Home servers cut hot water bills by recycling computer heat
Two UK companies are installing small computer servers in homes to provide heat for hot water and radiators, reducing energy bills by recycling waste
Giles Gibson's hot water is now heated by a compact computer server attached to his cylinder, not by gas. His monthly hot water bill for his four-bedroom London house has fallen by between £10 and £15 since the system was installed last year.
With domestic energy bills rising and environmental concerns about large datacentres growing, several projects aim to harness waste computer heat at home. Gibson's system is supplied by Surrey-based company heata, which runs a sustainable cloud computing business.
How home server heating works
Heata sends processing jobs from its clients to servers installed in domestic hot water cylinders. The company's commercial director, Charlie Beharrell, says the goal is to provide about 80% of the heat needed for a home's hot water. The device has the combined power of about eight laptops.
The system only works in homes with vented, unpressurised water cylinders, typically identifiable by blue insulation. Engineers cut a hole in the insulation and glue the server container to the cylinder with thermal paste. Installation takes a couple of hours and is free for the homeowner.
Heata pays for the server's electricity, while the homeowner covers the necessary fibre broadband connection. The company says millions of UK homes have suitable cylinders, and the units can also work with heat pumps. Systems for homes with combi boilers are not available, though a version for unpressurised cylinders is in development.
Market growth and alternatives
Heata currently has units in 100 homes, with a waiting list of 3,000 people. The company expects to install hundreds more next year. In a separate project in Essex, two households are testing a different concept from Welsh company thermify.
Thermify's HeatHub unit is freezer-sized and contains almost 500 matchbox-sized Raspberry Pi computers. The heat they generate warms a surrounding mineral oil, which then heats water for radiators via a heat exchanger. Chief executive Travis Theune says the system could one day replace domestic boilers.
The company plans a range of units for different home sizes. It claims the device will reduce bill costs by 14% compared to a gas boiler and by 34% compared to a heat pump over a 15-year period, with savings coming from not paying for boiler or heat pump installation.
| Company | Unit Type | Target Home Size | Monthly Cost (Estimate) | Claimed Bill Reduction vs. Gas Boiler |
|---|---|---|---|---|
| thermify | HeatHub (Freezer-sized) | 3-4 bed house | £90 | 14% over 15 years |
| thermify | Smaller unit | Flat | Less than £90 | Not specified |
Theune says the £90 monthly cost for an average-sized home includes installation, unit leasing, and repairs under a minimum 10-year contract. Larger homes would pay more. Gibson, the heata user, calls having a unit "a no-brainer." He says the system provides another little extra that helps his finances.
