Fireplace insert: types, parameters, choice

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

Which fireplace insert is better: open or closed

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

A closed fireplace insert is also made of metal, but differs in that it is airtight – it has a tightly fitting door that separates the fireplace from the room. In addition to the appearance, there are many more features. They will help you make a choice.

Open fireplace inserts

When we remember the fireplace, a picture arises: a hearth, crackling firewood, dancing flames. Everything is so, but let’s appreciate all the charms of such a heater:

• Free burning – a large consumption of firewood. The efficiency of open furnaces is only about 10-15%. This is despite the fact that it is done correctly, has a well-functioning chimney. That is, only a tenth of the heat received from burning firewood goes into the room. The rest just goes down the drain.
• Open fire is beautiful. Yes, but the combustion cannot be controlled. Firewood always burns “at full power”.
  

• An open firebox – soot flies not only into the chimney, but also into the room. After a couple of years of periodic use, the ceiling and walls will be covered with a gray coating. Don’t believe? Remove an object from the wall, evaluate the difference in color.
• Fireplaces with an open firebox are usually fenced off with protective screens. They prevent the possibility of coal getting outside the fireproof zone. But if the screen is forgotten to be installed or it has fallen, a fire may occur.
• A non-working fireplace is an excellent device for extracting heat. There is no need to ventilate the room, as the chimney draws air very well. And you can’t block it with a gate – there must be a hole in it. It is necessary for safety – so that the thrust does not overlap. To warm up a room with a non-working fireplace to normal temperature, you need a solid supply of power.

So, if you need a fireplace only for aesthetics, then an open fireplace insert will do. But only you should be aware of all the accompanying phenomena that you will have to face.

Closed fireboxes

Closed furnaces appeared not so long ago. They are more convenient, economical and safe. Some models have such large glazing that they allow you to admire the fire from almost anywhere. If you also want to listen to the crackling of firewood, you can open the door. These are not all the benefits. Here are the rest:

• Efficiency is about 75-85%, firewood is bunkered much less.
• Sealed door allows you to adjust the intensity of combustion.
• Cinders and soot can enter the room only with a poorly functioning chimney.
  

• It is safer, since the door does not allow coals to get on the floor.
• An extinguished fireplace does not draw out heat – the door is sealed.

In fact, a fireplace insert is one of the subspecies of a heating stove. It is distinguished by a wide door, the format of the furnace – wide and shallow, the shape of the vault. But aesthetically, they are much more attractive than standard stoves. Still, the fire is a beautiful sight. A fireplace with a closed firebox allows them to admire with maximum comfort.

As a conclusion, it is worth saying that a closed-type fireplace insert is good as a decorative element. But it can be used as part of the heating system. There are fireplace inserts with a water register – for connecting heating radiators. This, of course, is an option for an amateur, but also a viable one. It’s just that when choosing “for beauty”, they rely more on safety and appearance. When choosing “for heating”, albeit additional, they look more at performance characteristics, relegating beauty to the background.

Cast iron or steel

The fireplace insert can be steel or cast iron. In general, disputes about which is better – cast iron or steel for fireplaces and stoves – have been going on for a long time. And there is no single answer. Each option is ambiguous, each has pros and cons. Let’s list them:

• Cast iron fireboxes weigh more and 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 – after the firewood burns out, it will be warmer longer.
• The low weight of steel options has its advantages – they can be placed on any floor without any problems, without recalculating the load. If the total weight of the structure of the firebox + portal is more than 200 kg, it is necessary to strengthen the floor. If the ceiling is concrete, everything is fine, but under the logs additional support is needed.
  

• Steel can be welded. This gives a huge scope for various designs. Cast iron is only cast, and the creation of new models is a long and complicated process. Therefore, cast iron models are more conservative. But the fireplace insert, most often, is hidden in the portal. So there is no need for special beauty – only quality.
• Steel, even thick and high-quality, burns through. To protect the walls from direct heating, they are covered with heat-resistant materials – they make a lining. This extends their service life, but depends on the quality of the material and the performance of the work. Cast iron walls can withstand fire for decades. No steel, even with a lining, will last thirty or forty years.
• A cast iron fireplace insert usually consists of several parts. They are hermetically sealed. But any connection is a risk. Steel furnaces are welded. The seam is also a weak point, but properly executed, it is quite reliable. However, often the destruction of metals begins with the seams.
  

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

We hope you were able to conclude for yourself which fireplace insert is better – made of steel or cast iron. Both options are not ideal, but cast iron is usually preferred. It is more durable, which is usually the decisive argument.

