Concept of distance from furnace wall, stove and chimney

Concept of the air layer on the furnace wall and the distance from the stove

How safe is the distance from the wood stove to the furnace wall?

How to make a furnace wall

What should I use for the material?

Isn't there a lot of people who are worried about it?

Today, I would like to write about the idea of ​​the position of the furnace wall and the wood stove, and the material.

This is the standard of the American National Fire Protection Association .

When installing chimneys, heaters, and boilers at the Fire Safety Association???

If you are interested, the original text is in English, but if you translate it from a site such as Google Translate, you may be able to read it.

To the last, this is a chart based on my interpretation and interpretation of American standards.

For that reason, I think it would be better to use it as a reference for construction and think about safety in your own way.

The installation of wood stoves is more common than in Japan, so I think it would be good to refer to countries like Japan where wood stoves are underdeveloped.

In Japan, the standards for installing chimneys are stipulated in the Building Standards Law.

However, since it is written based on a single chimney, it does not meet the criteria for using an insulated double chimney.

Still, in the case of a new building, it is necessary to apply for a building certification, and at that time, there is guidance from the local fire department, and they are told to follow it.

So be careful with new construction.

From here on, I will refer to articles on other English sites, and what I understand here, so please let me know if there are any misunderstandings.

First of all, the furnace wall that is generally easy to construct in DIY is a furnace wall made of calcine plate or iron plate with an air layer of 25 mm or more.

In addition to having an air layer of 25 mm or more, it is possible to reduce the safe distance from combustible materials to 1/3 for walls and 1/2 for ceilings by using appropriate materials and construction methods. It is

First of all, regarding the air layer, it is an absolute requirement to create an air flow inside the wall by opening the lower and upper parts of the furnace wall .

Heated air comes out from the top, so open the bottom to secure the air flow path.

And it must be a structure that cools the furnace wall with air.

In addition, if you open the top and both sides and create a structure that allows air to flow from the side to the whole, there is no problem even if the bottom is left open.

However, it may be necessary to devise a way to install the spacers so that the air can evenly circulate inside the wall and cool the wall.

The wall furnace is made of steel with a thickness of 0.6 mm or more, or cement-based noncombustible material with a thickness of 12.5 mm or more.

As incombustible materials that meet this American standard, it seems that 12mm silica gel board, 12mm gypsum board, etc. are easy to obtain.

In addition, even with silica slabs and plasterboards of 12 mm or less, it is considered that the conditions will be satisfied if the thickness is 12.5 mm or more after finishing with noncombustible bricks and tiles.

In other words, if you create the furnace wall with the above method, it is possible to shorten the distance from the wood stove to the wall and from the wood stove to the ceiling as follows.

A wood stove with a distance to the combustibles on the wall of, for example, 45 cm is as follows.

From 15 cm, which is 1/3 of 45 cm, the wood stove can be installed closer to the wall.

For wood stoves with a 90 cm distance to combustibles on the ceiling:

It is possible to install the wood stove and the ceiling closer to 45 cm, which is 1/2 of 90 cm.

In the case of the ceiling, the heat rises and the air is trapped, so the standards are generally stricter than the walls.

Now consider the same furnace wall with 25mm rockwool or ceramic fiber insulation, or 9cm thick brickwork with no air layer or insulation.

This condition is worse than the air layer, and it is possible to shrink it to 1/2 for walls and 2/3 for ceilings.

Insulating materials and 90 mm thick bricks have no air convection, and even if noncombustible materials are present, heat is trapped in the furnace wall itself and the insulating material, making the conditions a little worse.

If the distance to the combustible material on the wall is 45 cm, it will be possible to install the wood stove and the wall closer to 22.5 cm, which is 1/2 of 45 cm.

If the distance to the combustible material on the ceiling is 90 cm, it is possible to install the wood stove and the ceiling closer to 60 cm, which is 2/3 of 90 cm.

We will also tell you how to think about the distance when installing a heat shield on a stove or a single chimney.

This is the idea of ​​the distance when a semicircular heat shield is installed on the back and side of the wood stove body and on the chimney with a distance of 25 mm.

In this case, the distance to the wall can be halved, so if the distance is 45 cm, it will be 22.5 cm.

Also, if the ceiling is 90 cm, it will be 60 cm because it can be shortened by 1/3.

As for the distance from the stove body to the furnace wall when combining the furnace wall with this air layer and the heat shield of the stove body, it is not written, so I do not know.

It is possible to reduce the distance from the wood stove to the furnace wall when both are combined, but it is not possible to say clearly as a numerical value.

If you have any questions, please feel free to contact us from the inquiry column .