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Glow-worm Energy System Boiler

The Glow-worm Energy System can provide a constant supply of hot water without the need for a cold water tank in the loft.

Manufactured in the UK, the Glow-worm Energy System is a compact gas condensing boiler that can be kept virtually anywhere in a small, medium or large home. Not only can it meet high hot water demands but the boiler can help you to reduce your carbon footprint and annual energy bills. The boiler has also been awarded the Quiet Mark accreditation, making it ideal if you want to house it in the kitchen or in any of your other high-traffic rooms.

How Much Does this Boiler Cost?

As five models make up the Energy System series including 12kW, 15kW, 18kW, 25kW and 30kW, prices range between £710 and £840. Another important cost to consider is the installation, which can vary depending on your location and how much work is required to fit the boiler. Because boiler and installation quotes tend to differ quite a bit, you may be able to save money when you take the time to shop around.

How will I know if this Boiler is Suitable for My Home?

The Glow-worm Energy System is a type of system boiler, which heats water and then stores the heated water in a hot water cylinder to ensure a constant supply of hot water. These storage cylinders are commonly found in airing cupboards. Unlike heat only boilers, system boilers do not require any tanks in the loft, so the Energy System is suitable for properties without any loft space. It’s also a practical option for homes that have more than one bathroom because it can deliver hot water to multiple taps and showers at the same time.

Before you purchase this boiler (or any other boiler), you’ll need to ask a Gas Safe registered engineer to assess your heating and hot water requirements so that they can help you to select the correct boiler type and output for your property.

Is it a High Efficiency Boiler?

Glow-worm’s Energy System is ErP Rated A for efficiency and Energy Saving Trust endorsed, meaning this boiler meets strict energy efficiency criteria. If you have an old boiler at home and choose to replace it with this one, you should expect to see a drop in your fuel bills. To enable the boiler to save more energy and money, it can be used with a range of optional controls including traditional plug-in timers, the Climapro2 RF wireless programmable thermostat or the intelligent MiGo app-based control.

Does this Boiler have a Good Range of Controls and Features?

Yes. This compact and extremely quiet system boiler has a clear LCD display and various user-controls, so you can adjust heating and hot water temperatures with ease. Optional controls are also available, such as the popular MiGo personal heating assistant that learns your energy needs and allows you to control your system from a smartphone. The boiler even has a high-quality aluminium heat exchanger for optimum performance, along with a modulating Grundfos pump that can adapt to your heating and hot water demands to ensure you save as much energy as possible.

How long is the Warranty on this Boiler?

The Energy System comes with a free 7-year parts and labour warranty as standard. This can be extended but only when you hire a Glow-worm Club Energy installer to carry out the installation.

Glow-worm Energy System Boiler Prices and Sizes


ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
Energy System 12SystemH – 700 mm
W – 390 mm
D – 280 mm
N/A12 kWA 90% and above£710
Energy System 15SystemH – 700 mm
W – 390 mm
D – 280 mm
N/A15 kWA 90% and above£740
Energy System 18SystemH – 700 mm
W – 390 mm
D – 280 mm
N/A18 kWA 90% and above£770
Energy System 25SystemH – 700 mm
W – 390 mm
D – 280 mm
N/A25 kWA 90% and above£810
Energy System 30SystemH – 700 mm
W – 390 mm
D – 280 mm
N/A30 kWA 90% and above£840

Summary of Important Information

  • Priced between £710 and £840
  • Heating output of 12kW, 15kW, 18kW, 25kW or 30kW
  • Dimensions of 700mm (H) x 390mm (W) x 280 (D)
  • Uses gas as its fuel source
  • A-rated for efficiency
  • Smart compatible
  • 7-year warranty as standard

Pros and Cons

It’s hard to find fault with this boiler, however, Glow-worm boilers have been rated average by owners and engineers who took part in a Which? boiler brand survey. That’s not to say that this boiler won’t meet your expectations, though. Perhaps you should look at customer reviews that specifically mention the Energy System before making a final decision. In the meantime, you can check out all of its pros and cons.


  • Fits in a kitchen cupboard
  • Suited to small, medium and large-sized homes
  • Easy to use and service
  • Quiet Mark approved
  • Grundfos pump – reduces energy use and fuel bills
  • High-grade aluminium heat exchanger – reliable performance
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Compatible with a range of intelligent controls – improves efficiency and performance
  • Compatible with the MiGo app-based control – maximises efficiency, learns your energy needs and allows you to manage your heating and hot water from anywhere
  • 7-year warranty


  • Glow-worm boilers have an overall Which? score of 54%
  • Requires separate cylinder
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