Siriusly exciting.

Introducing the efficient new 50-250kW Sirius three range.

Find out more about the Sirius three range
Sirius 3
Output Dry weight Dimensions (WxDxH) Flue connection size ErP
50kW 60kg 600x681x848mm 80/125 A
70kW 70kg 600x681x848mm 80/125 A
90kW 104kg 600x681x1127mm 110/160 (100/150) N/A
110kW 109kg 600x681x1127mm 110/160 (100/150) N/A
130kW 126kg  600x681x1128mm
110/160 (100/150)
150kW 132kg  600x681x1128mm
110/160 (100/150)
200kW 212kg  600x1412x1238mm
150 N/A 
250kW  232kg  600x1412x1238mm
150 N/A 
Up to 1MW N/A


  • Features & Benefits
  • Specifications
  • Dimensions
  • Literature
  • Case studies
  • BIM
  • CAD
  • Enquiry
  • Energy Labelling
  • Outputs of 50kW, 70 kW, 90 kW, 110kW, 130kW, 150kW, 200kW and 250kW, making it suitable for a wide range of commercial applications
  • Wide 9:1 modulation ratio reducing constant on/off cycling to improve efficiency and boiler longevity
  • A gross seasonal efficiency of up to 97.5% reduces energy consumption
  • Supplied with the latest Siemens controls with state of the art PCB, offering improved control options
  • The QA75 Twist Knob Controller has a simple descriptive display and easy to use advanced programming functions
  • Programmable to work with solar thermal, biomass and buffer tanks, for a sustainable, energy efficient solution across the complete range
  • Suitable for LPG conversion; LPG conversion kits are available for off-grid applications
  • Lightweight stainless steel heat exchanger for reliable and energy efficient heat transfer
  • Integrated Low Loss Headers and Plate Heat Exchangers (available as options) are easier to install and offer a professional finish and reduced footprint
  • A very compact design, with casters on the bottom of larger output boilers. Boilers will pass through 700mm doors and are easier to position when space is at a premium
  • 1" flow and return connections (50-70kW) avoids major pipework modification
  • An integrated Cascade function allows up to 16 boilers to be managed by the Siemens controller
  • 0-10 volt connection provides a quick and simple interface with BMS
  • Weather compensation functionality reduces operation costs
  • A low NOx of under 24.6mg/kW minimises impact on the environment
  • ErP compliant, reducing carbon emissions and improving efficiencies in support of government targets
  • Certified for the ETL*, part of the Enhanced Capital Allowance (ECA) tax scheme for businesses
  • Five year parts and labour warranty** for complete peace of mind

*Most outputs. ** Terms and conditions apply. Click here for details.

View product specification

When clicked this will open the product specification in PDF format.


Dimensions and clearance measurements for all models of the Sirius three FS 50kW - 250kW are featured in the tables below.

If you can't find the information you are looking for, you may find it within the product literature.

If you would like to speak to your local Area Sales Manager, please complete the online form within the enquiry tab.


Sirius three FS 50  70  90  110  130  150  200  250 
A Width  600 600 600  600  600 600 600 600
B Height 848 848  1127  1127  1128 1128 1166 1166
C Depth 681 681  681  681  681 681 1412 1412



Sirius three FS 50  70  90  110  130*  150*  200*  250* 
1 Front 1000 1000  1000  1000  1000 1000 1000 1000
2 L Hand 500 500 500  500  500 500 500 500
3 Top 250 250  250  250  400 400 400 400
4 Back 320 320  500  500  500 500 500 500
5 R Hand 500 500 500  500  500 500 500 500

*Back clearance increases to 800 when installed with a low-loss header kit, plate heat exchange kit, or cascade kit

Find out more about the Sirius three FS 50kW - 250kW by reading the case studies below.

Download CAD files for this product using the links below. To access CAD files you will need the correct software installed to allow you to open .dwg files such as AutoCAD

Interested in this product for your premises? Speak to your Technical Sales Manager about this or any of our products.

Can't find the product label or fiche you require below? Try our online calculation tool which allows you to create and download one for a completed system or package installation.