Over the last few years I’ve noticed that customers looking for a woodburner to use in a smoke free zone sometimes get confused about whether they should be looking at cleanburn stoves or DEFRA stoves. This post explains the differences between them.
At their most basic, woodburners are little more than enclosures for fires, offering huge improvements in efficiency over an open fire. Controllability is based on adjusting the amount of fresh air allowed into the stove through air spinners or sliders – a fire with a greater oxygen supply burns faster and gives out more heat. Over the years a variety of cleanburn technologies have been developed to further improve the performance of woodburners.
Cleanburn is the general name given to technologies which make wood stoves burn more efficiently, thereby cleaning up their emissions. The most common clean burn technologies seen in woodburners are secondary and tertiary burn, but there are also some stoves with catalytic combustion systems. Advantages of cleanburn stoves include reduced fuel costs due to improved efficiency, reduced emissions of pollutants into the atmosphere and incredible flame patterns.
The DEFRA Standard
The Department for Environment, Food and Rural Affairs, or DEFRA, is the government department responsible for enforcing the Clean Air Acts of 1956 and 1968. DEFRA has a wide-ranging remit which includes maintaining and improving air quality throughout the UK. One of the ways they do this is to set standards for acceptable emissions from appliances such as wood burning stoves. DEFRA are concerned with the amount of carbon monoxide given off by a stove as well as the fine particulate matter which causes sooty smog.
In order for a stove to become DEFRA approved, the manufacturer must submit the stove to a stringent independent testing process to ensure it complies with DEFRA standards. A wood stove may be capable of meeting DEFRA standards without actually having been tested for DEFRA approval. The testing process is costly to stove manufacturers, but they are responding to increasing demand from consumers in urban areas by both having existing models certified and developing cleaner burning stoves.
Do You Need a DEFRA Stove?
All DEFRA stoves are clean burning, but not all cleanburn stoves are DEFRA Approved. If you want to install a woodburner in a smoke control area, you need to look at DEFRA stoves. If you are interested in buying a cleanburn stove for environmental reasons, for example to help manage your carbon footprint, then look for features such as secondary burn, tertiary burn or catalytic combustion.