Sunamp Heat Batteries — Compact, Low-Carbon Hot Water Storage

Sunamp Heat Batteries is a Scottish engineering company and recipient of the UK's first ever King's Award for Enterprise in thermal storage innovation. Their Thermino heat battery range replaces traditional hot water cylinders with a compact, phase-change alternative that stores up to four times more energy per litre — delivering instant mains-pressure hot water in a unit small enough to fit under a kitchen counter.

At the core of every Thermino is Plentigrade P58, Sunamp's patented phase-change material developed with the University of Edinburgh. As the material melts and re-solidifies, it stores and releases precise, controlled bursts of thermal energy — with ultra-low standby losses and a tested lifespan of over 50 years and 40,000 charge cycles, RAL certified with no measurable degradation.

Why choose Thermino over a conventional unvented cylinder or heat pump water heater?

• Up to 4× smaller — fits under stairs, in kitchen cupboards, in spaces where a cylinder simply cannot
• G3 exempt — less than 15 litres of water held internally, so no unvented certification is required
• Zero mandatory maintenance on the unit — no annual servicing, no Legionella risk from stored water
• Works with every energy source — grid, solar PV, heat pump, and boiler via Optimino key accessories
• Qualifies for the Boiler Upgrade Scheme as ancillary equipment when installed with a heat pump
• 50+ year lifespan — the PCM doesn't degrade, making it a one-time infrastructure investment

We stock the Thermino ePlus (direct electric, for grid or solar PV), the Thermino xPlus (indirect, for heat pump and boiler systems), and the full suite of Optimino Keys — including PV keys for solar integration, boiler keys, and heat pump keys for compatibility with leading brands. We also stock the Sunamp Installation Kit, containing all the ancillary components your installer needs to commission the unit correctly — including expansion vessel, pressure relief valve, and push-fit connectors. Order everything together for a smooth, one-delivery installation.

Over 30,000 Sunamp units are installed across UK homes, new build developments, and retrofit projects. Whether you're a homeowner upgrading from a combi boiler, an installer specifying for a heat pump project, or a developer future-proofing a new build against the Future Homes Standard, Thermino is the compact, compliant, and proven choice.

Available at AIZO Quality Heating with next-day despatch options. Need help specifying the right model or key? Call us on 020 4577 3096 or email service@qualityheating.co.uk.