24 hour timer on bathroom fan

[newbuyer17]

Ideally it would be good to have the fan run off the shower, not the light. This would be possible if you wired it to the shower isolator switch and switch it off after use, which I don't.

But... Is there any way of sensing current draw from the isolating switch and using that as a trigger? In other words sensing when the shower is on.

 

[bernardgreen]

A flow switch in the cold feed to an electric shower can be used to trigger the fan timer.

 

[JohnW2]

Ideally it would be good to have the fan run off the shower, not the light. This would be possible if you wired it to the shower isolator switch and switch it off after use, which I don't.

Even if you did, thatt would be a bit of a hassle, because, strictly speaking, you would probably have to find a way to include a fuse in both the live and switched live feeds from the shower isolator.

But... Is there any way of sensing current draw from the isolating switch and using that as a trigger? In other words sensing when the shower is on.

Technically possible, but one would need to experiment. A 'clip on' current sensor (such as used for 'energy monitors') might be adequate to produce a 'trigger' input for the fan (equivalent to the usual 'switched live' connection. However, as bernard has said, a flow sensor is another approach - or maybe even a PIR or proximity sensor to detect the presence of someone in the shower cubicle.

Kind Regards, John

 

[EFLImpudence]

Fitted a more powerful inline fan to our ensuite,

Do you perhaps have a more fundamental problem which has caused you to think that that may be a solution?

 

[newbuyer17]

Fitted a more powerful inline fan to our ensuite,

Do you perhaps have a more fundamental problem which has caused you to think that that may be a solution?

Not really, just multiple showers in a solid brick walled house. Seems common sense to me to get rid of the moisture at source.

Anyway, was just about to order and realised I have an old timer from a warmup underfloor heating system. Am I correct in assuming I can just use that instead of a immersion heater timer?

 

[Taylortwocities]

For air to EXTRACT efficiently you must also allow at least an equivalent volume of air INTO the space. Otherwise the fan will never be efficient.

Also, the length and type of ducting will have an effect.

I have an old timer from a warmup underfloor heating system

Yes you could use that, those timers are good for a lot more current than the fan will need.

 

[ban-all-sheds]

A flow switch in the cold feed to an electric shower can be used to trigger the fan timer.

Or if it's a mixer shower, a thermal switch on the hot water feed. Even better, that can be retrofitted without needing to cut the pipe.

 

[newbuyer17]

OK, if anyone is still interest, I ended up with a different solution.

http://www.amazon.co.uk/gp/product/B0060HGASI

Took the permanent L/N from the fan permanents, and fed the live back from the unit to the switched live on the fan.
The sensor itself is low voltage so safe to have in zone 1, though whether it is technically compliant is another matter.

The main downside is the sensor has a wide angle of coverage (80 degrees) so in order to stop false alarms I had to position right in the corner of the shower enclosure next to the walls, and also cover half of it over. Using a semi-circle cut out of silver duck tape looks fairly neat.

So far so good, fan comes on when you get into the shower enclosure, and stays on x minutes after you get out via the fan's delay timer. Going in during the night for a number 1/2 doesn't set it off.

If you really do want the fan on, you just need to wave your arm into the enclosure.