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If you’re replacing an old hot water cylinder or planning a new heating system, you’ve probably come across heat batteries. They sound modern and efficient, but are they actually better?
The honest answer is it depends on how you want your home to use energy. For a growing number of UK households, especially those moving away from gas or oil, a heat battery can be a smarter choice.
A heat battery stores energy as heat, rather than storing hot water itself.
A great example is the Sunamp Thermino heat battery. Instead of keeping a tank full of hot water, it uses a special material that stores heat and releases it when needed. In practice, it heats up using electricity, stores that energy, and delivers hot water instantly when you turn on a tap or shower.
Sunamp heat batteries contain a phase change material (PCM) which changes state from solid to liquid when charged. Thanks to this, the units are compact – up to four times smaller than equivalent sized hot water cylinders – and, as they don’t store water, there’s significantly reduced risk of catastrophic failure.
A hot water cylinder is the more traditional setup most homes are familiar with. It stores a tank of hot water that is heated by a boiler, immersion heater, or sometimes a heat pump. Once that tank is empty, you have to wait for it to heat up again.
Modern unvented cylinders can deliver good water pressure, but the basic principle is still the same. You are storing hot water and gradually losing heat over time.
This is one of the biggest differences. A hot water cylinder is always losing heat, even when you are not using it. That energy loss might seem small, but it does add up over the course of a year.
A Sunamp heat battery is far better insulated, and only releases heat when you need it. That makes it more efficient, particularly if you’re heating it using a cheaper off-peak tariff overnight, or if you’re charging it using excess solar generation.
Running costs are where Sunamp heat batteries can really pull ahead. If you’re heating a cylinder using standard daytime electricity, it can be expensive. A heat battery is designed to work with off-peak tariffs, solar panels, heat pumps, and home battery storage. That means you can heat your water when electricity is cheapest and use it later.
Done properly, this can make a noticeable difference to your energy bills.
With a cylinder, you are limited by how much hot water is stored. Once it’s gone, it’s gone until the system reheats.
A Sunamp heat battery works differently. It delivers hot water on demand and, if sized correctly, can provide more than enough hot water for the whole household.
Sunamp heat batteries are much more compact than traditional hot water cylinders. Sunamp Thermino heat batteries can fit into spaces where a cylinder would struggle, and doesn’t require things like loft tanks or additional pipework. This makes it a good option for smaller homes, flats, or anyone wanting to free up space.
If you’re moving towards an all-electric home, adding solar panels, installing battery storage or a heat pump, a Sunamp heat battery fits neatly into that system. It allows you to store cheap or free electricity as hot water, and use it when you need it.
A traditional cylinder can still work, but it isn’t designed with that level of flexibility in mind.
Heat batteries are typically more expensive upfront than a standard hot water cylinder. That said, they are cheaper to run over time, especially if you are making the most of off-peak electricity or renewable energy. It becomes more of a long-term investment than the cheapest option on day one.
If you’re keeping a gas boiler and want the simplest, lowest cost option, a hot water cylinder will do the job. If you’re moving towards a more modern, electric setup and want to reduce your running costs, a Sunamp heat battery is the best choice. It’s more energy efficient, more flexible, and better suited to how energy is changing in the UK.
A Sunamp heat battery isn’t just a different type of hot water system; it’s part of a smarter way of using energy in your home.
If you combine a Sunamp with the right time-of-use tariff and, ideally, solar PV or battery storage, it gives you far more control over when and how you use energy. This is where the real savings come from.
If you’re thinking about the bigger picture, a Sunamp heat battery is a very worthwhile upgrade.
