp of my
ceramic shield (actually light weight cement with
ceramic tiles (also a 1" space to the drywall)
would get high enough one couldn't hold a hand on
it, but probably never exceeded 160 degrees.
Removal of that back after 20 years of use showed
no heat damage to the drywall.
If one doesn't give a hoot about the code
requirement but is just interested in safety,
installation of a thin metal shield (or you can
even try it with aluminum foil) 2-3 inches from
the stove back will provide the greatest safety.
Think stove -- metal shield-- wall. 3" between
the stove and the shield and 2-3" between the
shield and the wall will result in an wall temp of
less than 110 degrees at any normal stove
operating temperature. Thin shiny metal is the best.
I'm not necessarily recommending this, but it
proves that the safety recommendations are not
realistic. A metal shield (and some stove makers
sell them as accessories) with an air spacing is
far superior safety wise than any ceramic against
Thick works better, IMO, but thin is cheaper.
| R | 2/3
600 -- --> --*---www-------www--- 70
If the stove temp is 600 F, I = 0.1714x10^-8(600+460)^4 = 2164 Btu/h-ft^2.
A 90% reflective shield would absorb about 10% of this, ie 216 Btu/h-ft^2.
The linearized radiation conductance R = 1/(4x0.1714x10^-8(70+460)^3x0.1)
= R9.8, with 2/3 airfilm conductances. Here's one equivalent circuit:
1/3 | 9.8 | 2/3
---www---*---www-------www--- 70 F
| 142 F = 70+216x1/3
What are the shield and wall temps Ts and Tw?
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