Today, more and more UK homeowners are embracing sustainability in a concerted effort to reduce their carbon footprint as well as their energy bills in the midst of an ongoing cost of living crisis.

What’s more:

Ageing gas boilers are being phased out under the UK’s commitment to reach Net Zero by 2050.

So, it should come as no surprise that innovative, environmentally friendly hot water systems like the Sunamp heat battery are gaining in popularity.

But with so many options currently available on the market, you’re probably wondering:

What is a Sunamp heat battery exactly?

And even more crucially:

Are Sunamp heat batteries any good?

To answer these important questions and help you choose the right Sunamp Thermino battery for your specific heating and ventilation needs, at Plumbing Superstore we decided to put together the ultimate Sunamp battery buyer’s guide.

Here’s what we’re going to cover.

Table of contents:

How does a Sunamp heat battery work?

A Sunamp heat battery, such as the Thermino™ range, works as a space-saving, thermal storage solution for hot water in residential and commercial settings. These modern-day heat batteries utilise high-performance phase change material (PCM) to efficiently deliver hot water on demand.


The key to the functionality of Sunamp heat batteries lies in their use of Plentigrade P58 technology, a highly innovative PCM that undergoes a melting and freezing process, similar to the gel in a pocket handwarmer.

Sunamp energy density diagram.Explanation of how Sunamp energy batteries work.

Here’s how it works in a nutshell:

During this phase change, thermal energy is absorbed and released, enabling the storage and retrieval of heat energy as needed. When the material freezes, it releases a significant amount of energy in the form of heat at a constant temperature, ensuring reliable and consistent hot water delivery.

It gets better:

Sunamp heat batteries are designed with ease of use and environmental sustainability in mind. They are easy to install and require no mandatory annual maintenance, which further adds to their appeal for property developers and homeowners looking for hassle-free solutions.

Lastly, the absence of toxic or hazardous materials in Plentigrade P58 eliminates end-of-life disposal concerns, making Sunamp heat batteries a safe and environmentally friendly choice.

But the million-dollar question everyone wants to know is:

Is Sunamp energy efficient?

You bet!

Here’s the deal:

One of the standout features of a Sunamp heat battery is its remarkable energy storage capacity. The unique formula of Plentigrade P58 allows these batteries to store up to four times more energy than water, despite their significantly smaller size.

This is huge!

As a result, Thermino heat batteries can be up to four times smaller than equivalent hot water cylinders, offering space-saving benefits and allowing for easy installation even in compact living spaces.

Sunamp diagram.Breakdown of Sunamp's key components.

Key takeaway:

Whether in new construction projects or as retrofit solutions, Sunamp heat batteries offer a reliable, energy-efficient and environmentally sustainable alternative for hot water storage and delivery.

But how does Sunamp compare to hot water cylinders?

Let’s find out!

Sunamp vs cylinder

Sunamp thermal batteries offer several advantages over traditional hot water cylinders, making them an appealing choice for both homeowners and installers.

Here’s the scoop:

Firstly, the compact size of Sunamp Thermino batteries allows for installation in spaces where conventional hot water cylinders can’t fit. As we mentioned earlier, their innovative use of PCM allows them to store energy more efficiently than water. So, these systems are up to four times smaller than equivalent cylinders.

This versatility makes them ideal for various settings, from busy family homes with limited storage to social housing projects where space constraints pose challenges.

Secondly, Sunamp Thermino batteries have around a whopping 50% lower heat loss compared to standard cylinders thanks to their superior insulation. This not only reduces carbon emissions but also results in lower energy costs for homeowners.

Thirdly, Sunamp batteries are compatible with various energy sources, including grid electricity, heat pumps and solar PV. This flexibility allows homeowners to adapt their hot water systems to changes in their home’s energy mix over time, making Sunamp an extremely versatile and convenient solution.

What is the difference between Sunamp and ZEB?

Sunamp ThermiElectric E Batteries

Sunamp and Tepeo’s ZEB (Zero Emissions Boiler) represent two distinct approaches to modern thermal battery technology for domestic use. Both Sunamp and ZEB incorporate smart technology to optimise charging times, whether from the grid or solar PV.

But that’s more or less where the similarities end.

Here’s why:

As we’ve already discussed in detail, Sunamp uses a compact design and a heat exchanger submerged in a PCM to efficiently provide hot water. It offers flexibility to accommodate different household needs while requiring minimal space, which makes it a versatile option for most properties.

In contrast, Tepeo’s ZEB is an electric boiler that works with existing radiators to heat your home, as it holds around 40kWh of energy for heating. While it can also supply hot water, its limited storage capacity may pose challenges in larger homes or during peak heating demands, particularly in winter months.

So, Tepeo’s ZEB is better suited for smaller properties with lower heating demands.

What size Sunamp heat battery do I need?

In terms of size, most Sunamp Thermino heat batteries are available in four different options – 70, 150, 210, and 300 litres, corresponding to the capacity of the hot water cylinders they replace. Their compact and modular design offers the advantage of versatility, ensuring they can cater to the needs of any household.


