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Ceiling Fan Timer

It runs the fan in your bathroom or toilet for a fixed time after you turn it on and has two modes of operation

By John Clarke

Main Features

  • Fan runs for preset time period
  • Connects to standard fan wiring using original switch
  • Adjustable time period from 20 seconds to 22 minutes
  • Immediate timer start or delayed timer start (selected by single on-board jumper link)
  • Up to three times period extension using immediate timer mode
  • Piezo sound indication for switch on and period extension

Unless you can keep your windows open all the time, you really do need ceiling exhaust fans in your toilet and bathroom to clear steam and odours. Good ventilation stops mould growing on the ceilings and walls and minimises water condensation on the walls and windows if you are having a long, hot shower.

This Fan Timer is housed in a plastic box which is installed near the fan, usually in the ceiling. When you build it, you can set the Timer for one of two modes of operation which we have called "immediate" and "delayed" modes.

In the "delayed" mode, you switch the fan in the normal way using the wall switch. The fan then runs for as long as the switch is left on. When you flip the wall switch off, the fan will then run for a preset period before it switches off automatically.

Click for larger image
Fig.1(a) at left shows how the fan is normally connected, which Fig.1(b) shows how the Fan Timer is interposed between mains Active and the fan.

In the "immediate" mode, the fan is also switched on using the wall switch but in this case, the fan will then run for a preset period before it switches off automatically. If you need to run it for a longer time, you flip the switch to its other position to make the fan run for the same preset period. Alternatively, you can extend the fan running time by the same preset period, by flipping the wall switch to its other position before the fan stops. If you do this, the fan timer will acknowledge the time extension by giving a short beep.

In fact, you can do this twice, to run the fan for three times the normal preset period. Switching a third time turns the fan off.

Each mode has its advantages. The "immediate" mode has the advantage that the fan switch does not need to be manually switched off. This mode is ideal for a household with children!

The "delayed" mode is more suited to people who want to run the fan as long as they are in the bathroom or toilet and who always remember to manually switch off the fan when they leave (letting it run for the preset time). Our choice would be to use the "immediate" mode – that way you don’t have to remember to switch off!

The preset running period can be selected from 20 seconds up to 22 minutes. Depending on the room and size of the exhaust fan, a setting of around 5-10 minutes would usually be selected.

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