DIY Doctor UK DIY Forums

Hey all

Any ideas why this is happening.

I’m have newish build apartment that I lived in for a few years, then rented out to three different tenants. The latest tenant just left, but all of a sudden, the extractor fan in the bathroom is staying permanently on. It previously operated on the bathroom light switch, and turned itself off after about five minutes after the light switch turned off.

When I turn off the correlating switch on the consumer unit, the fan goes off. But then turns by itself on as soon as I turn the power back on, without the light switch.

I’m a bit confused at to why this happening.

The fan doesn’t have any setting controls.

Any idea of how to fix?

Ps I bought a new fan from Screwfix, but needs a fused spur to operate. Am I correct in thinking fused spurs aren’t allowed in a bathroom?

Any recommendations for an extractor fan that doesn’t need a fused spur?

When I wired up the new fan, the fan failed to turn on.

The old fan had

N
L1
L

The new fan I wired everything the same, but had S/L instead of L1. But the the new fan failed to turn on.

I assume L1 would go into S/L?

I would swap over the 2 lives, looks like the permanent live is in the switch live. Be careful you don’t move the neutral wire.
There should be a triple pole isolation switch outside the bathroom, normally above the door.
Also there should be a timer switch inside the fan to alter the run on time after the light has been switched off, normally from 0 secs to 10 mins approx.

yeh I tried switching the Live with Switch Live but fan failed to turn on completely. Also apartment doesn't have isolator switch - only the switch on consumer unit in the cupboard. I've ordered a like for like fan replacement so hoping that should fix. The current fan doesn't have a timer unfortunately - I'm think possibly its a humidity sensor that may have possibly gone caput?