Posted by nicksanspam on March 1, 2005, 6:41 am
>...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.
Thick works better, IMO, but thin is cheaper.
Ts Tw
| R | 2/3
600 -- --> --*---www-------www--- 70
I |
| 1/3
---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:
Ts Tw
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?
Nick
Posted by nicksanspam on March 2, 2005, 6:39 am
> Ts Tw
> | R | 2/3
>600 -- --> --*---www-------www--- 70
> I |
> | 1/3
> ---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:
> I ------------------------>
> Ts Tw
> 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?
It's just Ohm's law, with different units:
I = (142-70)/(1/3+9.8+2/3) = 6.7 Btu/h, so Tw = 70 + 6.7x2/3 = 74.4 F,
and Ts = 74.4 + 6.7x9.8 = 139.7.
Nick
Posted by John on March 2, 2005, 4:47 pm
If you get a chimney fire the temp is gong to be much higher than 600 F
I have seen stove pipe turn cherry red just from a wood stove's draft
out of control
XML site map
>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.