Fireplace fireboxes: what they are and how to choose them

Today, making a fireplace is not as difficult as it was a couple decades ago. It is not necessary to lay it out of brick, there are metal inserts that need to be designed accordingly. Called this insert – fireplace firebox or fireplace insert. It is made of heat-resistant steel and cast iron. What they are and how to choose, we look further.

Which fireplace firebox is better open or closed

In general, the fireplace as a heating element is effective in a well-insulated house. Then it can be the main and even the only source of heat. But it is not easy to make a full-fledged heating on the basis of a fireplace. In any case, to begin with you will have to decide – open or closed fireplace firebox you need. Open – very similar to the traditional hearth, but modern versions are made of cast iron or heat-resistant steel. And there’s no need to lay it out of brick.

Closed fireplace firebox is made of metal, but differs in that it is hermetic – has a tightly fitted door that separates the fireplace from the room. In addition to appearance, there are many other features. These are the ones that will help you make a choice.

Open fireplace fireboxes

When we think of a fireplace, there is a picture: hearth, crackling wood, dancing flames. Everything is so, but let’s appreciate all the charms of such a heating device:

So, if you need a fireplace only for aesthetics, then an open fireplace firebox is fine. But only you should be aware of all the associated phenomena that you will have to face.

Closed fireboxes

Closed fireboxes have been around for a while now. They are more convenient, economical and safe. Some models have such a large glazing that allows you to admire the fire from almost anywhere. If you also want to listen to the crackling of wood, you can open the door. Here are more advantages:

In fact, the fireplace firebox, this is one of the subspecies of a heating stove. It differs in the wide door, the format of the firebox, and the shape of the vault. But aesthetically, they are much more attractive than standard stoves.

It is worth saying that the fireplace firebox of the closed type, is good as a decorative element. But it can be used as part of the heating system. There are fireplace fireboxes with a water register for connecting heating radiators. This is, of course, an option for the amateur, but also viable. Just when choosing “for beauty”, more rely on safety and appearance. When choosing “for heating”, albeit additional, more look at the performance characteristics, pushing beauty to the background.

Cast iron or steel

Fireplace firebox can be steel or cast iron. In general, disputes about what is better – cast iron or steel for fireplaces and stoves have been going on for a long time. And there is no unambiguous answer. Each option is ambiguous, each has pros and cons. Let’s list them: kaminnie-topki-14 kaminnie-topki-16

• Cast-iron fireboxes weigh more, have a greater thermal inertia. On the one hand, this is bad. Until the firebox warms up, there will be no heat. On the other hand, cast iron takes longer to cool down and it will be warmer after the wood burns through.
• The low weight of steel variants has its advantages – they can easily be put on any slab, without recalculating the load. If the combined weight of the construction of the firebox+portal above 200 kg, it is necessary to reinforce the floor. If the ceiling is concrete, everything is fine, but under the lags, an additional support is needed.

  

• Steel can be welded. This gives a huge scope for different design. Cast iron is only cast, and the creation of new models, a long and complex process. Therefore, cast iron models are more conservative. But the fireplace firebox, most often, is hidden in the portal.
• Steel, even thick and high-quality, burns through. To protect the walls from direct heat, they cover them with heat-resistant materials – make lining. This extends their service life, but depends on the quality of the material and the execution of work. Cast iron walls can withstand fire for decades. No steel, even with a liner, will last thirty to forty years.
• A cast iron fireplace firebox usually consists of several parts. They are joined together in an airtight manner. Steel fireboxes are welded together. The seam is a weak point, but properly executed, it is quite reliable. However, it is often the seams that start the destruction of metals.

  

• If water gets on the hot cast iron, it will burst.
• Cracked cast iron cannot be repaired. It is only necessary to completely replace the damaged fragment. If such models are still produced by the factory, you can order the necessary part. Steel can be welded, put a patch, etc.

Hopefully, you were able to draw a conclusion for yourself, which fireplace firebox is better from steel or cast iron. Both options are not ideal, but preference is usually given to cast iron. It is more durable, which is usually the decisive argument.

Types of fireplace fireboxes

Most of the models are attached to the wall. This method of installation can be considered traditional, so did our ancestors. There is another technology – built-in fireplaces. In this case, the wall or partition is specially modified or built, a chimney and all other elements of the system are laid in them. Such fireboxes are available for installation in the corner (as in the photo below on the left). They have a trapezoidal shape, tapering away from the door. When installed directly against the wall, the body is rectangular.

