The Technology

Forget everything you may have thought about wood burning. Many of us may have had experiences of open log fires in our childhood or in other people's houses. They were dirty and smelly. They are difficult to light and as soon as the wind blew in the wrong direction to smoke would come into the room and choke everyone. Most of the heat went up the chimney and it just looked like an accident waiting to happen. You'd be crazy to want that, right? Right.

However, in Scandinavia they have been investing in Wood Burning Technology for decades. Obviously they have a lot of trees and some of the population is not connected to grid supplies of electricity or gas. Hence there was a big market for clean burning, modern, hi-tech, wood burning equipment. But let us get one thing straight - the "open fire" is neither practical nor healthy. You cannot control the rate of burn and all the heat goes up the chimney.

What you need is a wood burning stove. It will need one-third the wood of an open fire and be about 70% efficient. Even better than that - the Ceramic stoves (or "Kachelofens") are over 90% efficient. They are lit once a day and the stove then stays hot for a long time. A small home can benefit from a stove with a back-boiler to heat water for radiators. Larger houses can use a large water cylinder to store the heat from a stove working once a day.

Many pellet stoves and boilers are now self-igniting. They have a hopper at the top which you fill every few days or weeks. Wood pellet appliances can easily be 'turned down' because (unlike log stoves) the fuel and air supply can be better controlled. Efficiency can reach 90% and emissions are very low. The key to a 'clean burn' is high temperature. A clean burn means no harmful emissions. Wood pellet stoves use 0.5 to 1.5kg per hour.

Clean-burning wood should emit virtually no sulphur dioxide and very low levels of nitrous oxides (which are typically found in industrial smoke). It should also emit very low amounts of smoke particulates. Many wood-fire appliances are now certified for operation in 'smoke-free' zones.

Costs and Grants

A log stove could only cost £500 GBP to £1000 GBP so is comparable to an A Rated Condensing Gas Boiler. Pellet stoves cost between £1500 GBP to £2500 GBP. A £600 GBP grant is currently available (2007). Installation costs could double these costs.  Log boilers can cost around £4000 but could require a water storage tank, flue and installation pushing the total cost up to £7000 GBP.

Then there are automated pellet boilers. The Boiler alone could cost you £6000 GBP to £8000 GBP. With Installation this could be £11000 GBP to £12000 GBP. Wood fired central heating boilers can be eligible for a £1500 GBP grant from the Low Carbon Buildings Programme (see web address on this page). To give a specific example: the Treco wood pellet boiler that would heat a 5 bedroom house would cost £3890 and qualify for a 30% grant.

The fuel actually works out cheaper than gas, oil or coal if you buy in bulk. So you will need some storage space! If you only buy one 15kg bag of pellets then this will cost you £3 to £4.