• Householders are getting free hot water from Heata, a company that installs rented servers in homes
• Heata pays for any additional electricity used, ensuring homeowners win and businesses have their data stored safely

What happens to waste heat from servers? In a server room or data center, the heat is removed through industrial cooling systems and exhausted. But what if it could be reused? What if that heat could be used to keep domestic heating bills down?

Heata is one of several companies across the UK and Europe delivering solutions to server space and heating costs. Domestic waste-heat use appears to be a growing industry, and offers homeowners the chance to cut bills significantly while giving businesses low-cost server space.

The idea is simple: install a server in the home, rent the server space to businesses, and donate the heat generated by compute processes to the home, reducing their energy bills in the process.

How servers heat homes

If you’ve worked in a server room, you know how hot things can get, particularly if there is a problem with the extraction system. This is the starting point for these so-called “data furnaces” where the heat from an active compute unit is used to heat water. Heata say that the waste heat from a single data center could provide hot water for around 30,000 homes, which puts it into context.

Their model is simple: a compute model is attached to a hot water cylinder, heating the water and reducing the requirement for gas heating. Homes need fast broadband to provide fast data routing to the compute module, and Heata pays for additional electricity used by the mini server. It aims to provide around 80% of heat for the heating system, reducing domestic gas bills considerably.

Like Heata, Wales-based Thermify is looking for trial customers. Their system is a little different, relying on a HeatHub, within which a cluster of Raspberry Pi Compute Modules are generating data solutions and heat.

Compatible boilers

While the having a server or compute unit in a remote part of your property to assist in heating the water – essentially using the same electricity twice – might seem an attractive option, it does not come without shortcomings. For example, there is the issue of compatibility.

With the Heata example, only vented hot water cylinders can be used. Unvented, pressurised cylinders are not compatible. Other providers of similar data-to-heat services can provide the heated water in other ways – for example, Thermify uses its HeatHub to replace a home’s boiler.

With no new homes permitted to have gas boilers installed from 2027 onward, an alternative to hot water is needed, and companies turning data into heat could be the best solution.