This document is applicable to gas-fired appliances producing domestic hot water. It 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 2 000 l. In the case of combination boilers, with or without storage tank, domestic hot water production is integrated or coupled, the whole being marketed as a single unit. The water heaters covered by the present standard are considered "conventional water heaters" as defined by the Transitional Methods (Commission Communication 2014/C 207/03) then in the calculation formula for the Annual Electricity Consumption (AEC), Qcor is equal to zero. In case of the boiler is equipped with an internal or external Passive Flue Heat Recovery Device (PFHRD), the boiler efficiency can be assessed by applying EN 13203-2:2022 in combination with EN 13203-7:2022. In case of a PFHRD, where the technology has the ability to recover energy out of flue gasses during central heating production to be able to preheat the domestic hot water (indirect contribution), to assess this indirect contribution EN 13203-7:2022 applies. EN 13203-2:2022 is applicable for measuring and calculating the direct efficiency (direct contribution) while combining the measuring results of EN 13203-7:2022 the overall efficiency (direct and indirect) can be calculated. EN 13203-1:2015 sets out in qualitative and quantitative terms the performance in delivery of domestic hot water for a selected variety of uses. It also gives a system for presenting the information to the user. The present document sets out a method for assessing the energy performance of the appliances. It specifies a few 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. Where other technologies are combined with a gas-fired boiler or a water heater to produce domestic hot water, specific parts of EN 13203 apply.