Wood Burners

Origins of the Wood Burning Stove

Wood burning stoves are essentially a solution to the main problems of open fireplaces; principally thermal inefficiency and smoke. By fully enclosing the fire in a metal box (the stove) it is possible to control the air flow and hence improve the combustion rate and overall efficiency plus reduce the amount of smoke produced and redirect that which is produced directly to the outside.

An easy way to convert an existing fireplace to a wood burning stove is by fitting a “fireplace insert”. Fireplace inserts (also known as fireplace heaters) are generally little more than a specially constructed metal box that is fitted inside an existing fireplace and chimney. Though still not up to the standards of a modern wood burning stove, a fireplace insert nevertheless produces much less smoke and requires less fuel than traditional fireplaces since it is more efficient.

Fireplace inserts come in all shapes and sizes, and like much else in this field, can also be called different things, for example “cassette fire” or “fire box”. A popular manufacturer of such fireboxes is Jetmaster Fireplaces who offer a large range of fabulous looking fire boxes that deliver both the radiant heat one normally expects from a fireplace plus an additional boost of convected heat from a cleverly integrated convection system. An even simpler alternative that appeals to some is a fireplace heat exchanger.

Moving on from standard fireplaces, both open and closed, the modern wood burning stove is popularly thought to derive from the Franklin stove (named after the famous inventor and Founding Father of the USA Benjamin Franklin) which was an enclosed cast iron box with baffles to control the air flow and a metal pipe to conduct smoke and hot exhaust from the firebox through the house (thereby further dissipating heat within the home) and venting it to the outside.

Contemporaries credited the Franklin stove as being capable of outputting twice the amount of heat from one third the wood consumed as compared to a standard fireplace. This gives some idea of the superior capabilities of the wood burning stove over other forms of heating even though the traditional Franklin stove can claim only 20-30% total efficiency; in the modern era some wood burning stoves are able to attain ratings of 80% overall efficiency.

The Main Types of Wood Burning Stove

Modern wood burners take one of three main forms, putting aside the fireplace insert or firebox design mentioned above. Simple (and cheap) box wood burning stoves hold the fire within a metal box, but the door is not airtight.

Airtight wood burners utilise a fully sealed box with an airtight door. An airtight wood burning stove offers the ability to control the rate of combustion, and accordingly heat output, by either manual or automated means, increasing or decreasing airflow to the fire. Clearly controlling airflow is not an option if the burner is not airtight.

Wood pellet stoves as the name suggests accept specially manufactured wood pellets (or sometimes suitably sized and graded wood chips) very often also incorporate electronic regulator mechanisms. Wood pellets are created from pulped and pressed wood, often recycled from waste wood pulp and sawdust, and have the advantage that they burn at a regular temperature and predictable speed.

Pellet wood stoves may also be fitted with fuel hoppers that automatically supply fuel as determined by an electronic timer and sensor. Wood pellet burners are gaining popularity due to their ease of use and automation, but also because they are highly efficient and ecologically sound, recycling otherwise waste products from an already renewable fuel source - wood. They also attract grants for installation and other incentives and like all other types of wood biomass, wood pellet are specifically exempt from the Climate Change Levy (a tax on energy use aimed at limiting carbon dioxide pollution).

Each of these three basic designs may then be considered in the context of their intended application: room heaters (or space heating stoves) and cookers. And each of these further two subcategories further subdivides into those that incorporate a boiler and those that don’t. There are of course some wood burners that are in fact just wood burning boilers and provide no space heating or cooking capability at all, but this is getting complicated enough already.

So how to select which woodburner is right for you? Well a lot depends on your expectations as regards the process of installation of your wood burning stove and on the specific applications you have in mind for your wood burner, which we shall now skim through.

How to Use Domestic Wood Burners

If you’re looking for space heating then a room heater is what you should look for. These are typically highly controllable and provide direct warmth through radiant heat as well as convecting heat throughout the room and into the rest of the house. The range of sizes, designs, heat capacities and is huge so you’re bound to find something just right for you. Many also have integral back boilers which can heat up to ten radiators and supply ample hot water, so these can provide a full scale domestic heating system as well as being an attractive focal point in any household.

