Turning Server Heat into Home Hot Water: The Rise of Domestic Datacentres

Heata, a Surrey-based sustainable-cloud provider, installs compact server units onto vented, unpressurised hot-water cylinders (identified by blue insulation). Engineers cut a hole in the insulation, attach the server container with thermal paste, and complete the retrofit in “a couple of hours.” The unit draws grid power, but Heata covers the electricity cost; the homeowner only pays for the required fibre broadband. While processing commercial workloads, the server’s waste heat is transferred into the water tank, providing up to 80 % of the heat needed for domestic hot water. The system is unsuitable for homes with combi boilers, though Heata is developing a version for unvented cylinders.

Domestic datacentres reduce home heating costs by £180 annually The Guardian

Thermify, based in Wales, is testing “HeatHub” units that house roughly 500 Raspberry-Pi-size computers in mineral oil. The oil heats as the computers work and circulates through a heat exchanger to warm water for radiators. Units range from microwave-sized for flats to washing-machine-sized for larger houses. Thermify proposes a £90 per-month lease covering installation, leasing and repairs under a ten-year contract, projecting a 14 % reduction in heating bills for gas-boiler homes and 34 % for heat-pump homes over 15 years.

The Guardian

London homeowner Giles Gibson said his four-bedroom house’s hot-water bill fell by £10-£15 each month after installing a Heata unit, saving £120-£180 annually. He described the setup as “obvious” and a “no-brainer.” Heata’s units are operating in 100 homes, with a waiting list of about 3,000 prospective customers and plans for “hundreds more” installations next year.

Domestic datacentres reduce home heating costs by £180 annually

Thermify’s trial in Essex involves two households using HeatHub units. The firm plans to expand the product line to suit various property sizes, though uptake will depend on compatibility and consumer willingness to lease.

Domestic datacentres reduce home heating costs by £180 annually

Charlie Beharrell, commercial director of Heata, explained that the home provides a convenient location for a server with power and fibre connections, allowing waste heat to be captured efficiently. He noted the primary heating system works “a lot less hard” when the server supplies most of the hot-water heat, with the gas boiler used only during peak demand such as a bath.

The Guardian

Giles Gibson said the system “just makes sense” to repurpose computer heat that would otherwise be wasted, emphasizing the immediate financial benefit of reduced hot-water costs.

The Guardian

Travis Theune, chief executive of Thermify, highlighted the intention to produce units sized for different properties and stressed that the technology offers an alternative route to lower heating expenses while mitigating the environmental impact of large-scale datacentres.

Domestic datacentres reduce home heating costs by £180 annually

Heata is developing a version for unvented cylinders, expanding eligible homes. Thermify aims to launch a broader range of HeatHub sizes and scale production as property owners seek alternatives to traditional gas-boiler heating. Both companies anticipate increased installations as domestic energy costs rise and concerns over datacentre waste heat grow.

The Guardian