I have a bathroom fan, but it only runs when the light is on (i.e. no delay). The fan itself is really good, but it should really run on after (I think this might be part of the Building Regulations here in UK).
I don't want to replace the fan, so was wondering if you can just get the timer unit to attach in-line somewhere.
I've checked and the wiring is there for the permanent live as well as switched live, so am kind of hoping it will be simple!
I'm not sure about the UK, but in the US we have in-wall timer units that are often used for this purpose. Like this Maestro timer from Lutron.
You said that "I've checked and the wiring is there for the permanent live as well as switched live," so my assumption is that one switch is connected to both of these.
In this configuration, you will have the hot from the line connecting to the switch, and then the switch connecting to the two hots for the light and fan. Use a wirenut and attach two pig tails to the incoming hot line. Connect one to a switch and the other to a timer and then connect the hot from the light and fan to the switch and timer. If you only have a single-gang box then you will need a combination timer/switch. Alternatively you can remove the box and install a larger electrical box to accommodate both the switch and timer.
You mentioned in your comment that you're having trouble locating a timer. Here's one I found on Amazon.
If you have a permanent live at the fan, you also might look into a fan with a humidity sensor. These come on automatically when they sense humidity above a certain level and then cycle off automatically.
Just go to a plumbing store and ask for a timer for your bathroom exhaust fan. The timers come with wiring instructions and the one I installed came with 3 wires.
I found a couple of options - the Swiftair Timer and the Manrose 1351. I'll go for the Swiftair one as it's only £10. Much cheaper than a new fan or a humidity sensor one.
Thanks for advice all though.
