Start with a route that takes moist air outdoors. Then check the fan is suitable for its intended mounting position, duct run and bathroom location.
Trace the route from the grille to the outlet
A fan on an outside wall may have a shorter route than one in the ceiling. Identify where the duct actually ends and record bends or changes in diameter. A loft or ceiling void is not an outdoor outlet.
Ask about a concealed or cold route
Tell the installer if the duct passes through a cold loft or is difficult to access. Ask how they will manage condensation, support the duct and keep it serviceable. Check whether the fan is approved for wall or ceiling mounting.
Check the electrical location before buying
A registered electrician can confirm the bathroom zone, appropriate rating and means of isolation. Give them the model instructions and a photo of the proposed location before cutting an opening.
Frequently asked questions
Can the fan discharge into the loft?
Plan a duct to outdoors. Ask the installer to check the outlet location and how condensation in the duct will be managed.
For the full checklist, see the bathroom extractor fan buying guide.
Compare the 100 mm run-on timer fan and 150 mm humidity-sensor fan in our bathroom extractor fan range. Check the product specification with your installer before ordering.