Boosting installation standards for heat pumps

Space heating, Daikin, heat pump
Enhancing the reputation of heat pumps — Stuart Gadsden.

The latest revisions to the MCS Microgeneration Installation Standard for heat pumps are designed to raise design and installation standards and help give end users reassurance that their system will comply with best practice, says Stuart Gadsden of Daikin UK.

It is easy to dismiss a revision of industry standards as yet another example of increasing bureaucracy but sometimes, as in the case of the recent revision to Microgeneration Certification Scheme (MCS)* changes can be a force for good. Mainly affecting domestic properties, this new revision, which came into being earlier this year, is designed to raise installation standards and help give end users reassurance that their installation meets the highest criteria.

If systems are designed and installed correctly, end users will be more satisfied, the reputation of renewables will be enhanced, and the market will grow, which is good for everyone.

All MCS heat-pump installations now have to comply with the updated standard, which emphasises that every heat-pump application should be treated individually. It also ensures installers understand the new requirement that the heat pump should be carefully selected to cover 100% of the heat load at defined outdoor temperature criteria, reducing the risk of an incorrect heat pump being selected. The changes are also designed to ensure that households are fully aware of the type and characteristics of the system they will own for the next 15 or so years.

Complete solution — Daikin’s heat-pump Altherma system delivers space heating and domestic hot water.

To take full advantage of the new standard, those involved in designing, specifying and installing renewable heat-pump systems must fully understand the changes and their implications. The whole text is available from the MCS website along with a series of training aids, which we recommend are read and understood clearly.

The big change in the new standard is that heat loss must now be calculated on a room-by-room basis at the MCS outdoor temperature using a calculation method that complies with BS EN 12831. Design internal air temperatures and ground temperatures are specified. Due to the varying performance at low temperatures, a heat-loss calculation at temperature extremes is also recommended to ensure the heating system can provide sufficient coverage in worst-case winter conditions.

MCS has provided an online room-by-room heat-loss calculator. Other software tools can be used in order to show compliance. Daikin has developed its own room-by-room heat loss calculator for use by its accredited installers.

This should ensure that the process of system designs will become standardised, with higher overall quality being attained. It is worth noting that this full process should only be undertaken once preliminary cost estimates have been agreed with the home owner, as the extra work required can take some time and effort.

Certain aspects of design have become mandatory, including the heat-pump unit being able to deal with 100% of the peak heating load at a specified CIBSE ‘Guide A’ external temperature. Electric back-up heaters can still be incorporated into the system, but can only be used below the specified MCS design temperature. Also, bivalent fossil fuel sources can be used, as long as the controls are fully integrated and the system is explained to the end user.

Careful location of outdoor units will avoid noise problems and inadequate air circulation.

A new heat-emitter guide has been published to help explain the impact of emitter selection and design flow temperature on the estimated heating-system efficiency to the homeowner. System designers should also provide a full explanation of the running-cost estimate, including system pumps, cylinder losses, use of immersion heaters for hot water and so on.

The efficiency of a heat-pump system depends on the ambient temperature and also on the design temperature of the heat-emitter system. The implications of using standard radiators at a high system temperature compared with a more efficient low-temperature emitting system such as underfloor heating should therefore also be explained.

If the system design is to include providing domestic hot water, this must now be calculated to BS EN 6700 or EN 806, taking into account the number and type of washbasins, sinks, baths and showers being used. It must also take into account the size of the hot-water storage cylinder or thermal store, the cylinder heat exchangers and bacteria-management system.

Lastly, the location of the heat pump has to be considered — to account for potential noise issues and anything that might prevent air recirculation, which could hinder the outdoor unit’s performance.

The new installation standard will ensure that future heat-pump installations follow a similar procedure for system design and that home owners are kept fully informed throughout the design and selection process. This can only lead to higher understanding and satisfaction from home owners and even further reduced carbon emissions, as well as an enhanced reputation for the industry as a whole.

Stuart Gadsden is heat-pump specialist with Daikin UK.

* Microgeneration Installation Standard, MIS 3005 v3.1a

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