Electrifying heat in urban apartments

A space-saving heat battery and heat pump combination replaces a gas combi boiler in a UK city home to deliver the electrification of heat and a lower carbon footprint.

Reducing fossil fuel use with a heat battery and heat pump combination
Delivering low-carbon hot water from a flexible time-of-use electricity tariff
Saving space with no need for a hot water cylinder

The challenge

The owners of a three-bedroom apartment in Edinburgh, Scotland, wanted to replace their gas boiler with a new, environmentally friendly heating system.

However, they didn’t have enough space inside their flat for the large hot water cylinder that often accompanies a heat pump.

The solution

The UK government’s Electrification of Heat (EoH) Demonstration Project was looking to better understand the feasibility of large-scale rollout of heat pumps into existing homes and was trialling different types of heat pumps, along with some additional technologies, in 750 homes across the UK.

This gave the homeowners the opportunity to remove their gas boiler and install an air-source heat pump combined with a compact Sunamp heat battery for their hot water.

As a result, a Sunamp UniQ 9 heat battery, the equivalent of today’s Thermino 210, was installed in the utility room and a heat pump outside the ground-floor property. It only took two and half days to fit by a team of accredited installers involving plumbers and electricians.

The benefits

The Sunamp heat battery can charge using electricity at the cheapest time of the day. This makes the most of the flexible time-of-use tariff that the owners already had. The heat battery is set to charge overnight using cheaper rates between 2-5am, avoiding the peak time of 4-7pm when the rates are higher.

The heat battery around four times smaller than the equivalent hot water cylinder since it stores thermal energy in energy-dense phase change material instead of water.

All concerns about lacking space vanished as the Sunamp heat battery fitted easily next to their washing machine, neatly and quietly making plenty of hot water for when they need it. At mains pressure too.

The heat pump is also quiet. It stands outside the owners’ bedroom window and they cannot hear it. They’ve even checked with their neighbours who said that any noise from the heat pump’s operation is not an issue.

As they no longer have a combi gas boiler and use off-peak electricity, the owners calculated that their carbon footprint has reduced since installing the heat battery and heat pump combination.

In this home, the Sunamp heat battery is equivalent to a 212-litre tank.

We're thrilled with it! We couldn't be happier with the heat battery. The consistency of temperature and water pressure are far superior to the combi boiler performance."

Homeowners, Michael and Joan.


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