Wood stoves are much more efficient than open fires and almost as nice to sit near on a cold winter evening. Many have glass doors enabling you to see the fire itself, and some give you hot water, too. At a pinch, you can even cook on the flat tops of some models. Using wood for fuel in this way is carbon-neutral, releasing the same CO2 that became stored in it as it grew: provided more wood is grown to replace any that is burned for fuel, the whole process cancels itself out. Wood ash is an important source of lye to those who are interested in soap-making, and can be put on gardens where it adds potassium and raises pH levels. Burning dry wood fast and hot creates relatively little pollution, whereas burning it slowly or when damp creates more.
There are hundreds of different wood stove designs available ranging from extremely ornate ‘antique’ styles to very plain ‘modern’ ones. Some have flat tops, some have a canopy, some have windows and some don’t. Some are intended to just heat a small room, others are ‘central heating’ wood stoves that direct part of the heat into the room and divert the rest to a back boiler, thus generating hot water. Whatever your living space, there’s bound to be a wood stove that will look good in it.
If you have an existing chimney, installing a wood stove usually means putting a liner inside it. For nice straight chimneys this can made up of sections of jointed metal pipe, which can be either single or double skinned. A double skin is more airtight and lasts longer than a single skin. For chimneys that aren’t perfectly straight, a flexible non-flammable liner is used instead. Either way, chimneys should be swept at least once a year and twice if they are in heavy use. Otherwise, creosote (a by-product of inefficient combustion) builds up on the walls of the chimney to become a fire hazard, and the heat generated by the wood stove beneath can set the whole thing alight, causing a chimney fire. Creosote builds up gradually over time because fires burn less efficiently when they are just getting started, but can accumulate very rapidly if you burn unseasoned or damp wood.
As with an open fire, the hot air vanishing up the chimney has to come from somewhere. While this is usually the room in which the wood stove has been placed, which in turn means other rooms in the house may be becoming colder as the stove heats up, some models now bring in their own air supply from outside making them much more efficient. But the real key to the improved efficiency of wood stoves is the way in which they control the air supply. Vents, usually mounted near the door, can be opened or closed to increase or decrease the airflow through the fire. There is often also a ‘damper’ mounted on the chimney pipes, although on some ‘airtight’ installations (see below) this isn’t needed. A damper is an external handle which turns a disc mounted inside the flue to restrict the flow of air up the chimney.
‘Airtight’ wood stoves
On ‘airtight’ wood stove models you can not only control the amount of air that’s allowed to flow through the fire, you can even shut if off completely – which is, incidentally, one way of stopping a chimney fire. On less efficient wood stoves the controls are unable to do this. ‘Airtight’ control means a fire can be regulated to burn far more efficiently, and far hotter – up to 200°C hotter – than a conventional open fire. Some wood stove designs direct the internal flow of air so that most of the smoke is burned, as well as sending a hot air flow downwards over the door windows which helps to keep them clean.
Cleaning wood stove windows
Even with the help of a directed airflow, all wood stove windows will become sooty over time. To get rid of this there’s no need to bother with costly and toxic cleaners – just dampen a scrap of newspaper with some vinegar or lemon juice, and get rubbing. It doesn’t usually take more than five minutes if done regularly, and will warm you up nicely in the process!
Wood stove costs
Wood stoves are usually rated at their kW output when burning an ideally-packed load of dry wood. Stove size, obviously enough, has a direct bearing on the amount of wood they hold and therefore their kW output. Smaller wood stoves may be rated at around 4kW, while a big stove could be rated between 12-16kW or even more for a central heating model. While the quality of manufacture varies, key things to look for are wall thickness and air control efficiency. Wood stove prices can range from £250 for a small (4+ kW) stove to well over £1500 for something larger.