Corner fireboxes are good because they take up the space that is hardest to use. But the tapered shape of the firebox requires smaller sized firewood. Second point. With the same door width, corner ones have slightly less heat output because the volume of the combustion chamber is smaller. But the fireplace in the corner allows you to save on materials for the portal, because there are already two walls.

By type of glazing

First appeared fireplace fireboxes with straight, rounded or trapezoidal glass. The glass was necessarily enclosed in a metal frame, hinges on the right or left. Accordingly, if the door opens to the right, they are called right-sided, if left, then left-sided. If the glass is symmetrical, it is possible to choose which way the door will open.

Such models are attractive, but the view is still limited. Modern interiors dictate their own rules, and the availability of fire-resistant glass bent shape and transparent fire-resistant sealants, allowed to create more interesting models. In addition to the usual flat door fireplaces, there are more interesting (and expensive) varieties:

• Tunnel (see-through). One fireplace for two rooms, it is built into the wall and heats adjacent rooms.
• Double-sided with L-shaped glazing. The flames can be admired from both sides. They can be right-sided and left-sided.
• Three-sided with U-shaped glass. Only the rear wall is closed.

There are different ways of opening the door: to the side on hinges or lifting up. A firebox with a rising glass is called a guillotine. These options are more expensive, but the fireplace can look like an open fireplace, with the door retracting upward into a slot that is arranged on top. They can work with either a closed or open door. Hinged door options are more designed for closed door mode.

What to pay attention to when choosing inexpensive fireplaces

Conditionally divide all fireplace fireboxes can be divided into three categories: cheap, medium price range and expensive. It’s mainly not about the manufacturer and its name, but about the quality and technology that is used. There are no miracles. It is impossible to buy a cheap fireplace top with the same indicators as the expensive one. But in every price range there are better and worse models. At the same price, the quality can differ significantly. What is typical is that the higher the price range, the less differences between products from different manufacturers. So if you want to choose from the cheap ones, carefully inspect the models you choose.

The first and most important thing is the quality of the metal. If it is steel, make sure it is heat-resistant, check the quality of the seams. They should be even, without swells, caverns, etc. The quality of cast iron is checked by external inspection. The smoother the casting, the higher the quality. The wall thickness of steel and cast iron fireboxes is also important. Especially at the vault, where the heat load is the highest. There the thickness should be maximized.

Tightness of the firebox

The first and most important thing is that the fireplace firebox for effective operation must be airtight. Then it can work in any mode – active combustion, smoldering, etc. This is what distinguishes expensive models from cheap ones: the degree of sealing. Therefore, choosing a budget model, pay attention to the ability to regulate the air supply.

• Air supply system. Usually the air is supplied through the ash pan. Under the door, grooves are made, which are overlapped by movable flaps. A lever at the bottom or on the side. By opening and closing the air supply, we regulate the intensity of combustion. There can be several adjustments, but they all make sense if they allow you to completely shut off the supply. Check how well they fit, how securely they close off the air supply.

  

• The seal on the door. It is made of ceramic cord and goes around the perimeter without skipping. Not at the bottom or on two or three sides. The cord should be wide (extending farther outside the frame) and soft. If it has lost elasticity or is made flush with the slot in a new firebox, there will be no airtightness.
• How the glass is pressed against the door frame. Ideally – a metal corner, which is pressed by holders. And one more thing: the holders should be reliable and made of good metal (you can’t bend them with your fingers).
• Glass sealing all around the perimeter between the glass and the frame of the door. Better the same ceramic cord, but flatter. Sealant is not bad, but cord is better.

  

• Glass cleaning system. These are the holes in the top of the door frame above the glass. Air enters through them and it descends, carrying away soot and cinders. This way the glass stays cleaner longer. Please note: the glass will still need to be cleaned occasionally.
• Method of opening the chimney screen. The cheapest on bolts, but also the most unreliable. If you choose a bolted connection, when installing, provide for the possibility of access, for repair and replacement of bolts or nuts.

As you can see, there are enough parameters and these are only the main ones. There is also the beauty. If the budget allows, choose a frameless door. They look much more solid, although they cost more.

Fuel efficiency

If the fireplace will work for heating, and not just for beauty, its economy is important. Economical it will be when the heat will be extracted to the maximum. Therefore, pay attention to the availability of a secondary air supply.

Usually air is supplied through the grate. It enters the wood, those burn. In the process, more gases are formed. Most of them are flammable and the heat of their combustion is greater than the heat we get when burning firewood. If you ignite these gases, the heat will be much greater. To set them on fire, all you have to do is add oxygen.

