Guide · Costs
Heat pump hot water cylinder cost
The component most often missing from a suspiciously cheap quote.
A heat pump hot water cylinder costs £900–£2,200 supplied and fitted in the UK in 2026, depending on capacity and whether the airing cupboard needs rebuilding. Heat pump cylinders need a much larger internal coil than boiler cylinders — typically 3 m² or more — so a standard boiler cylinder cannot simply be reused.
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Why the coil size matters
A heat pump delivers water at 50–55°C for hot water, not 70°C+ like a boiler. To transfer heat fast enough at that lower temperature, the cylinder coil needs a much larger surface area. Reusing an old boiler cylinder leads to long reheat times and poor efficiency.
Sizing by household
- 1–2 people, one bathroom: 150–180 litres, £900–£1,300 fitted.
- 3–4 people, one to two bathrooms: 180–210 litres, £1,200–£1,700 fitted.
- 5+ people or two-plus bathrooms: 250–300 litres, £1,600–£2,200 fitted.
What is included in a good quote
- Unvented cylinder with heat pump coil, expansion vessel and safety group.
- Immersion heater for the weekly legionella cycle.
- Secondary return insulation where there is a long draw-off run.
- Building Regulations G3 notification by a qualified installer.
Frequently asked questions
- Can I use my existing cylinder with a heat pump?
- Rarely. Most boiler cylinders have a coil too small for heat pump flow temperatures, which makes hot water slow and inefficient.
- How much does a heat pump cylinder cost?
- £900–£2,200 supplied and fitted, depending on litres and installation complexity.
- Do I need an immersion heater?
- Yes — it runs the periodic high-temperature legionella cycle and provides backup hot water.
- Energy Saving Trust — Heat pump efficiency, running cost and SCOP benchmarks (UK).
- MCS Certified — Installer certification scheme required for grant eligibility.
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