It is often hard to distinguish between one woodburning stove and another at face value. But behind the stylish façade of a modern appliance there are a few key factors to consider before making your decision.
This calculator should give you a very rough idea of the output required for the space you are planning to heat. However, a professional installer will have the skills to size an appliance to a much greater degree of accuracy. In addition to room size, the following must be considered when “sizing” an appliance:
• Rate of refuelling • Temperature requirements • Household insulation
• Appliance efficiency
When you are in the showroom, you may find that some woodburning stoves quote net efficiency while others quote a gross figure. Arguably, the gross figure gives a more realistic representation of an stove’s performance. As a guide, to convert to ‘gross’ simply multiply the ‘net’ figure by 0.91 (for wood burning appliances) or 0.98 (for solid mineral fuel burning appliances).
The efficiency of an woodburning stove is roughly based on its design. Traditional open fires will display the lowest efficiency figures, often well below 50% (gross). Closed appliances such as room heaters and stoves are far more efficient, with a typical gross efficiency of up to (and in some cases exceeding) 80%.
Another high efficiency solution is the pellet stove. This appliance is fed with wood pellets (see below) via a storage hopper. These appliances can operate at efficiencies over 80% (gross).
Firewood – If sourcing your own firewood, ensure that you “season” it to a point where moisture content is less than 25%. If buying firewood from your supplier, politely ask them to prove that the moisture content is consistent with the figure they advertise.
Avoid burning treated wood at all costs. It can damage the appliance, but more importantly your health. Following the guidance above will ensure that your wood burner stays healthy and works well for many years. Most firewood stoves can burn wood briquettes as well (but always check with the manufacturer first).
Pellets (wood) – Pellet stoves are designed to be super-efficient at converting fuel into useful heat. These stoves are capable of operating for many hours without refuelling, as an automatic feed from a storage hopper supplies pellets. The pellets themselves are a clean heating solution and require less storage space than conventional wood logs.
When considering your first or replacement wood burning stove, check with your home insurance provider about their requirements. In order for your installation to be deemed legal, you will need to have your stove installed by either a registered installer from a competent person scheme (such as HETAS) or the installation has to be signed off by the local area Building Control. Speak to your home insurer for more details.
About the author: Laurence Jones was marketing support officer at HETAS