how the heata unit works - housing overview

We help landlords improve the energy efficiency of their housing and offer free hot water to their tenants

Benefits

EPC improvement

By 2026 new tenancies must have an Energy Performance Certificate (EPC) rating of C or better, and all tenancies by 2028. EPCs are also required when properties are built or sold.

The heata unit is expected to improve the EPC rating by 4-8 points. Heata is undertaking the Standard Assessment Procedure (SAP) to trial the units and calculate the improved energy performance. The Building Research Establishment (BRE) will then add the heata unit to its database of products used to calculate EPCs.

Free hot water

For landlords mandated to meet EPC targets, the heata unit is a cost effective alternative to expensive and disruptive building works.

Installation takes around 2 hours and once installed, the waste heat from compute heats the household’s hot water – delivering up to 4.25kWh of hot water per day. At current prices it could save them up to £340 a year ^[1] depending on the primary heating source that the heata unit is off-setting.

Meet the heata unit

A powerful compute server that attaches to domestic hot water cylinders, the heat generated by the processing is transferred into the cylinder using a patented thermal transfer mechanism.

How the heata unit works. New way to 3D render

Installation overview

Our patented thermal bridge is fitted to vented domestic hot water cylinders and provides the attachment point for our powerful server.

We've tested the installation process with British Gas engineers and checked that it doesn't invalidate cylinder warrantees with one of the UK's largest cylinder manufacturers.

To find out if your cylinder is suitable for a heata unit, download our summary brochure which includes the cylinder checklist and installation overview.

Download

Diagram - How the heata unit works with your boiler

Get in touch

The heata unit can be retro-fitted to the majority of domestic hot water cylinders and is a great fit for social housing organisations who want to decarbonise their housing stock and help tenants with their electricity costs. If you'd like to find out more, we'd love to hear from you.

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FAQ

A 'host' is the household with the heata unit installed on their hot water cylinder.

How much hot water does a heata unit provide per day?

The heata unit can deliver up to 4.25kWh of hot water per day.

What kind of carbon saving does the heata unit offer?

Each heata unit saves approximately 750kg of carbon dioxide per year, vs a typical data centre + household heating.^[2]

How much can a host save per year?

Based on average household hot water yearly usage (water heated using electricity not gas), the host could save up to £340 / year at an electricity price of 22p / kWh.

Who pays for the electricity and how do you know how much electricity the heata unit uses?

Heata pays for the electricity to run the device, not the host. The electricity used by the unit is metered (the host can see the meter reading on the power supply unit) and the host's utility account is credited for the amount used.

What is the projected EPC improvement?

We estimate that the heata unit will improve the EPC rating by 4-8 points depending on the primary heating system. We are going through the SAP process with BRE in 2023-2024 to confirm the number of points.

Does the heata unit replace the host’s boiler or immersion heater?

No, the heata unit will provide a base load of hot water; approximately 80% of an average household’s hot water requirement. The host’s current hot water heating system stays in place and will provide top-up heat as required / per their central heating controls.

Does installing a heata unit invalidate my cylinder's warranty?

The installation procedure is a larger version of how a standard tank stat is installed. We’ve tested the installation process with a British Gas engineer, and spoken to a leading cylinder manufacturer who confirmed that following the approved installation process won’t invalidate a cylinder's warranty.

Is a plumber needed to install the heata unit?

No, an electrician fits the heata unit to the outside of the hot water cylinder and it doesn’t need to be plumbed in. This simplifies installation, and avoids the ongoing liabilities of problems associated with any plumbing work.

Does adding a heata unit change the energy efficiency rating of the cylinder?

No, whilst the unit is installed it will be always on, giving heat to the cylinder. When decommissioned, a plug / cap of equal or greater thermal resistance will cover the hole.

Does the size of the unit prohibit its installation in tighter spaces / airing cupboards?

Yes, in some cases it won’t be possible to install the unit. It is something we’ll manage carefully as part of the initial pre-installation process.

What happens when something goes wrong with a heata unit?

