Baxi Multifit IFOS
The new In Flue Outdoor Sensor

Introducing Baxi's cost effective, easy to install accessory to help you comply with Boiler Plus.

We are delighted to introduce the new Baxi Multifit IFOS in flue outdoor sensor. Compatible with all Baxi combi boilers, IFOS is an easy and cost effective way to comply with the requirements of Boiler Plus, when combined with a time and temperature control.

IFOS can be fitted to any horizontal flue, regardless of the aspect of the wall, because it fits under the air duct and is kept out of direct sunlight. And the cable runs back to the boiler through the flue air duct, so you won't have to drill any walls to route unsightly cables.


  • Sensor housing clips onto the air duct of the horizontal flue terminal, so can be fitted quickly and easily
  • IFOS fits under the air duct, so it is kept out of direct sunlight. This means installation is not restricted to a north-facing wall
  • Free flow of air over the sensor for more accurate temperature sensing
  • Two wire cable runs back to the boiler down the flue air duct, so it is extremely simple to fit, with no drilling, disruption or unsightly cables
  • Very few parts, making it an easy solution compared with many other weather sensors.

Listen to the Baxi IFOS Podcast

Have a listen to our podcast with Paul Stockall, Product Manager and John Dieterman, R&D Team Leader talking to Expert Trades on everything IFOS.

Download the literature here:

Multifit IFOS installation instructions

Multifit IFOS information sheet