Types of fireplace inserts

Most of the models are attached to the wall – the portal protrudes from the plane of the wall. This method of installation can be considered traditional – this is how our ancestors did it. There is another technology – built-in fireplaces. This is when a wall or wall is specially modified or built, a chimney and all other elements of the system are laid in them. Such fireboxes are special – for installation in a corner (as in the photo below on the left). Their body has the shape of a trapezoid, tapering from the door. When mounted directly to the wall, the housing is rectangular.

Corner fireboxes are good because they take up space that is the hardest to use. But the tapering shape of the firebox requires smaller firewood. Second moment. With an equal door width, the corner ones have a slightly lower thermal power – the volume of the combustion chamber is smaller. But the fireplace in the corner allows you to save on materials for the portal – there are already two walls. In general, also a good option.

Type of glazing

Fireplace inserts with straight, round or trapezoidal glass were the first to appear. Glass was necessarily enclosed in a metal frame, hinges – on the right or left. There are many such models now. Some even have the same design, but there are more modern forms. Accordingly, if the door opens to the right, they are called right-handed, if left – left-handed. If the glass is symmetrical, it is possible to choose which way the door will open.

Such models are attractive, but the review is still limited. Modern interiors dictate their own rules, and the presence of curved fire-resistant glass and transparent fire-resistant sealants made it possible to create more interesting models. In addition to the “regular” flat-door fireplaces, there are more interesting (and expensive) varieties:

• Tunnel (through). One fireplace for two rooms – built into the wall, heats adjacent rooms.
• Double-sided with L-shaped glazing. The flame can be admired from two sides. They can be right-handed or left-handed.
  

• Three-sided – with U-shaped glass. Only the back wall is closed.

But this is not all varieties. There are different ways to open the door: to the side on hinges or lifting up. A firebox with rising glass is called a guillotine. Such options are more expensive, but the fireplace may look like an open one – the door leaves up into the groove, which is arranged on top. They can work with both closed and open doors. Versions with hinged doors are more designed for closed door operation.

What to look for when choosing inexpensive fireplaces

Conventionally, all fireplace inserts can be divided into three categories: cheap, medium price range and expensive. The main point is not the manufacturer and his name, but the quality and technologies that are used. Miracles don’t happen. It is impossible to buy a cheap fireplace insert with the same performance as an expensive one. But there are better and worse models in every price range. And, at the same price, the quality can vary 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 cheap ones, carefully inspect the selected models.

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 must be even, without sags, cavities, etc. The quality of cast iron is checked by external inspection. The smoother the casting, the higher the quality. The wall thickness of the steel and cast iron firebox is also important. Especially on the vault, where the heat load is the highest. There should be a maximum thickness.

The tightness of the firebox

First and foremost, a fireplace insert must be airtight to work effectively. 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 air is supplied through the ash pan. Grooves are made under the door, which are blocked by movable shutters. Lever at the bottom or side. By opening and closing the air supply, we regulate the intensity of combustion. There may be several adjustments, but they all make sense if they allow you to completely shut off the flow. Check how well they fit, how securely they block air access.
  

• Door seal. Made from ceramic cord and goes around the perimeter without gaps. Not from below, not from two or three sides. The cord should be wide (go beyond the frame further) and soft. If it has lost its elasticity or is made flush with the groove in the new firebox, there will be no tightness.
• How the glass is pressed against the frame of the door. If the clamp is only with several holders, air will flow. Ideally, a metal corner that is pressed against the holders. And one more thing: the holders must be reliable, made of good metal (you won’t be able to bend them with your fingers).
• Glass sealing – around the entire perimeter between the glass and the door frame. Better the same ceramic cord, but flatter. The sealant is good, but the cord is better.
  

• Glass cleaning system. These are the holes at the top of the door frame above the glass. Air enters through them, it goes down, carrying soot and fumes. So the glass stays cleaner longer. Please note: the glass will still need to be cleaned occasionally.
• How to open a chimney damper. The cheapest is bolted, but also the most unreliable. If a bolted connection is selected, provide for access during installation – for repair and replacement of bolts / nuts.

As you can see, there are enough parameters and these are just the main ones. There is still beauty. If your 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 efficiency is important. It will be economical when the heat is extracted to the maximum. Therefore, we pay attention to the presence of a secondary air supply.

Usually air is supplied through the grate. He enters the firewood, they burn. More gases are produced during the process. For the most part, they are combustible and the heat of combustion is greater than the heat that we get when burning wood. If you set fire to these gases, the heat will be much more. To set fire to them, it is enough to add oxygen.

