Inline fan switched from two locations

[S P]

Good evening all,

Has anyone ever installed a fan like this before?
The issue I don't know the best way to overcome is that if I wire each bathrooms SL to the fan it will back feed and turn the lights on for both bathrooms.

The best I've come up with is 2x contactors - one SL to each input - then both outputs to SL on fan isolator. L+N from both junctions straight to fan isolator.

Is there a better way of doing this?

I thought it would be a good idea as it is serving two small back to back en-suites, accessible loft space above for the fan. They are much more powerful than the standard wall/ceiling units. Plan was one duct out - Y joint at fan to each room.

The contractors will cost around £55 so unless someone knows a better solution it makes more sense to install two fans.. They cost £65 each

Thank you

 

[Taylortwocities]

Use double pole switches. One pole for the light in each room and the other pole as the fan on/off.
Cointactors, relays and the like not required!

Simples!

 

[jackhammerJIM]

The times i have installed fans in this configuration i used a 2 gang switch at each location keeping light and fan separate .

 

[S P]

Thanks Taylor, Jack

Both rooms have no natural light.
Do you think this needs to be followed? Quote From IET forum:

You do not have to use a timer fan at all.

The only legal requirement in the Building Regs. is "There shall be adequate means of ventilation provided for people in the building."

Anything noted in the Approved Document for Part F is merely a suggestion. As the Approved Documents themselves point out, "There is no obligation to adopt any particular solution contained within an Approved Document if you prefer to meet the relevant requirement in some other way."

However, even if one were to try and follow the guidelines in the Approved Document for Part F, the section is rather vague. Here's the relevant extract, page 18, table 1.5:

Mechanical intermittent extract

Intermittent extract can be operated manually and/or automatically by a sensor (e.g. humidity sensor, occupancy/usage sensor, detection of moisture/pollutant release). Humidity controls should not be used for sanitary accommodation as odour is the main pollutant.

In kitchens, any automatic control must provide sufficient flow during cooking with fossil fuels (e.g. gas) to avoid the build-up of combustion products.

Any automatic control must provide manual over-ride to allow the occupant to turn the extract on.

For a room with no openable window (i.e. an internal room) the fan should have a 15 minute over-run. In rooms with no natural light, the fans could be controlled by the operation of the main room light switch.

 

[Pete999]

Good evening all,

Has anyone ever installed a fan like this before?
The issue I don't know the best way to overcome is that if I wire each bathrooms SL to the fan it will back feed and turn the lights on for both bathrooms.

The best I've come up with is 2x contactors - one SL to each input - then both outputs to SL on fan isolator. L+N from both junctions straight to fan isolator.

Is there a better way of doing this?

I thought it would be a good idea as it is serving two small back to back en-suites, accessible loft space above for the fan. They are much more powerful than the standard wall/ceiling units. Plan was one duct out - Y joint at fan to each room.

The contractors will cost around £55 so unless someone knows a better solution it makes more sense to install two fans.. They cost £65 each

Thank you

What exactly are you trying to do as your post title mentions switching a fan from 2 positions, now it's 2 fans?

 

[S P]

Hi Pete,

Thanks for your time. It's one fan I want to control if practically possible. Ideally with timer over-run operated via SL from either bathroom.

The two fan's mention was me saying is it wiser to scrap this idea if it doesn't have legs...

 

[Pete999]

Hi Pete,

Thanks for your time. It's one fan I want to control if practically possible. Ideally with timer over-run operated via SL from either bathroom.

The two fan's mention was me saying is it wiser to scrap this idea if it doesn't have legs...

Configure the fan as a two way light and use 2 2way switches to control the fan

 

[S P]

Thanks. That would work, so the contactor idea is overkill then?

What you suggest isn't against any regs but Part F suggest:

"For a room with no openable window (i.e. an internal room) the fan should have a 15 minute over-run. In rooms with no natural light, the fans could be controlled by the operation of the main room light switch."

Would you write anything on the cert or not needed as you've complied with building regs: "There shall be adequate means of ventilation provided for people in the building."

FYI both rooms have no natural light

 

[Toneyz]

D.P.switch at each bathroom is the simplest way.

 

[jackhammerJIM]

Configure the fan as a two way light and use 2 2way switches to control the fan

I wouldn't do it like that .

 

[Des 56]

If you wire the fan as a 2 way,it can be switched off by the other user when you happen to want it left on
It would not have capability of a dinky little neon to tell if its off or on

If you wire as suggested with double pole switches,there can be no back feed to the other light because that would need their double pole switch in the on position as well to back feed to the light

The double pole switches can also have their very own dinky neon on the outputs

 

[Leesparkykent]

Double pole switch at each location. One side of the DP switch for light the other side for the fan.

 

[Richard Burns]

Little diagram of the suggestions above: DP switching.
Dashed lines show fan PL and SL.

 

[elsparko]

2 fans , why make a simple job harder

 

[Taylortwocities]

2 fans , why make a simple job harder

DP switch much easier. However, if you opt for two fans, sharing one extract duct then you'll need to consider the issue of air backfeed from one room into the other.
The last thing you want is Vindaloo poo from one room being pushed back into the other. To solve that you'd need two backdraft flaps in the two fan outlets, and probably a larger outlet duct after the Y piece to cater for when the two fans are going at the same time.



So two fans not so simple a solution.

 

[elsparko]

DP switch much easier. However, if you opt for two fans, sharing one extract duct then you'll need to consider the issue of air backfeed from one room into the other.
The last thing you want is Vindaloo poo from one room being pushed back into the other. To solve that you'd need two backdraft flaps in the two fan outlets, and probably a larger outlet duct after the Y piece to cater for when the two fans are going at the same time.



So two fans not so simple a solution.

2 fans, 2 ducts, 2 vents

bish bash bosh

 

[Taylortwocities]

Are you really an electrician, or a ventilation engineer.

2 switches (he'll need that anyway)
one fan (half the price of two fans)
Ducts and vents (he needs that anyway)
Cable (he needs that anyway)

what's not to like?

 

[S P]

Thanks guys - DP switch is how I'm going to go

Richard - thanks for the diagram that makes perfect sense now.
I couldn't visualise it - I was thinking people meant a 2g switch which wouldn't have turned fan on with light.

 

[elsparko]

what if a bird makes a nest in that 1 vent, thats 2 fans blocked

Are you really an electrician, or a ventilation engineer.

2 switches (he'll need that anyway)
one fan (half the price of two fans)
Ducts and vents (he needs that anyway)
Cable (he needs that anyway)

what's not to like?

both fans will always have to be on with eachother, save the planet bro, dont waste leccy

 

[Taylortwocities]

Eh? Me no understand.

With DP switch solution - and one fan - then there's only one fan to power, no matter even if both bathrooms are in use.

With two fans, its double the ice-cap melting power if both rooms are in use at the same time.

what if a bird makes a nest in that 1 vent, thats 2 fans blocked

Come on, get real. There's a vent grill on the outside.
But, I suppose that a squirrel could pull that off, crawl up the duct, unwire one of the fans and take it back to his nest. Then I guess its worth having a second fan in that case.....