Bathroom extractor with relay

[jchapman9]

I have an inline fan in the loft operated by a movement sensor overlooking the shower. I found humidity sensors gave up after a while. The movement sensor has the timer function built into it. As this setup wasn't doing a very good job of extracting, I installed a Manrose Showerlite directly over the shower, a more powerful fan, and a Y piece linking to the original extractor vent.

Problem is the Showerlite needs the fan on when the lights are on to dissipate heat. As there is plenty of light in the bathroom, the lights aren't needed all the time. Nor do I really want the fan to stay on for 20 mins if someone just pops into the bathroom to look at a spot or something.

What I would like to do is insert a relay between fan, lights and sensor such that by default the fan is operated by the motion sensor using the NC connection, but if the lights are turned on the relay switches to the NO connection and the fan is switched on. When the lights go off, the fan stops unless the sensor has been triggered. At the moment, the fan is driven by the sensor which has a 2 pole FCU isolating it. I imagine I would need a separate FCU isolating the fan itself and maybe another for the relay. Ideally, a mains relay with mains coil would be easiest.

Is there a proprietary solution for this or any suggestions re choice of relay etc?

Thanks.

 

[EFLImpudence]

Not a popular topic?

Problem is the Showerlite needs the fan on when the lights are on to dissipate heat.

Is this a requirement in the manufacturer's instructions?

I have not seen it in the links I have found.
It's just a normal light and it has a chimney.

What I would like to do is insert a relay between fan, lights and sensor such that by default the fan is operated by the motion sensor using the NC connection, but if the lights are turned on the relay switches to the NO connection and the fan is switched on. When the lights go off, the fan stops unless the sensor has been triggered. At the moment, the fan is driven by the sensor which has a 2 pole FCU isolating it. I imagine I would need a separate FCU isolating the fan itself and maybe another for the relay. Ideally, a mains relay with mains coil would be easiest.

If it is necessary to have the fan on to cool the light then all you need is the relay to power the fan when the light is on.
It would not be necessary to have the motion sensor connected to the relay - or vice-versa.

Follow the manufacturer's instructions as far as FCUs are concerned.
They are not electrically necessary.

Is there a proprietary solution for this or any suggestions re choice of relay etc?

Any relay for 240V will be suitable.
Maplins have them - ref. N24AW or N09AW and others.
http://www.maplin.co.uk/30a-spdt-power-relay-37495
http://www.maplin.co.uk/10a-dpdt-miniature-relays-37518

Also, I am not sure about the Y piece.
Where does the other leg go?

 

[jchapman9]

Thanks for the reply. Yes, the docs with the Showerlite say the light needs the fan operating at the same time. The ducting Y piece goes to the previous (poorly sited) ceiling vent - too far from the shower to do any good - as well as the Showerlite and out through the fan.

I'll pop in to Maplins at the weekend.