Public BETA

Help us make the new Sunamp website even better.

Please share your feedback using the form below.

Replacing gas boilers in UK high-rise tower blocks

Compact heat battery and heat pump integrated system design enables the removal of gas combi boilers from 364 space-constrained homes while increasing resident safety and reducing CO2-emissions.

Saving space, lowering running costs and reducing maintenance needs
Cutting carbon dioxide emissions by an estimated 70% per year
In a UK first, replacing the gas supply in occupied, high-rise buildings with minimum disruption to the residents

The challenge


When faced with the dilemma of how to completely remove the gas supply and replace old combi boilers without decanting residents from 364 apartments in seven tower blocks in northern England, housing association Gentoo Group turned to energy services supplier ENGIE for advice.

To complicate matters, any new system would have to be easy to use and fit into the limited space available in each home. This ruled out installing traditional hot-water systems and the associated pipework. Unvented cylinders were impractical to fit because of the nature of the building.

Some of the homes benefiting from Sunamp’s heat batteries. Part of Gentoo Group’s ‘Core 364’ gas replacement programme in Sunderland.

The solution


A space-saving Sunamp UniQ heat battery in one of Gentoo Group’s homes. It is more compact than traditional hot water cylinders.

The answer was an integrated system combining Sunamp’s super compact UniQ heat batteries and Kensa Contracting’s small and quiet Shoebox ground source heat pumps, controlled by a smart, easy-to-use interface from Switchee.

This fully integrated system is fed communally but managed locally, providing residents with greater individual levels of control and comfort, and lower running costs.

The benefits


As a result, building safety improved as there is no longer any potential risk of a gas-related explosion, and the risk of carbon monoxide poisoning and disease infection from legionella is eliminated.

Maintenance costs are considerably reduced as there is no longer any need for annual gas safety tests and certification, nor cylinder safety checks.

Carbon emissions will be reduced by an estimated 420 tonnes, or nearly 70% per year.

The Sunamp / Kensa partnership solution has enabled gas supplies to be removed for the first time from occupied high-rise buildings in the UK, with minimum disruption. The same system can equally be applied elsewhere and bring the same advantages to lower density housing.

The technical details


  • Carbon savings: approximately 420t/year (-70%)
  • Heating capacity: 308 x 3kW + 56 x 6kW (1.26MW)
  • Storage capacity: 364 x 9kWh (3.28MWh)
  • Heating source: individual heat pumps (Kensa Shoebox) and heat batteries (Sunamp UniQ) connected to an open-loop ground-source system
  • Heat pump supply temperature: space heating up to 55°C and heat battery charging up to 65°C

Want to find out more?


Learn more about our offering for the public housing sector

Contact our team for a bespoke assessment of your project