- Nov 27, 2012
- 0
Question:
We recently put a Jotul woodstove (#3) in an existing fireplace hearth, venting thru the existing chimney. The nearest wall is 20" away (only on the left side) and I have installed a heat shield against that wall. However, going up either side of the fireplace are two 2x4 studs covered in wallboard that have always been there (the 2" is what "sticks out", the 4" is flat against the same wall as the f-place). These are only 16" away from the stove. We have not been able to find a protective shield that will cover such a dimension, so they are "open". I guess my question is how much heat will these 2x4's receive at 16", and, would it ever be enough to cause a fire hazard. What is the ignition point of wood? The stove surface temp usually runs around 500F, and if I touch the boards, they do not feel that hot.
Answer:
Heat radiation from a stove is greatest from one flat surface (top, back, front, etc) toward another flat surface. Radiation at angles is greatly diminished.
I cannot tell you to place a stove any closer to combustibles than the manual states, however we can discuss rules of thumb and the temperatures are which wood might ignite.
If wood can be touched, it is probably below 130 degrees F, since water of that temperature would burn you. Wood can easily take temperatures up to 200 degrees F and more, as is evidenced by the fact that Steam and Hot Water radiators in homes have pipes which often have contact with wood. These pipes can be 180-200 degrees.
It is thought that prolonged heating of wood at temperatures over 250 degrees can eventually turn the wood to charcoal, which may have a much lower combustion temperature. Never the less, there is no proof that I know of that combustion of wood is supported at temperatures below 250 degrees..and even then it might require long term (months) of heating at that temperature.
Our store often made custom heat shields for certain installations using a sheet metal brake (a device that bends metal). We'd paint them to match the stove and mount on 1" spacer from the combustible material.
We recently put a Jotul woodstove (#3) in an existing fireplace hearth, venting thru the existing chimney. The nearest wall is 20" away (only on the left side) and I have installed a heat shield against that wall. However, going up either side of the fireplace are two 2x4 studs covered in wallboard that have always been there (the 2" is what "sticks out", the 4" is flat against the same wall as the f-place). These are only 16" away from the stove. We have not been able to find a protective shield that will cover such a dimension, so they are "open". I guess my question is how much heat will these 2x4's receive at 16", and, would it ever be enough to cause a fire hazard. What is the ignition point of wood? The stove surface temp usually runs around 500F, and if I touch the boards, they do not feel that hot.
Answer:
Heat radiation from a stove is greatest from one flat surface (top, back, front, etc) toward another flat surface. Radiation at angles is greatly diminished.
I cannot tell you to place a stove any closer to combustibles than the manual states, however we can discuss rules of thumb and the temperatures are which wood might ignite.
If wood can be touched, it is probably below 130 degrees F, since water of that temperature would burn you. Wood can easily take temperatures up to 200 degrees F and more, as is evidenced by the fact that Steam and Hot Water radiators in homes have pipes which often have contact with wood. These pipes can be 180-200 degrees.
It is thought that prolonged heating of wood at temperatures over 250 degrees can eventually turn the wood to charcoal, which may have a much lower combustion temperature. Never the less, there is no proof that I know of that combustion of wood is supported at temperatures below 250 degrees..and even then it might require long term (months) of heating at that temperature.
Our store often made custom heat shields for certain installations using a sheet metal brake (a device that bends metal). We'd paint them to match the stove and mount on 1" spacer from the combustible material.
