ERP for water heaters – what you need to know

heatraeThis September the European Union’s Energy Labelling Framework Directive finally came into force for water heaters. Here technical support manager at Heatrae Sadia, Alan Clarke, tells us more.

The Energy Labelling Regulations for water heaters came into force on 26 September 2015. Part of the legislation commonly referred to as the Energy-related Products (ErP) Directive, it means that water heaters with outputs of up to 70kW and indirect storage tanks with capacities of up to 500 litres now have to come with an efficiency rating, initially from A to G.

Those that have looked at the ratings of various space heaters may have noticed that while boilers have been awarded A ratings, in reality ratings for water heaters and storage tanks range from A to D. But why?

To begin with, indirect storage tanks will be rated according to their heat loss. Each efficiency band has a maximum and minimum heat loss related to capacity, and so to achieve a high efficiency banding the insulation of the tank is key.

While manufacturers are continually innovating to improve insulation, the UK requirement to factory fit a Temperature Relief Valve to an unvented cylinder poses a key challenge. Products that insulate these features as far as is possible will have a lower heat loss, and thus a higher efficiency banding.

Meanwhile, direct electric unvented water heaters face separate challenges. Electrically heated products are assessed against a “load profile” – a series of hot water tapping profiles that reflect the usage of units of different capacity. As electricity is viewed as a carbon intensive fuel, the efficiency of an electric unit is divided by a “fuel factor”, reducing its apparent efficiency. As a result, a direct electric water heater may have a lower efficiency than an equivalent size indirectly heated unit.

And so, when deciding which water heater is best in terms of energy efficiency – and justifying that recommendation to customers – it is important to look beyond just the energy label. Every unit will be supplied with additional performance and efficiency parameters via a ‘technical fiche’, which must be included on manufacturer websites and in installation instructions supplied with the product.

In addition, there is a great deal of help and information available from manufacturers. For instance, installers who are unsure as to how to compare unvented cylinders with the same energy banding can access expert advice by contacting the Heatrae Sadia technical helpline.

For more information, visit or call 01603 420 220.

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