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Glow-worm Ultimate3 Combi

Glow-worm Ultimate3 Combi

The Glow-worm Ultimate3 Combi is a modern gas condensing combination boiler that offers fantastic efficiency and performance.

If you’ve been searching for a budget boiler that’s easy-to-use and a breeze to maintain, the Ultimate3 Combi should be right up your street. It’s A-rated for efficiency, suitable for a range of properties and features some impressive components. This offering from Glow-worm also comes with a good warranty and can be used with a variety of optional controls to make the boiler more efficient and user-friendly.

How Much Does this Boiler Cost?

Glow-worm’s Ultimate3 Combi comes in an output of 30kW or 35kW, so the cost will mainly depend on which model you need. The smaller model is around £695 and the larger option has a £770 price tag. Then there’s the fitting cost to consider, which can vary enormously. If you want to save on the boiler and installation costs, you’ll need to get a range of quotes from different installers.

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

The Ultimate3 Combi is a combination boiler, so it will provide on-demand heating and hot water without the need for a separate storage cylinder or loft tanks. As combi boilers don’t require additional cylinders or tanks, they are often suited to flats and small houses but this boiler is more ideal for medium to large-sized homes. It’s important to know that combi boilers cannot send plenty of hot water to multiple taps and showers that are being used simultaneously, so they are rarely recommended for homes with more than one bathroom.

It’s always a good idea to ask a Gas Safe registered engineer what type and size (output) of boiler is best for your home and needs to enable you to make sensible buying decisions.

Is it a High Efficiency Boiler?

This boiler is A-rated for efficiency, so it is highly efficient and a good option if you’re looking to replace an old boiler so that you can save on your energy bills. No matter which model you choose, the boiler comes complete with a Grundfos modulating pump to help keep your energy use low. You can even improve efficiency when you use the Ultimate3 Combi with a Glow-worm optional control, such as a wired or wireless room thermostat or the MiGo personal heating assistant.

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

It has similar controls to most other Glow-worm combi boilers including adjustable heating and hot water temperature buttons. Like we said above, the boiler is compatible with a range of optional controls to enhance performance and user experience. The MiGo app-based control is pretty neat because it learns your unique energy requirements and enables you to manage your heating and hot water using a smartphone. As for features, the boiler has a bright LCD display for clear visibility and an automotive-grade aluminium heat exchanger for superior performance. Additionally, it has a modulating Grundfos pump for better efficiency and an inbuilt filling loop for hassle-free maintenance.

How long is the Warranty on this Boiler?

The Ultimate3 Combi comes with a 5-year parts and labour warranty as standard with the option to extend if the installation is carried out by a Glow-worm Club Energy installer.

Glow-worm Ultimate3 Combi Boiler Prices and Sizes


ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
Ultimate3 Combi 30CombiH – 740 mm
W – 418 mm
D – 300 mm
12.4 l/min30 kWA 90% and above£695
Ultimate3 Combi 35CombiH – 740 mm
W – 418 mm
D – 300 mm
14.4 l/min35 kWA 90% and above£770

Summary of Important Information

  • Priced between £695 and £770
  • Heating output of 30kW or 35kW
  • Hot water flow rates of 12.4 or 14.4 litres per minute
  • 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

Even though Glow-worm has built the Ultimate3 Combi with most UK homes in mind, you’ll still need to ask a Gas Safe registered engineer to assess your property and needs before spending any cash on it. You also need to consider its pros and cons, which you can find below.


  • Suited to medium to large-sized homes
  • No need for separate cylinder or loft tanks
  • Easy to use and service
  • Grundfos pump – reduces energy use and fuel bills
  • Automotive-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%
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