MCS Standards

MCS Technical Working Groups develop the MCS standards, which are predominantly based on international and European standards already in existence.

Heat Pumps

An Air Source Heat Pump (ASHP) is a system which absorbs heat from the outside air and turns this into useful heat energy for space heating and domestic hot water. This can be in the form of air to air (providing heated air for space heating) or air to water (providing heated water for space heating and/or domestic hot water).

An Exhaust Air Source Heat Pump (EAHP) is a system which absorbs heat from the waste air (or exhaust air) leaving a building. Heat is extracted from the Exhaust air and is upgraded into useful heat energy for space heating and domestic hot water. As heat pumps do not create heat, EAHPs primarily rely on other heat inputs to a building such as heat gains from internal equipment /occupants or from an auxiliary form of heat energy into the building. Therefore they are applicable for very low heat loss applications. A very small proportion of heat is provided by the outside air itself similar to an air source heat pump. This type of heat pump requires a certain air exchange rate to maintain its output power.

A Gas Absorption Heat Pump (GAHP) is a system which use gas to drive the heat transfer process using the partial pressures of two different chemicals at low pressure (rather than an electric driven
compressor operating at high pressure which is used in most heat pumps). It requires a gas or LPG supply. In all other senses these systems operate like any other heat pump, absorbing heat from the outside air, ground or water source and turning this into useful heat energy for space heating and domestic hot water. This can be in the form of air to air (providing heated air for space heating) or air to water (providing heated water for space heating and/or domestic hot water).

A Ground Source Heat Pump (GSHP) is a unit which absorbs heat either directly or indirectly from the ground by extracting & re-injecting water from an aquifer (direct) or by using a ground heat exchanger (in-direct) which is usually a closed loop of pipework buried within the ground (vertically or horizontally) conveying a water/antifreeze mixture as the heat transfer medium. It upgrades this low temperature heat into useful higher temperature heat energy for space heating and domestic hot water. This can be in the form of ground/water to air (providing heated air for space heating) or ground/air to water (providing heated water for space heating and / or domestic hot water).

Water Source Heat Pumps (WSHP) extract the heat from open water courses such as rivers, lakes and canals and can also extract water from sea water.

A Solar Assisted Heat Pump (SAHP) is a system which absorbs atmospheric heat (e.g via an external absorber) and turns this into useful heat energy for domestic hot water. An external absorber acts as an evaporator and utilises the heat in the atmosphere as well as direct solar radiation. Generally the absorber will be placed externally however in some cases may be placed internally. At present MCS only covers SAHPs which provide domestic hot water however it is possible this may change to include space heating in the future.

Below are the standards required to be met to be able to install Heat Pump systems under the MCS scheme. Approved guidance and reference materials to be used with the standards can also be found below. Please note that heat pump installations commissioned on or after 26/03/2016 must comply with new MCS product requirements aligning the scheme with the Energy related Products Directive.  For further information click here.

Technology Specific Scheme Requirements
Heat Pump Systems 
MIS 3005 Heat Pump Standard 4.3 06.05.2015
MIS 3005 Heat Pump Standard 5.0 28.04.2017
FAQs FAQs for MCS 007 V5.0 & MIS 3005 V4.3 1.0

70kWth Application Guidance* 1.0 15.05.2014
MGD 002 Guidance for MIS 3005 1.2 20.02.2012

Installer standards that have been withdrawn are available for reference here.


Heat Pump Reference Materials

Heat loss calculations for heat pumps

Installer companies may use any heat pump calculation software that complies with EN12831. Alternatively, installer companies may use the MCS heat pump calculator (please see below).

Supplementary spreadsheets and documents
General design
MCS 031 MCS Heat Pump System Performance Estimate template 2.0 22/05/2018
Calculator MCS Heat Pump Calculator

Please submit any feedback to with a subject heading of ‘MCS heat pump calculator feedback’

Maintenance is currently being undertaken to amend the MCS Heat Pump Calculator

1.8 18/04/2018
Guidance MCS Heat Pump Calculator User Guide 1.1 11/04/2016
Guidance U-Values from Domestic Heating Design Guide v1.0 1.0
Guidance Domestic hot water cylinder selection guide 1.0
Heat emitter design
MCS 021 Heat emitter guide 2.1 01.05.2015
Guidance Table of heat emitter outputs
Hydraulics design
Guidance MCS Hydraulics Design – Pressure Drop Charts v1_0 1.0 23/03/2012
Guidance GSHP Hydraulics Design Guide v1.0 1.0 23/03/2012
Worksheet GSHP Hydraulics Worksheet v1.0 1.0 23/03/2012
Ground loop design
Guidance Ground loop sizing tables 1.0 02/09/2011
Heat metering design
Guidance MCS Domestic RHI Metering Guidance Document 1.1 01.05.2015

Grid connection forms

The following forms should be submitted to the relevant Distribution Network Operator (DNO) before connecting a heat pump to the elecricity grid. Please contact the product supplier for all product data required to complete the forms and the DNO for further information on the forms.

Document Download here
Form A – Word Click here
Form A – PDF Click here
Form B – Word Click here
Form B – PDF Click here
Form C- Word Click here
Form C – PDF Click here

Archived Support Materials

For a list of MCS heat loss support materials (including presentations from training roadshows organised in 2011 and old heat loss calculators) please click here.


*The MCS Standards Management Group (SMG) has prepared a guidance document (found above) to assist installers and the wider industry in understanding the intent of how the thresholds, set within each MCS Installation Standard for the heat technologies, shall be practically applied to design, installation and commissioning work under the MCS scheme.

This document has been prepared by the MCS SMG, taking into account the views of the industry to ensure that systems can be adequately designed and installed under the scheme, whilst reinforcing with installation companies the need to ensure they have the relevant competencies to undertake the tasks associated with these systems.
An MCS certified Installation Company should ensure they follow this guidance, and MCS reserves the right to amend the guidance as necessary through periodic review without prior notice.
The 70kWth threshold was noted by the Scheme as a threshold which aligns with the existing competency criteria set out by the Scheme, and other industries such as oil and gas.