bathroom fan - how to delay start

[gregd72002]

Hi,

I've installed a fan in my bathroom that starts when bathroom lights are switched on and stops 5 minutes after the lights are switched off. Work great!

Though, I do not need the fan to be on when I brush my teethes or wash my hands. But I need it only when the shower (combi boiler) is on. What are the options?

I was thinking of getting some kind of 5 min delay start so the fan does not start until after 5 minutes of the lights being constantly on.

Are there any other options?

Thanks,

 

[Taylortwocities]

Some fans have a delay start feature.
SOME VentAxia fans and you can get a module for the Icon fans
http://www.alertelectrical.com/prodvar/3965/airflow-icon-delay-start-timer
but the max delay is 2 minutes and that's not long enough even for teeth brushing.

You would have to rip out the fan you have just installed and put in a new one.

Or you'd need to get a bunch of relays and 555 timer from Maplin and get with the soldering iron.

 

[ericmark]

There are regulations about bathroom fans and one has to first work out if you need the fan or if it's an optional extra.

Windows make a huge difference as if it opens you don't NEED a fan but if there is one that does not open then you can't have the fan solely controlled by the lights. You need an alternative way to switch it on.

Often a purely mechanical time switch is used. Just a push button which once pressed holds on for so many seconds. It does not NEED to be controlled by the lights.

Where the fan is needed then there is also a minimum run on time I think around 15 minutes which does seem a long time. Provision of the replacement air is also in building regulations as a depression within the house could cause flue gases to be drawn into the house.

The fan I fitted for my father had a humidity control so it auto turns on when the shower is used. But no good where loo smells are concerned.

I would think going to loo and brushing teeth are both short times.

Using a PIR is another option. This does not need the lights switching on.

Since fans do fail and when they do one still wants to be able to use the lights normally an isolator is fitted so the fan can be turned off. There are specials with have three sets of contacts designed for when lights work the fan. So in 99% of cases simply switching the fan off on the isolator would allow you to brush ones teeth.

Where the fan wants less than the protective device used for lights for example 3A not 6A then using a double pole light switch and a FCU is one option. This also lends its self to adding a push button to run fan without lights.

Does that give you enough ideas?

 

[gregd72002]

ericmark,

regulations - i got window in my bathroom...

PIR - same problem - when using loo fan will be on

buttons, etc - you tend to forget about them.. and definitely you do not want to jump off your shower just to switch on the fan

I guess I will simply get some time delay relay and fit it in

 

[rjm2k]

You could just add a pull switch and turn it on manually when you want it working rather than running off the light switch.

Or, if it already has an isolator, just remember to isolate it when you don't want it running.

 

[Taylortwocities]

Well you could get something like this:
http://www.maplin.co.uk/universal-timer-kit-3315

then you'll need a 12v DC power supply to power it

then the output relaly on the board is not rated for 230v AC so you'll need another relay

Then you'll need to find a way to trigger it as the input does not accept 230V (another relay?)

Then you'll need to work out how to apply the logic as this timer will operate when it is triggered and switches off after a timer period (like a timer fan). You need it to work in the opposite way - ie operate 5 minutes after the trigger has occurred,.another relay?

That's gonna be a bunch of work.

 

[gregd72002]

taylortwocities, i think I will go around theses lines.. all the stuff you mention and on 230VAC is done by this...
http://uk.rs-online.com/web/p/time-delay-relays/3306654/

so sounds simple enough though a bit costly..

 

[ericmark]

I will assume opening window so fan an optional extra.

There are hundreds of time switches but most cost silly money. The cheap way is to build your own simply a delay off with relay changing it to delay on.

When working in a factory we considered if we needed more than 3 timers then better to fit a full PLC this was because the timers were so expensive. This Timer will do what you want but you would need a box to mount it in. They are not designed for domestic use.

 

[gregd72002]

ericmac, yes the window is opening...


lol, I like the option for 10days delay on the device

 

[ban-all-sheds]

But I need it only when the shower (combi boiler) is on. What are the options?

Put a flow switch in the supply to the mixer.

 

[JohnW2]

Though, I do not need the fan to be on when I brush my teethes or wash my hands.

Is it really that much of a problem for the fan to come on when you brush your teeth or wash your hands? Are you perhaps concerned about noise in the middle of the night? If not, then, as you can see, any solution is going to cause you a bit of effort/hassle/expense, so maybe better to just accept the situation 'as is'?

Kind Regards, John

 

[gregd72002]

But I need it only when the shower (combi boiler) is on. What are the options?

Put a flow switch in the supply to the mixer.

This is something I never heard of! interesting... as it cost only around 10GBP...

Thanks a lot ban-all-sheds!!! Might invest the 10quid to try it out

 

[RF Lighting]

Well you could get something like this:
http://www.maplin.co.uk/universal-timer-kit-3315

then you'll need a 12v DC power supply to power it

then the output relaly on the board is not rated for 230v AC so you'll need another relay

Then you'll need to find a way to trigger it as the input does not accept 230V (another relay?)

Then you'll need to work out how to apply the logic as this timer will operate when it is triggered and switches off after a timer period (like a timer fan). You need it to work in the opposite way - ie operate 5 minutes after the trigger has occurred,.another relay?

That's gonna be a bunch of work.

Or just use one of these:

http://www.ebay.co.uk/itm/Chint-NTE...ial_Automation_Control_ET&hash=item589260cfdd

Delays up to 8 mins. If that's not long enough, put two in series.

Personally I'd have the fan running all the time, but if you want a delay, that's up to you.

 

[gregd72002]

Thanks guys!

Another question - do i need a vent hole in my bathroom door?

I just installed new bathroom door which are pretty well aligned (no much of a space around the door for air in and out) which are on the opposite wall to the fan and window wall.

If yes, how big should be the vent hole in the door?

 

[GaryMo]

But I need it only when the shower (combi boiler) is on.

What about smells? Don't you want them extracted too?
Have a dump, flush the bog, turn the shower on, turn the shower off!