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Ultimate₃ regular (open vent) boiler

High efficiency regular boiler from Glow-worm

  • High performance, ErP A rated regular boiler
  • £15 reward when registered through Club Energy
  • Lightweight boiler with cupboard fit dimensions
  • FREE 5 year warranty* with option to extend

High performance

The Ultimate₃ regular boiler provides outstanding heating performance in a 25kW model, and is best suited to homes with high hot water demands, where a hot water storage cylinder and a cold water tank are already installed.

Being both lightweight and very compact, the Ultimate₃ regular boiler can easily be installed within a kitchen cupboard if required.

The boiler features a modern, bright, LCD display with an easy-to-use interface, and is also compatible with Glow-worm’s popular MiGo app based control (sold separately) – meaning you can control your heating and hot water from anywhere at anytime by simply using your mobile phone or tablet.

The Ultimate₃ also comes prepared with a 5 year parts and labour guarantee, when your Gas Safe registered installer registers the installation, on the Glow-worm Club Energy installer loyalty programme.

*When registered through Club Energy

Features & benefits

  • Superior performance regular (open vent) boiler available in a 25kW model
  • Modern, bright, LCD display with easy-to-use interface
  • Kitchen cupboard fit dimensions
  • High quality automotive grade aluminium heat exchanger providing excellent performance
  • Highly efficient, A rated boiler for ErP energy labelling to reduce energy bills
  • Ideal for use with innovative MiGo app based control - when used in conjunction with the appropriate system pack
  • 5 years parts and labour guarantee*
  • Wide range of Glow-worm flues and accessories available

*with option to extend when registered through Club Energy



Ultimate₃, Regular Boiler25kW
Boiler dimensions (H x W x D mm)600 x 375 x 280
Ø60/100 flue length horizontal (m)9
Ø60/100 flue length vertical (m)9
SEDBUK 2009 annual efficiency (%)89.3
ErP ratingA

Related Products

Related Products

Climapro₂ RF Control

Climapro₂ RF

  • Two channel wireless programmable room thermostat
  • Backlit display provides advanced user control and functionality
  • Capable of room and weather compensation*
  • Simple to use handheld unit

Introducing MiGo

The personal heating assistant

  • Wi-Fi thermostat and easy-to-use app
  • Manage heating and hot water from anywhere
  • Reduces energy consumption, saves money
  • Internet weather compensation
  • eBUS communication

Climastat room thermostat

  • Easy to use
  • Extra low voltage
  • Simple & discreet 2 wire connection
  • Polarity not important

Climapro₁ control

Available wireless and wired

  • Annual service reminder function
  • Automatic update for summer and winter
  • Simple and discreet
  • Weather compensation ability (when used with optional outdoor sensor)



Alternative products

Alternative products

Ultimate₃ combi boilers

High efficiency combi boiler from Glow-worm

  • Leading combi boiler offering outstanding performance
  • ErP A rated for efficiency – helping you to reduce your energy bills
  • FREE 5 year parts and labour warranty*
  • Extended warranty options available
  • Our 30kW and 35kW models suit homes of all sizes

Ultimate₃ system boiler

High efficiency sealed system boiler from Glow-worm

  • Highly reliable system boiler offering outstanding performance
  • ErP A rated for efficiency – helping you to save money on your energy bills
  • FREE 5 year parts and labour warranty*
  • Extended warranty options available*
  • Available in a 25kW model