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Ultimate₃ system boiler

Exclusive system boiler with 5 years warranty*

  • ErP A rated for efficiency - helping to reduce energy bills
  • FREE 5 year warranty with option to extend*
  • £15 reward when registered through Club Energy
  • Available as 25kW model

The Ultimate₃ is Glow-worm’s high performance, ErP A rated boiler range developed for the one off installer market, and exclusively manufactured for City Plumbing Supplies.

The Ultimate₃ sealed system boiler provides a reliable and efficient heating solution for homes with a high hot water demand, and is available as a 25kW model. The high performance model features a Grundfos modulating pump for reduced energy consumption, a manual pressure gauge for easy installation, flexible flue options for easy siting, and a modern, bright, LCD display with a simple-to-use interface.

Designed using an automotive grade aluminium heat exchanger, the Ultimate₃ offers proven reliability and performance whilst being light to install and easy to maintain.

The complete Ultimate₃ range (including combi, system and regular/open vent options) is compatible with the full range of Glow-worm controls including the popular MiGo app based control.

The Ultimate₃ offers installers a £15 reward and comes with a free 5 year warranty when registered through Club Energy; where installers can also benefit from business tools including the Plumbing Toolbox app, Gas Safe Notifications, Benchmark and some great rewards.

*When registered through Club Energy

Features & benefits

  • Sealed system boiler range available in a 25kW output
  • Modern, bright, LCD display with easy-to-use interface
  • High quality, automotive grade, aluminium heat exchanger providing excellent performance
  • High efficiency, A rated boiler for ErP energy labelling to reduce energy bills
  • Modulating Grundfos pump for reduced energy use
  • Manual pressure gauge to make installation easy
  • Uses familiar Glow-worm diagnostics for easy install & servicing
  • Inbuilt filling loop
  • Compatible with full range of Glow-worm controls, flues and accessories
  • Ideal for use with innovative MiGo app based control
  • 5 years parts and labour guarantee with option to extend*
  • Telescopic flue option available
  • ø60/100 and ø80/125 flue options available
  • Wide range of Glow-worm accessories available including spacing frame and pipe cover plate
  • Plume Management kit compatible

*When registered through Club Energy



Ultimate₃ system boiler25kW
Casing dimensions (H x W x D mm)740 x 418 x 300
Weight (lift) (kg)32
CH output minimum/maximum (kW)6.1/25.5
SEDBUK rating 2009 (%)89.3
NOx class (natural gas)5
LPG compatible No
ErP ratingA
Heat exchanger materialAluminium
Burner typePre-mixed
Fully modulatingYes
DHW plate heat exchangerYes
Integrated hydroblocYes
Suitable for sealed systemsYes
Inbuilt filling loopIntegrated
Inbuilt condensate trap/siphonYes
Inbuilt boiler frost protection2 Stage
Zero compartment ventilationYes
Top (from top of boiler mm)300
Side (mm)0*
Bottom (mm)300
Front (mm²)600**
User interface
User displaySuper bright LCD
User adjustable CH temperature controlYes
Water connections (mm)2 x 22/2 x 15
Maximum horizontal Ø60/100 (m)9
Maximum vertical Ø60/100 (m)9
Maximum horizontal Ø80/125 (m)25
Maximum vertical Ø80/125 (m)25
Optional plume management kit Ø60/100Yes
Optional spacing frameYes

*See manual for clearance if side panels are to be removed to assist future service and maintenance

** 5mm if removable panel/door

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 boiler

Exclusive combi boiler with 5 years warranty*

  • Leading combi boiler offering great performance
  • FREE 5 year warranty* with option to extend
  • £15 reward when registered through Club Energy
  • Available in 30kW and 35kW models

Ultimate₃ regular boiler

Exclusive regular boiler with 5 years warranty*

  • ErP A rated for efficiency - to reduce energy bills
  • £15 reward when registered through Club Energy
  • Lightweight boiler with cupboard fit dimensions
  • FREE 5 year warranty with option to extend*