For this purpose, holes are made in the rear wall and in the upper part of the firebox. This is the secondary air supply for afterburning of gases. Air is fed into the upper part of the firebox and it mixes with the glowing gases. This mixture flares up, which gives additional heat. This process can be observed. When burning, a fire cap is formed at the top of the firebox. But again we pay attention, this makes sense in a sealed firebox, where the air supply is normalized.

Features of guillotine fireplaces

If you are interested in a fireplace firebox with vertical opening, then it will still be necessary to choose the mechanics of the lifting mechanism. Such models are already to the category of cheap not to attribute. There are three options for opening:

• rollers;
• cable;
• chain.

Rollers are the most convenient. Smooth running, little effort that has to be applied. The rollers are made of metal, which well tolerates overheating, but over time they can wear off. This will make opening more problematic.

The mechanisms may utilize chain or rope Chains are more reliable, but are noisier. The rope glides silently, but when heated, it can stretch more strongly, which can complicate the process. It is impossible to say definitively that any of the systems is more reliable or less reliable. What is known for sure is that the chain makes more noise. If this is critical for you, choose a rope or roller mechanism.

Glass: double, triple or mirror glass

Fireplace firebox of the closed type has a large area of glass. If there is single glass, it gives off a lot of heat. To reduce the amount of heat that penetrates through the glass, put double or triple. The second option – with mirror spraying. Heat is reflected inside the firebox, which increases the temperature, and this leads to a more complete combustion of fuel.

Spraying is more effective, but it is also more expensive. Double glazing comes out cheaper, though it performs worse. But double or triple pane glass contributes to the fact that it stays cleaner longer. Although it depends more on how well the self-cleaning system is done.

Fireplace firebox for heating: peculiarities of choice

When choosing a fireplace firebox for heating, it is necessary to pay attention to the indicators that increase the life of the equipment. After all, with active use, the resource is quickly exhausted and it should be large enough. The second point is the cost of heating. The unit should effectively use fuel, then heating will be economical.

1. Pay attention to the wall thickness and weight. The greater the wall thickness, the longer the service life. The higher the density and weight, the higher the thermal inertness of the firebox. This is important when combustion comes to an end. You won’t be putting wood in the firebox all the time. At night, the firebox is left to burn out. Here a large thermal inertia and will play a role, heated walls of the furnace will give heat, maintaining combustion and temperature in the house. The second positive moment of a large inertia, hot furnace stabilizes the draft, condensation does not form and serves the equipment longer.

   

2. The quality of connection of the parts of the firebox. There are several ways of assembling cast iron fireplace fireboxes:
   1. One-piece. The entire firebox is cast as a single piece. Very airtight, but also the most expensive option.
   2. Sealed assembly. Seams between parts are smeared with sealant, then bolted together. The cheapest option. Depends on the human factor. It is important how evenly and without gaps the sealant is laid. The second disadvantage, the shelf life of the sealant.
   3. Assembly with the help of ceramic cord. Parts are laid with a sealing cord, then tightened with bolts. There is a groove for the cord, so that its laying is less dependent on a person. But the reliability of the seal and its durability, depend on the characteristics of the cord, and good cords are expensive.
3. Chimney diameter. To save fuel, it is better if the chimney has a small cross-section, slower moving air, slower and more complete combustion of fuel. Proper glass cleaning system. These are not just slits above the glass for airflow. It’s a metal maze where air is first launched into the firebox and then travels along the glass. It’s just that the slits either don’t work and the glass smokes (when the openings are almost closed) or the air supply is too active, causing the wood to burn quickly. This is not economical at all, which when using the fireplace for heating is very important.

   

4. Afterburning system. This is the supply of heated air to the top of the firebox. Then at the top there is a secondary ignition of combustible gases, on which the wood has decomposed. They give off more heat during combustion than the wood itself. So their afterburning really gives more heat and allows you to save firewood.

Of course, you want the fireplace firebox to be beautiful. But, when using it as a heating element, beauty is not the main thing. Much more important are the quality characteristics.

How do expensive cast iron fireplace fireboxes differ from cheap ones?

As already said, the fireplace firebox can be cheap, medium-priced and expensive. With external similarities, there are certain differences. And they are not in the external data, although this is also present. In the high price category, other materials are used. The difference is this.

It seems a little, but these little things affect the work of the fireplace to a great extent. If you manage to find a budget model with good sealing, you can safely take it. If not, look in the middle price range. There is more likely to find the required.

Additionally, we advise you to read the article “Manufacturers of fireplace fireboxes: which are the best?”.