Do-it-yourself installation of a furnace with a remote firebox

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It is not always convenient to load the sauna stove from the steam room. If there is a remote firebox in the main rooms of the bath, there will be no chips and dirt, and when using coal as fuel, an unpleasant smell will disappear. We will show you how to install the external heater correctly and safely..

Do-it-yourself installation of a furnace with a remote firebox

What is specific about a stove with a remote firebox

The choice in favor of a remote firebox can be dictated by a number of reasons: hygiene, aesthetics, lack of free space. And yet, giving preference to such a design, you need to understand that the benefit in the future should compensate for the complexity of installation. And there are much more of them in a stove with a remote firebox than in a conventional stove..

External furnace

First of all, fire safety requirements apply. If the traditional design of the furnace requires either maintaining a distance from the combustible coatings, or lining them with a non-combustible screen, then the presence of a combustion tunnel implies a tight adjoining of highly heated parts to a wall or partition. In this regard, it is required:

  1. Replacing a section of a wall or partition with a non-combustible and heat-resistant material.
  2. Covering the tunnel in thermal insulation material, preventing overheating and damage to the finishing layer.

Sauna stove with external firebox

The situation is complicated by the fact that the whole action takes place in a bathhouse, which is traditionally built of wood and trimmed with wood. In connection with this feature, the decision to install a furnace from a remote firebox should be made in advance with the appropriate additions to the construction project. In particular, it is possible to recommend replacing the entire partition through which the channel will pass with a lightweight non-combustible material with a minimum value of thermal shrinkage. An example of this is tongue-and-groove gypsum boards, warm ceramics or hollow bricks..

Installation sequence

The main specifics of installing a stove with a pass-through firebox is limited by the very place of the passage, otherwise the same requirements apply as for a conventional stove. Despite this, you should plan your actions correctly so that, in the end, the correct relationship of technical and decorative elements is ensured..

As many people know, the weight of a stove with a full load and brick lining can reach one ton, and therefore installation directly on the floor would be a deliberately wrong decision. This can be done only if we are talking about a relatively small stove (8-10 kW) and only with the correct organization of the floor supporting system. In other cases, it is required to cast a pedestal from reinforced concrete, which will rise 50–70 mm above the plane of the floor covering. Do not use flammable materials for finishing the stove base.

Sauna stove foundation

Now we will consider two special cases – the passage of the firebox through the non-capital partition and the passage through the load-bearing or external wall. In the first version, the partition does not have its own foundation; it is attached to the subfloor, which is possible due to the relatively low weight of the structure. However, if part of the partition is replaced by a heavier material (brick), it is quite advisable to continue the pedestal deep into the section of the wall for its entire thickness.

Sauna stove foundation

In the case of a passage through the main wall, additional difficulties arise. On the one hand, it is possible to tie the pedestal to the foundation, on the other hand, this increases the risk of the monolithic structure breaking due to uneven settlement of the building. Such a bundle can be performed only if the pedestal is poured simultaneously with the foundation, the reinforcement is connected with anchors, and there is a common cushion of sand and gravel under the pedestal and foundation. It seems unlikely to arrange such a bundle of a pedestal with a foundation upon completion of construction, in such cases, the passage and protective screen should be laid out separately with a gap of about 5-10 mm.

Sauna stove foundation

Preparing the right plinth is only the first part of the task. The sequence of further actions is as follows:

  1. Installing the furnace body.
  2. Installation of a furnace tunnel.
  3. Alignment of the entire structure as an assembly along the plane of abutment of the fire door to the finish.
  4. Installation of a chimney and, if available, a hydro-connection of the furnace.
  5. Passage laying and decorative finishing.

Opening preparation

Agree that not every builder can boast of the ability to carefully plan and absolute foresight. Therefore, it makes sense to give some practical advice on preparing an opening in an already built partition.

The most problematic case can be called the passage of the firebox through a wooden frame wall. With a standard column pitch of 40-60 cm, at least three of them will have to be cut, while maintaining the structural strength of the upper section of the wall. This can be achieved by installing a more massive beam as the upper guardrail of the passageway, supporting it along the edges with additional posts. The technique is similar to the preparation of wide window openings during the construction of a frame house.

Firebox passage through the frame wall

If the partition is folded from a bar, the opening in it is simply cut out with a chain saw, and then a lining from a board is mounted from the inside with a width of the entire thickness of the wall and a thickness of about 50-60 mm. The only pitfall here is that the length of the timber fragments remaining at the edge of the opening should not be less than 30 cm, respectively, you will have to play a little with the stove shifting to one side or the other.

Opening for the oven in the bath

To make an opening in a stone wall, slotting work cannot be avoided. The good news is that it is enough to simply tear off the combustible finish from the stone wall, but it makes no sense to carry out a complete replacement of the material at a specified distance from the tunnel. In this case, after installing the furnace body, the outline of the tunnel is drawn on the wall, the opening is cut out without additional reinforcement with a tolerance of 20-30 mm in each direction.

Fire safety requirements

So far, we have not deliberately touched on the question of how far from the furnace tunnel should be replaced with a non-combustible material and how to arrange a fire-safe, heat-resistant salary. The generally accepted norm is the replacement of a section of a wall with a width of 150 cm and the same height with a non-combustible material. It is characteristic that this does not take into account the section of the furnace tunnel and its design features. So, if the tunnel has a telescopic device, it will have double walls in the passage area, and therefore the heat transfer will be significantly reduced. The best guideline in determining the dimensions of the preparatory opening will be the recommendation of the manufacturer of a specific furnace model.

The size of the portal for the sauna stove

Iron sheet size in front of the furnace

One of the mandatory requirements when installing the stove is the installation of a fireproof covering on the floor in an area of ​​0.5 m from the fire door. Such a coating can be a tile or galvanized steel sheet. It also makes sense not to arrange masonry close to the furnace tunnel. It is much more correct to provide a gap of about 20–30 mm on the top and sides, which is subsequently sealed with mineral wool. Such a damper will allow leveling the thermal expansion of the metal and maintaining the integrity of the finished masonry..

Steel sheet in front of the firebox door

Aisle finish and installation site

The time has come to move from general concepts to practice. When the opening is prepared, the stove is installed and the chimney is mounted, the passage zone is closed. First, a lining is assembled from a brick under the furnace tunnel: by orienting the stones in different positions and adjusting the thickness of the seam, you need to achieve a tight backfill.

Masonry brick portal for a sauna stove

Next, lay out the side sections. Usually, at the edge of the opening, bricks are pushed together, forming a small protrusion, which provides additional protection for the finish and gives the masonry a more complete look. The sections between the ledge and the furnace door are laid with bricks in “spoons”. In this case, the laying can be performed in two layers. Alignment of the masonry plane is carried out along the frame of the fire door.

Brick portal for a sauna stove

The top row is laid out by analogy with the extreme bricks, thus forming the frame of the firebox. If, after laying the final butt row, a gap of more than 20 mm remains in the opening, this is a good opportunity to install a narrow shelf above the firebox – just insert a board of suitable thickness into the gap. After the mortar has set, the brickwork is lightly sprinkled with water and embroidered with a semicircular knife.

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