Selection Criteria

Air Source Heat Pumps (space heating)

A heat pump works by extracting heat from the environment and transferring that heat to your home. They need some electricity to run, but because their heat output is higher than the electricity input, they are highly efficient, low carbon heating systems

Introduction

This page details the criteria used to select air source heat pumps for toptenuk.org. The heat pumps displayed here are all able to supply heat for space heating or space heating and domestic hot water. Air-based distribution systems are not included in this list – only wet heating systems. Heat pumps which only supply domestic hot water only are covered in a separate category on the topten website, Domestic Hot Water Heat Pumps.

For space heating and domestic hot water heat pumps, only those that reach the minimum criteria specified below are displayed on the website. For more details on how they operate and things to look out for when purchasing one, please see our Product Guide.

Definition


ASHP (Air Source Heat Pump) 		Heat is collected from the air surrounding the device and the heat exchanged with a wet heating system. These are also called air-to-water heat pumps.

Selection Criteria

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

Table 1: Current selection criteria for air source heat pumps.

Criteria

Eligibility

Certification

MCS certified or equivalent


Product Type

Must be serial product (i.e. no prototypes/one-off systems)

Energy Measurement

Must be measured according to EN14825

MCS Seasonal Coefficient of Performance (SCOP)*

SCOP at 35°C ≥ 4.08

SCOP at 55°C ≥ 3.09

*SCOPs calculated using average climate conditions and design criteria defined by Commission Regulation (EU) No. 813/2013.

Relevant Regulations

The following regulations were the basis for the above selection criteria for heat pumps.

Terms/glossary

MCS

Microgeneration Certification Scheme is an industry-led quality assurance scheme, which demonstrates the quality and reliability of approved products. Heat pumps are tested to ensure they meet MCS standards. The scheme also certified installers.

Efficiency class at 35°C

Energy rating according the the energy label for space heating at 35°C

Efficiency class at 55°C

Energy rating according the the energy label for space heating at 55°C

Coefficient of Performance (COP)

The Coefficient of Performance (COP) - displayed as a number - is a term used to describe the efficiency of a heat pump. The number represents the ratio between useful heating or cooling and the energy required (ratio of heat energy produced to input electrical energy. For example, if you had a heat pump that used 1kWh of electricity to produce 4kWh of usable heat for a home, it would have a COP of 4.

SCOP - Seasonal Coefficient of Performance.

The SCOP gives an indication of the anticipated energy efficiency of a heat pump over a year using standard data across Europe i.e. the average COP (definition above) during a heating season. The temperatures are the flow temperatures of the hot water round your heating system. We have selected 35 and 55 degree Celsius as these are typical for heat pumps with underfloor heating and radiators respectively. Our SCOP figures are those calculated based on the methodology used by MCS. Generally the higher the number, the more efficient the heat pump is.

EHPA or CH quality label

A quality label number for heat pumps based on a common set of requirements. Further details can be found here. The United Kingdom are one of the participating countries (established in the UK by BEAMA and the UK heat pump association).

Heat output A2/W35 (kW)

The useful heat output delivered by the heat pump under the A2/W35 test condition where:

  • W (water) = inlet water temperature [°C] or heater outlet water temperature [°C].
  • A (air) = air inlet temperature [°C].

Noise level inside (dB)

Indoor sound power level according to EN12102 according to manufacturer's specifications.

Noise level external (dB)

Outdoor Sound power level according to EN12102 according to manufacturer's specifications.

Refrigerant

The refrigerant fluid used to transfer heat in a heat pump, which absorbs heat at low temperature and low pressure and releases heat at higher temperature and pressure, usually with changes in the fluid's state.

Smart grid ready

Indicates if the heat pump systems feature control technology that enables the individual heat pump to be integrated into a smart grid.

Inverter technology

Indicates if the heat pump has an inverter-driven variable speed compressor which allows the heat pump to operating between and within its full range by analysing the temperature and conditions inside the home and adjusting the output to maximise efficiency and conform. Heat pumps without this technology are no able to control their energy output (rather it cycles between on and off).

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