What is BS EN 13203-2 about?
BS EN 13203 discusses gas-fired domestic appliances producing hot water. BS EN 13203-2 is applicable to gas-fired appliances producing domestic hot water. BS EN 13203-2 applies to both instantaneous and storage tank appliances; waters-heaters and combination boilers that have:
- A heat input not exceeding 400 kW
- A hot water storage tank capacity (if any) not exceeding 2000 l
BS EN 13203-2 sets out a method for assessing the energy performance of the appliances.
Who is BS EN 13203-2 for?
BS EN 13203-2 on gas-fired domestic appliances producing hot water (assessment of energy) is useful for:
- Gas appliances manufacturers
- Quality control personnel
Why should you use BS EN 13203-2?
Apart from preventing greenhouse emissions and conserving energy, energy-efficient gas appliances producing hot water also help your customer save money by reducing their energy bills at home.
BS EN 13203-2 sets out a method for assessing the energy performance of the appliances. BS EN 13203-2 defines several daily load profiles for each domestic hot water use, kitchen, shower, bath, and a combination of these, together with corresponding test procedures, enabling the energy performances of different gas-fired appliances to be compared and matched to the needs of the user.
What’s changed since the last update?
BS EN 13203-2:2018 supersedes BS EN 13203-2:2015, which is withdrawn. BS EN 13203-2:2018 includes some technical changes with respect to BS EN 13203-2:2015. These include:
- Improvement of the test conditions (e.g., water supply, initial adjustment of the appliance)
- Addition of further load profile XS for small appliances
- Addition of new clause dealing with mixed water at 40°C (V40) for storage water heaters and corresponding complement to Annex ZA (informative)
- Addition of new Annex C (informative) dealing with the declaration of the maximum load profile