You don’t need a Sunamp heat battery review or buyer’s guide to tell you that the ideal Sunamp size for you will vary depending on the size of your household and your hot water demands.

With that in mind, here are our recommendations.

Sunamp Model Equivalent Hot Water Capacity Equivalent Energy Storage Recommended Property Size
Thermino 7070l3kW/h1 bed
Thermino 150150l6kW/h1-2 bed
Thermino 210210l9kW/h3 bed
Thermino 300300l12kW/h4+ bed

Sunamp heat battery cost

Sunamp Thermino range of heat batteries.

The cost of Sunamp heat batteries can vary depending on several factors such as the specific model, size, installation requirements and any additional features or accessories.

The good news is:

Here are Plumbing Superstore, we have a highly affordable Sunamp price list.

But don’t just take our word for it – have a look for yourself.

Sunamp Thermino Batteries Heat

Thermino i is an alternative to indirect cylinders, compatible with boilers, and equipped with an internal electric heating element on standby, offering increased flexibility.

ModelPrice (inc. VAT)
Thermino 70l Heat Battery£1,832.16
Thermino 150l Heat Battery£2,115.48
Thermino 210l Heat Battery£2,717.96
Thermino 300l Heat Battery£2,940.58

Sunamp Thermino ePV Batteries Solar PV

Thermino ePV offers an alternative to direct cylinders, delivering hot water more efficiently through solar PV. It provides the flexibility of grid electricity when required.

ModelPrice (inc. VAT)
Thermino 70 - EPV Heat Battery£1,831.56
Thermino 150 - EPV Heat Battery£2,098.66
Thermino 210 - EPV Heat Battery£2,473.61
Thermino 300 - EPV Heat Battery£3,204.40

Sunamp Thermino Electric E Batteries

Thermino e provides a sleek alternative to direct hot water cylinders, featuring the capability to schedule charging periods for optimal utilisation of off-peak or variable tariffs.

ModelPrice (inc. VAT)
Thermino 70E Heat Battery£1,584.17
Thermino 150E Heat Battery£2,027.66
Thermino 210E Heat Battery£2,406.22
Thermino 300E Heat Battery£2,957.96

Sunamp Thermino hp-SG Heat Battery

Thermino hp combines top-tier heat generation with superior heat storage, enabling the installation of heat pumps in homes where space constraints make it impractical to accommodate an indirect hot water cylinder.

ModelPrice (inc. VAT)
Thermino 150 hp-SG Heat Battery£2,356.03
Thermino 210 hp-SG Heat Battery£2,789.08
Thermino 300 hp-SG Heat Battery£3,255.77

Sunamp Thermino iPV Heat Battery

Thermino iPV efficiently delivers hot water from both solar PV and a boiler, serving as an alternative to indirect cylinders. It also offers the flexibility of grid electricity backup when needed.

ModelPrice (inc. VAT)
Thermino 70 iPV Heat Battery£1,831.56
Thermino 150 iPV Heat Battery£2,362.87
Thermino 210 iPV Heat Battery£2785.36
Thermino 300 iPV Heat Battery£3,187.97

Sunamp Thermino xPlus Heat Battery

A perfect alternative to indirect hot water cylinders, Thermino xPlus operates alongside boilers and heat pumps utilising the compatible Optimino key. Additionally, it can be integrated with solar PV seamlessly by swapping out the Optimino key.

Sunamp Thermino ePlus Heat Battery

Thermino ePlus serves as a smart alternative to direct hot water cylinders, equipped with features to optimise off-peak/variable electricity tariffs and generate cost savings. What’s more, it’s compatible with solar PV thanks to the Optimino PV key, ensuring future-proofing.

Sunamp heat battery installation

Sunamp heat batteries can be installed by a certified plumber or electrician following the provided instruction manual, which contains additional product details. To locate approved Sunamp installers in your area, refer to Sunamp’s official website.

This is important:

According to the Sunamp product warranty, installation of a thermal battery requires competence. While no specific training courses are mandated, individuals must possess the necessary qualifications, knowledge, training and experience to understand basic plumbing and electrical work, similar to installing an unvented hot water cylinder.


The specific installation process will vary somewhat depending on which type of Thermino heat battery you opt for.

To get a general idea of the steps involved, check out this video from Sunamp.

Why you should seriously consider a Sunamp water heater

With its innovative and highly efficient thermal technology, a Sunamp heat battery offers plenty of benefits for residential hot water needs.

The thing is:

Its compact design, fuelled by high-performance phase change material, ensures fast and reliable hot water delivery while occupying significantly less space than traditional cylinders. This space-saving feature is particularly advantageous for homes with limited storage capacity or those looking for a sleek, modern solution.

What’s more:

Sunamp’s compatibility with various energy sources, including heat pumps and solar PV, allows homeowners to reduce their carbon footprint and energy costs.

Bottom line:

With easy installation, minimal maintenance requirements and a deserved reputation for reliability – Sunamp problems are few and far between – a Sunamp heat battery provides a convenient and environmentally friendly choice for households aiming to optimise energy efficiency and comfort.

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