DHW Heat Pumps – Selection Criteria

What are domestic hot water heat pumps?

A heat pump works by extracting heat from the environment and using that energy to heat water. In the case of a domestic hot water heat pump, the environment the heat pump extracts heat from is typically the room it is installed – for example, a storage room, boiler room or larder.

They need some electricity to run, but because their heat output is higher than the electricity input, they are highly efficient, low carbon hot water heating systems.

For more details and a general overview of what these products are, please see our Product Guide. For heat pumps that provide space heating as well as hot water please see our pages for Heat pumps for space heating.

Introduction

This page details the selection criteria applied to domestic hot water heat pumps on toptenuk.org. A domestic hot water heat pump is a heating system solely dedicated to the production of hot water for direct use (i.e. not for space heating). Any fuel type (gas, oil, electricity etc.) can power these products, however for the time being; only electric heat pump type systems are considered in this list. Of these, only products that reach the minimum criteria specified below are displayed on the website.

Selection Criteria

The minimum criteria to be shown on toptenuk.org is shown in Table 1 which covers energy performance metrics.

Table 1: Current selection criteria for water heaters.

Criteria	Eligibility
Energy Measurement	Must be measured according to EN16147:2011
Energy Class	A+

Relevant Regulations & Standards

The following regulations were the basis for the above selection criteria for electric water heaters.

EN16147:2011

This standard details the testing requirements for electrically driven heat pumps for domestic hot water. Heat pumps must be tested using this to qualify for the topten website. This has been superseded by EN16147:2017 which is a revised version of this standard.

Glossary Average Efficiency

• Value (η_average) – Ratio between the useful energy provided by a heater and the energy required for its generation, expressed in %. For more information on how this is calculated see EU energy label regulation for water heaters.
• Standard for heat pumps with electrically driven compressors. Testing and requirements for marking of domestic hot water units; https://shop.bsigroup.com/ProductDetail/?pid=000000000030254905

Links

EU regulation for energy labelling of water heaters, hot water storage tanks and packages of water heater and solar device; https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02013R0812-20180426&qid=1603278322288