Heat-pump design warning signs

Core idea

A credible heat-pump proposal connects room heat loss, design outdoor temperature, flow temperature, emitter output, hot-water demand and equipment capacity. It also addresses sound, siting, electrical supply, hydraulics and controls. A selection based only on floor area or the old boiler rating misses the evidence needed for comfort and performance.

What to recognise

• Look for a room-by-room heat-loss calculation and stated design conditions.
• Check emitter outputs at the proposed water temperatures.
• Confirm the unit capacity at the relevant outdoor and flow temperatures.
• Identify hydraulic volume, minimum flow and defrost provisions.
• Record how domestic hot water and any backup heat will operate.

Apply it

Use these points as a design-review checklist. If the proposal quotes only a model number and an annual COP, ask for the missing loads, temperatures and emitter assessment. One unusually cold design hour and average seasonal operation are different checks and need different evidence.

Keep the boundary clear

This awareness note does not qualify someone to design or commission a heat-pump system. Use the current specialist standard, manufacturer data and competent designer. Planning, acoustic, electrical, refrigerant and Building Regulations requirements remain separate parts of the job.