If, as is true for many people, the kitchen is the hub of your household then consider installing a wood burner in the form of a solid fuel cooker which introduces both classic good looks and the ultimate cooking environment. Wood burning kitchen ranges cook food to perfection and keep the kitchen nice and cosy; like room heaters, some models also offer full central heating plus continuous domestic hot water. A solid fuel cooker is simplicity itself; a controllable continuous fire inside a thick cast iron case which retains the heat. Unlike a gas or electric cooker, food is gently and evenly cooked and doesn’t dry out thereby keeping all the full natural flavour.

One thing that many people want to do is both enjoy the experience of a real fire and/or traditional kitchen range and to use this extra heat to fully or partially take the load of providing the main domestic heating and hot water. So when you are not using your wood burner, the central heating system operates as normal using the existing gas boiler for example, but when the fire is lit then the solid fuel system automatically takes over and provides heat and hot water at no extra cost. This is accomplished as follows.

A solid fuel cooker or roomheater fitted with a back boiler is linked to an existing boiler in such a way that either or both may contribute to the heating and hot water. The existing central heating boiler is left in situ and continues to service the system as necessary - either to top up the output from the wood burning stove or if that is turned off to provide all heat and hot water. You can also configure this system so that the wood burner heats either the hot water cylinder or the radiators or both.

This type of system is sometimes called “Link-Up” and is best used with open vented system. It is more problematic to integrate solid fuel boilers with combi or condensing boilers which operate using pressurised systems, but this can be done using a device for combining feeds from mains pressure combi boilers with open vented systems (the Grant CombiSOL for example).

Standalone wood boilers provide domestic hot water and central heating and can be sized to suit a small cottage through to a very large house. There are two main types of wood burning boiler: gravity feed and batch feed.

Gravity fed wood burning boilers typically incorporate an automatic biomass fuel hopper positioned above the firebox which can supply fuel for several days (depending on demand of course). The biomass fuel (usually wood pellets) is dropped into to the fire as required and an integral thermostatically controlled fan assists combustion in order to give a rapid response to demand.

Batch feed wood boilers are ‘hand fired’ meaning you have to load the fuel yourself, by hand, and consequently they tend to need more frequent refuelling than gravity feed wood boilers. Batch fed wood boilers are on the whole though less expensive and not dependent on an electrical supply, so are not susceptible to a power failure, which may be a consideration for you.

Makes of Wood Burning Stove

Now we’ve covered the main reasons why you might want to install a wood burning stove, let’s take a quick look at specific makes and brands.

The list of manufacturers and retailers of wood burners is seemingly endless, but here are some better known suppliers to start with. First up are makers of wood burning room heaters.

Woodwarm Stoves have been around for three decades and offer a good selection of wood burning space heaters including larger models that include wood burning back boilers.

Parkray specialise in insert fires that incorporate a back boiler. Their target market is people looking for a complete replacement for an existing heating system (or installing heating into a new build). Their own introduction puts it perfectly: “An elegant fire replaces your chunky old boiler, running up to 10 radiators. You get instant heat, lower emissions, and a gorgeous new centrepiece for your living room.”

Charnwood Stoves (also known as A J Wells & Sons Ltd) have been building a complete range of room heater stoves for some 25 years and also have a neat 3D stove selector tool on their website.

When is comes to solid fuel cookers then the names Aga, Rayburn and Esse all spring readily to mind. These three in fact manufacturer the whole range of solid fuel appliances, not just cookers, but are best known for their stylish, distinctive range cookers. As a side note, Rayburn has been owned by Aga for some time now and is often called Aga-Rayburn (you will find these cookers on both the Aga and Rayburn sites).

Needless to say, all these manufacturers of cooker provide variants with a wood boiler to supply central heating and hot water. Hopefully this article has covered enough of the basics for anyone looking for an overview of how to install a wood burning stove. For more information follow the links to any of the related topics/posts below.