• Get FREE Quotes today
  • Compare quotes & save money
  • Over 5,000 engineers across the UK
Tell us about your job
Get Free Quotes

Glow-worm Ultimate3 System

The Glow-worm Ultimate3 System is a gas condensing sealed system boiler that is smart compatible and A-rated for efficiency.

If you want to replace your old boiler with a new energy efficient model that is backed by a great warranty, the Glow-worm Ultimate3 System could be the answer. Ideal for homes with high hot water demands, this boiler comes complete with a straightforward interface and a load of impressive features that promise to help reduce your fuel bills. It’s also compatible with a range of optional intelligent accessories including the MiGo app-based control that lets you manage your heating and hot water via a smartphone.

How Much Does this Boiler Cost?

Glow-worm’s Ultimate3 System comes in an output of 25kW and has an average cost of £810. Don’t forget, you’ll need to have the boiler installed by a professional, which is an additional cost that usually starts at around £1,500. To save on boiler and installation costs, we recommend you shop around and compare quotes from local and national installers.

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

The Ultimate3 System by Glow-worm is a system boiler and will require a separate cylinder for storing your hot water. This type of storage cylinder is commonly housed in an airing cupboard. System boilers are best suited to homes with high demands and properties that have more than one bathroom because they can provide a constant supply of hot water, even when multiple taps, showers or baths are running simultaneously. They’re also ideal for dwellings with limited loft space as there is no need for any loft tanks.

As it’s essential that you choose the right type and size of boiler for your property, you should always consult a Gas Safe registered engineer before you fork out for a new boiler. If you pick a boiler that is too big or small for your needs, you’ll see an increase to your energy bills or your system won’t be capable of producing enough heating and hot water for your home.

Is it a High Efficiency Boiler?

Yes. This boiler is ErP A-rated and has an efficiency of 94%, so it should help to cut the cost of your annual energy bills. It has some high-efficiency features, such as a modulating Grundfos pump that can adapt the boiler’s output to meet your heating and hot water requirements. Also, the Ultimate3 System can be used with Glow-worm’s range of intelligent controls that are designed to improve boiler efficiency.

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

When it comes to controls, the boiler has all the usual buttons and switches together with controls that let you adjust the temperature of your heating and hot water. The Ultimate3 System is compatible with optional controls too, but you will need to pay more to get your hands on these. Glow-worm’s most popular control option is the MiGo personal heating assistant that cleverly learns your energy requirements and enables you to control both the heating and hot water from your smartphone or tablet. This boiler also has a clear LCD display, the high-efficiency Grundfos pump and a high-grade aluminium heat exchanger for superior performance.

Glow-worm Ultimate3 System Boiler Prices and Sizes

ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
Ultimate3 System 25SystemH – 740 mm
W – 418 mm
D – 300 mm
N/A25 kWA 90% and above£810

How long is the Warranty on this Boiler?

If you purchase the Ultimate3 System, you’ll receive a 5-year parts and labour warranty but your Gas Safe registered installer must register the installation on the Club Energy loyalty programme.

Summary of Important Information

  • Expect to pay around £810
  • Heating output of 25kW
  • Dimensions of 740mm (H) x 418mm (W) x 300 (D)
  • Uses gas as its fuel source
  • A-rated for efficiency
  • Smart compatible
  • 5-year warranty as standard

Pros and Cons

Below, you can find all the pros and cons of the Glow-worm Ultimate3 System. If you think it could be a good option for your home, remember to get some professional advice from a qualified Gas Safe engineer before parting with any money.


  • Suited to small to medium-sized homes
  • Easy to use and service
  • 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
  • 5-year warranty


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

Get quotes to supply a new Glow Worm boiler now