This short guidance note gives a comprehensive overview of the considerations that must be factored in when designing and specifying an air-to-water heat pump system.

The paper is aimed at designers at initial stages of design, and covers design choices that have a substantial impact on energy performance. It includes some simple aspects that are easy to understand, and some more complex aspects that are often missed, even by experienced services engineers. Most can be applied to any project irrespective of building energy standards.

Topics addressed include flow temperatures, overall system design, distribution losses, heat pump and emitter sizing, system controls, and input into PHPP.

The paper has been reviewed and endorsed by CIBSE.

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