ErP for water heaters - what you need to know

This September saw a watershed moment - the European Union's ErP legislation finally came into force for water heaters. But while a great deal has been written about the regulations, the energy efficiency bandings unveiled for water heaters could benefit from further explanation. Here technical support manager at Heatrae Sadia, Alan Clarke, tells us more.

As installers know, what is commonly referred to as the Energy-related Products (ErP) Regulations for water heaters came into force on 26 September 2015.

ErP is in fact two Directives: The Ecodesign Requirements for Energy Related Products Framework Directive and The Energy Labelling Framework Directive. These are enacted by Regulations relating to various product types.

The Ecodesign Regulation for water heaters will mean water heaters that haven't met minimum efficiency requirements cannot be CE marked, so manufacturers will no longer be legally allowed to put products into the supply chain.

The Energy Labelling Regulation will mean all affected water heaters have to come with an efficiency rating, initially from A to G. This second part is particularly important for installers, as it will offer them and their customers a visible guide to how an appliance has been rated in energy efficiency tests.

When it comes to water heaters, different sizes and types will be affected in different ways.

Ecodesign affects water heaters with a rated output up to 400kW and indirectly heated storage tanks with a capacity of up to 2,000 litres.

However, only water heaters with outputs of up to 70kW and indirect storage tanks with capacities of up to 500 litres will be given an efficiency label. Indirectly heated storage tanks are rated according to their heat loss, while electrically heated products are rated against a series of hot water tapping patterns.

From September 26, it will be illegal for manufacturers to place products on the market that don't meet the regulations. While any stock in the supply chain can continue to be sold and installed, once it is gone it will be important for installers to understand what is legally available, especially when a homeowner wants a like-for-like replacement for a product that doesn't meet the new efficiency requirements.

As space and combi heater ErP regulations have come in at the same time as legislation for water heaters, savvy installers who have looked at the compliant products now available may have noticed that while boilers have been awarded an A rating, ratings for water heaters and storage tanks range from A to D.

As most gas registered installers will be working with indirect unvented hot water cylinders (storage tanks) we'll focus on the reasons for their ratings first.

Indirect storage tanks will be rated according to their heat loss. This is measured in watts rather than the kilowatt hours per 24 hours that installers will be familiar with. 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. Manufacturers are continually innovating to improve insulation, with the best quality cylinders featuring a thick layer of high-performance polyurethane foam to fill the space between the inner vessel and casing.

A challenge for water heaters is the UK requirement to factory fit a Temperature Relief Valve to an unvented cylinder. Any feature that is attached to the vessel and breaches the insulation will be an area of increased heat loss, this valve being one. Products that insulate these features as far as is possible will have a lower heat loss and thus a higher efficiency banding.

Installers who work with direct electric unvented water heaters should also be aware of separate challenges that these products face. 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.

UK manufacturers and legislators have made efforts to try and change this point of view - pointing towards the multitude of renewable energy sources used to generate electricity. However, the EU has stayed its course. As a result, a direct electric water heater will have a lower efficiency than an equivalent size indirectly heated unit.

For installers who are deciding which water heater is best in terms of energy efficiency - and justifying that recommendation to their 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.

Ultimately, by understanding the differences in the way different types of water heater are rated and how that affects their energy efficiency band, installers will be better equipped to answer any questions from their customers and continue specifying the best heating system for the job at hand.

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