Exploring why heat pumps can underperform
27th April 2026
UK: A new technical book explores the engineering, hydraulic and control issues that prevent heat pump systems from delivering expected performance in real buildings and plantrooms.
Why Heat Pumps Fail: The Engineering Mistakes That Kill Performance — And How to Avoid Them, is authored by Craig Moreton, the current controls and heat pump systems lead at Trane UK.
Moreton’s experience ranges across domestic, commercial and industrial heat pump applications. His work focuses on the interaction between heat pump equipment, hydraulic design, controls, commissioning and real-world system behaviour.
Written for HVACR professionals, heat pump designers, consultants, contractors, manufacturers, commissioning engineers and technically minded clients, the 291-page book examines why heat pump systems often underperform once installed.
Rather than blaming the heat pump itself, the book focuses on the wider system conditions around the machine. It argues that many poor outcomes are caused by design and application issues, including excessive flow temperatures, weak hydraulic design, poor emitter matching, incorrect buffer application, poor controls, domestic hot water behaviour, cycling, defrost and commissioning assumptions.
The book challenges what Moreton describes as the “boiler mindset” — where heat pumps are sometimes applied using assumptions developed around high-temperature boiler systems.
It explains why heat pump performance is conditional, why a single COP figure does not represent real operation, and why every system must be considered against its actual load profile, ambient conditions, flow temperature, return temperature, system volume, control strategy, part-load behaviour and defrost requirements.
For HVACR readers, the book also looks at plantroom behaviour, multi-unit staging, heat recovery, hydraulic separation, buffer vessel performance and the way control strategy can either stabilise or destabilise a heat pump system.
Why Heat Pumps Fail is available now on Amazon.
