Rated heat output and rated heat input of combustion appliances
A combustion appliance is an apparatus where fuel is burned to generate heat for space heating, water heating, cooking or other similar purpose.
According to Approved document J, Combustion appliances and fuel storage systems:
The rated heat input (or ‘rated input’) for a gas appliance is the maximum heat input rate at which it can be operated, as declared on the appliance data plate.
The heat input rate is the maximum rate of energy flow into an appliance, calculated as the rate of fuel flow to the appliance multiplied by either the fuel’s gross or net calorific value. Traditionally, the UK has used gross values, most European standards use net values. Thus for gas appliances it is now the norm to express this rating as a net value (kW (net))
The rated heat output for an oil appliance is the maximum declared energy output rate (kW) as declared on the appliance data plate.
The rated heat output for a solid fuel appliance is the manufacturer’s declared nominal energy output rate (kW) for the appliance. This may be different for different fuels.
[edit] Related articles on Designing Buildings Wiki
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Changing expectations around competence and compliance
New information sheet from CIAT.
Grenfell investigation files passed to CPS
Angela Rayner apologises on behalf of the British state.
Electrical contractors need to understand the practical implications.
The real barrier to getting more value from digital technology.
Your guide to The Construction Reset at UKCW Birmingham.
Accommodating the Victorian and Edwardian working woman. Book review.
Rethinking passive fire protection in design
PFP demands the same level of design rigour as structure or services.
38% of Gen Zs feel safe when a fire door is wedged open.
Stunning images from around the world
Shortlist for CIOB’s Art of Building photography competition.
Guidance for conversion of traditional pre-1919 stone buildings.
Industrial heritage in the Ruhr
A marked difference to the fate of industrial landscapes in the UK.
Communities will be able to build their own clean energy.

