The host doesn’t lose any hot water as their existing heating will continue to function. The repairs team is notified automatically and they will be in touch to arrange a time to replace the unit. Once initial installation has been completed, repairs and updates are relatively quick as the unit is simply bolted to the mounting plate that is already in place on the cylinder.

How often will an engineer need access for maintenance?

We schedule a yearly maintenance visit, much like a yearly boiler service to maintain your Gas Safety Certificate.

What is the lifespan of the unit?

Like most computer hardware, being outdated / unprofitable to run (perhaps 4 years) tends to happen before failure, a swap to new hardware will take about 30 minutes.

Does the heata unit use the host’s broadband?

Connectivity is flexible, we can use the host's broadband but plan to install dedicated fibre or 4G / 5G connections.

Will the unit interfere with other wireless equipment installed in the house?

The unit has passed EMC testing, which means that it won't affect the host’s electronic equipment, including WiFi.

Does the unit produce any noise, if so what dB?

The heata unit uses variable speed low noise air circulation fans, no louder than 30db (a whisper) at max speed.

Can the host use the processing power of the heata unit?

No, the computer processing is used and paid for by companies who want to process their data more sustainably - it’s a lovely story for them to know that their compute doesn’t require air conditioning and is providing free hot water for a household.

What safety measures are in place to prevent the unit or water from overheating?

There are 4 levels of overheat protection:
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1. All processors throttle their speed (and therefore power output) when they reach their max operating temp.
2. The machine will monitor the case and water temperature on the machine and reduce work accordingly.
3. There will be an auto reset-able thermal switch in the unit, which will temporarily cut the power to the unit if the above measures fail.
4. There will be a non auto reset-able thermal cut out as a back-up to the above device.

3 and 4 are as those found in standard immersion heaters, so as to comply with EN60335-2-73 (National Safety Standards).

Will the water get hot enough to prevent pathogens?

There is no additional risk from the unit, as the primary water heating system is still active. If anything, with better monitoring we'll be able to identify problems that might stop the water getting sufficiently hot to prevent the development of pathogens.

Could a host gain access to the heata unit?

There are chassis intruder alarms, and all peripherals are disabled and physically inaccessible. The storage within the heata unit is LUKS / AES-256 fully encrypted and inaccessible if removed from the heata unit.

How secure is the heata network - can the heata unit see what the household is accessing and viewing online?

Very secure, we’re working with SUSE, leveraging their secure edge platform, providing enterprise grade security in physically exposed public infrastructure. E.g. Mobile base stations. Heata units are on a private subnet, isolated from the host’s network and all network traffic goes out through a VPN (AES-256 encrypted) to the wider internet, so the host’s home network is completely inaccessible to compute workloads and vice-versa.

If the unit is removed what happens to the area without insulation?

A plug / cap of equal or greater thermal resistance will cover the hole, the cylinder's warranty is unaffected.

Still have questions? Get in touch

References

Yearly cost saving is based on hot water heated with electricity at 22p/kWh, or heated with gas at 7.8p/kWh (takes into account a boiler efficiency of 70%[3]), with the heata unit supplying 4.25kWh of hot water per day. A billing accredited submeter is installed along with the heata unit and the household is credited for the amount of energy that the heata unit uses.
CO₂e saving is based on: Typical Data Centre + domestic hot water: 750W/hour (330W compute + 200W cooling[4] + 220W hot water) vs heata: 330W/hour (330W compute, including 220W harnessed from waste heat), at 80% utilisation across the year. Carbon intensity is 0.274kg CO₂e/kWh, this is derived from the blend of heating sources in the homes in the heata network. Base carbon intensity is 0.236 CO₂e/kWh for Electricity and 0.290 CO₂e/kWh for Gas, taking into account an assumed boiler efficiency of 70%[3].
Greenhouse Gas Reporting Conversion Factors 2023.
Ni, Jiacheng & Bai, Xuelian. (2017). A review of air conditioning energy performance in data centers. Renewable and Sustainable Energy Reviews. 67. 10.1016/j.rser.2016.09.050.