NF D35-337:2017 Heating - Gas - Gas-fired central heating boiler of useful output not exceeding 70 kW designed to be connected to a mechanical installation for the evacuation of the combustion products
2017NF D35-337:2017 Heating - Gas - Gas-fired central heating boiler of useful output not exceeding 70 kW designed to be connected to a mechanical installation for the evacuation of the combustion products
2001NF D35-337:2001 Heating - Gas - Liquid fuel, solid fuel - Gas-fired central heating boilers of heat output not exceeding 70 kW designed to be connected to a mechanical installation for the evacuation of the combustion products.