Important Announcement
GASTEC at CRE (GaC)
Important GaC announcement
We have had several questions regarding the efficiencies of wood-burning appliances and products.
Trading Standards legislation and Building Regulations are very clear on this. Manufacturers must declare an overall efficiency (as reported by an independent, third party, appropriately accredited, test laboratory) for conversion of energy in the fuel (ie wood) to hot water. This can be either based upon:-
OR
Manufacturers must state this basis in ALL of their literature. By way of example:-
Most reputable test laboratories report on both the Gross and the Net CV basis which is duly measured for each batch of fuel. Where test laboratories do not report this distinction, the following approximate conversion can be used:-
Gross = 0.91 x Net
(this is a figure based upon our considerable experience and research carried out by colleagues & others)
For the avoidance of any doubt, manufacturers must not quote combustion efficiency. This figure is usually above 99% (for wood) and is, effectively, meaningless.
We have had several questions regarding the efficiencies of wood-burning appliances and products.
Trading Standards legislation and Building Regulations are very clear on this. Manufacturers must declare an overall efficiency (as reported by an independent, third party, appropriately accredited, test laboratory) for conversion of energy in the fuel (ie wood) to hot water. This can be either based upon:-
- The Net calorific value (or Lower Calorific Value) of the wood, as measured
OR
- The Gross calorific value (or Higher Calorific Value) of the wood, as measured
Manufacturers must state this basis in ALL of their literature. By way of example:-
This Stove is 74.0% efficient
(based upon the Net Calorific Value of the wood fuel used)
Most reputable test laboratories report on both the Gross and the Net CV basis which is duly measured for each batch of fuel. Where test laboratories do not report this distinction, the following approximate conversion can be used:-
Gross = 0.91 x Net
(this is a figure based upon our considerable experience and research carried out by colleagues & others)
For the avoidance of any doubt, manufacturers must not quote combustion efficiency. This figure is usually above 99% (for wood) and is, effectively, meaningless.