To do this, make holes in the back wall and in the upper part of the firebox. This is the secondary air supply – for afterburning gases. Air is supplied to the upper part of the furnace, it is mixed with hot gases. This mixture flares up, which provides additional heat. This process can be observed. When burning, a fire cap is formed in the upper part of the firebox. But once again we pay attention – this makes sense in a sealed furnace, where the supply of air (and the oxygen it contains) is normalized.

Features of guillotine fireplaces

If you are interested in a fireplace insert with vertical opening, then you will also need to choose the mechanics of the lifting mechanism. Such models cannot be attributed to the category of cheap ones – the mechanism itself is quite expensive. There are three opening options:

• videos;
• cable;
• chain.

Rollers are the best. Smooth running, little effort required. The rollers are made of metal that tolerates overheating well, but can wear out over time. This will make opening more problematic.

There is also a chain and cable that are pulled through a system of wheels and sprockets. The chain is more reliable, but noisier – it rings when moving. The cable slides silently, but when heated, it can stretch more, which can complicate the process. It cannot be said unequivocally that some of the systems are more reliable, and some are less. What is known for sure is that the chain makes more noise. If this is critical for you, choose a cable or roller mechanism.

Glass: double, triple or mirror

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

What’s better? Spraying is more efficient, but also more expensive. Double glass comes out cheaper, although it works worse. But double or triple glass helps keep it clean longer. Although, it depends more on how well the self-cleaning system is made.

Fireplace insert for heating: features of choice

When choosing a fireplace insert for heating, you need to pay attention to indicators that increase the life of the equipment. Indeed, with active use, the resource is quickly exhausted and it should be large enough. The second point is heating costs. The unit must use fuel efficiently, then heating will be economical.

1. Pay attention to wall thickness and weight. The thicker the walls, the longer the service life. The higher the density and mass, the higher the thermal inertia of the furnace. This is important when the burning comes to an end. You won’t be adding firewood all the time. At night, the firebox is left to burn out. This is where a large thermal inertia will play its role – the heated walls of the furnace will give off heat, maintaining combustion and the temperature in the house. The second positive moment of great inertia is that a hot furnace stabilizes draft, condensate does not form, and the equipment lasts longer.
   

2. The quality of the connection of the furnace parts. There are several ways to assemble cast iron fireplace inserts:
   1. Solid cast. The entire firebox is cast as a single unit without joints. Very airtight, but also the most expensive option.
   2. Sealant assembly. The seams between the parts are coated with sealant, then tightened with bolts. The cheapest option. Depends on the human factor. It is important how evenly and without gaps the sealant is laid. The second drawback is that the shelf life of the sealant is finite and not too long.
   3. Assembly with a 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 the 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 section – the air moves more slowly, the fuel burns more slowly and more completely.
   

4. Proper glass cleaning system. These are not just gaps above the glass for air supply. This is a metal labyrinth in which air is first launched into the furnace, and then goes along the glass. It’s just that the slots either do not work and the glass smokes (when the holes are almost closed) or air is supplied too actively, which leads to the rapid combustion of firewood. This is completely uneconomical, which is very important when using a fireplace for heating.
5. Afterburner system. This is the supply of heated air to the top of the furnace. Then at the top there is a secondary ignition of combustible gases into which the wood has decomposed. When burned, they release more heat than the wood itself. So afterburning them really gives more heat and saves firewood.

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

What is the difference between expensive cast iron fireplace inserts and cheap ones

As already mentioned, a fireplace insert can be cheap, mid-priced and expensive. While externally similar, there are certain differences. And they are not in external data, although this is also present. In the high price category, other materials are used. Here is the difference.

• The quality of the metal is higher.
• Better fitting parts. For example, backlash when closing doors. In cheap versions, the door must be lifted, pressed. In expensive ones it closes easily.
• Connection of parts of cast-iron furnaces. In cheap ones – sealant, then the screws are tightened at the attachment points. The expensive ones have o-rings installed, then the screws are tightened. The cord is much more expensive and more reliable.
  

• The degree of sealing of glass and doors. If in cheap ones you need to carefully monitor everything, in expensive ones it goes “by default”.
• Quality lining.
• Sophisticated shape of the furnace, higher efficiency (80-85% instead of 60-75%).
• Combustion air supply from outside. Moreover, for long-term burning, it does not go through the ash pan (in cheap models), but is fed from above. Therefore, expensive fireplace inserts often do not have an ash pan and they need to be cleaned once every 1-2 weeks, and not every day. Just a small pile of ash remains from the firewood. There are no coals and even no ash. Very little soft residue.
• Appearance

It seems a little, but these “little things” affect the operation of the fireplace to a large 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. It’s more likely to find what you want.

Additionally, we advise you to read the article “Manufacturers of fireplace inserts: which ones are better?”.