While the Airflow iCON 30 is undeniably a powerful extractor fan, marketing it as a "100mm" fan is incredibly misleading for anyone looking to do a simple like-for-like replacement. Here is what you need to know before buying: The 100mm only applies to the ducting: The spigot at the back connects to a standard 4-inch (100mm) flexible pipe without an issue. The actual motor housing is massive: Because it is a high-power fan, the internal body that houses the motor is much bulkier and wider than a standard flat-backed axial fan. The Joist Problem: If your existing 100mm ceiling hole was cut flush next to a wooden joist (which is very common in UK homes), this fan physically will not fit. You need significant extra internal clearance around the hole to accommodate the oversized body. It is a premium, heavy-duty fan, but the manufacturer needs to be much more transparent that this is not a universal 100mm swap. If your current fan sits right next to a joist, save yourself the wasted time and return postage fees, and look for a standard profile fan instead.
