Water Flow Switches

[ldoodle]

Wasn't sure where to put this - it's both water and electricity.

I want to have a water flow switch installed to power the shower fan/light combo unit whenever the showed head gets water.

We will have a 2 way shower valve installed - one outlet for the shower head and the other for the bath filler, so it seems it needs to go between the outlet on the valve and the shower head.

But, is something like this suitable for powering such a thing? This is the fan/combo unit I've chosen;

http://www.betterbathrooms.com/bath...ntilation/cyclone-chrome-wet-room-inline-fan/

And this is the sort of flow switch I found. Not sure on flow rate though;

http://www.pvl.co.uk/flow_switches_general_purpose/615_622_diy_flow_switch.html

How does it compare so something much cheaper, like this;

http://www.rapidonline.com/electronic-components/copper-flow-switches-75123/

 

[Blagard]

You need to be careful with that cheaper flow switch as it is rated 15W maximum. While the light/fan you have linked to has a low watt LED light the fan rating is unknown. I suggest you contact the supplier for further information

 

[ldoodle]

To be honest I probably wouldn't have gone with the cheaper one anyway - looks a bit pokey to me.

However, the other one states it's rating is 16A, so that rules out the traditional way of connecting the fan to the lighting circuit, and seeing as 16A fuses don't exist, what is one supposed to do?

Separate MCB for this gadget? Or is this just the maximum it will output?

 

[EFLImpudence]

16A is the maximum the device can carry, not output.

You can still use it to control a less than 1A fan and light.


Bit cheaper here
http://www.qssupplies.co.uk/bathroom-furniture-shower-taps/84198.htm

 

[ldoodle]

16A is the maximum the device can carry, not output.

Carry is what I meant!

 

[ldoodle]

Hey,

Bathroom has since been done and as I didn't want either a separate pull cord or to have the fan come on with the light, I've fudged it a bit for now by using the fan isolator as the actual switch for the fan!

Not great I know, and was never planned to be a long term solution.

So I'm back to looking at flow switches. The one I linked to on PVL.co.uk looks like what I need, but I'm struggling to envisage how it actually connects up.

My inline fan has run-on timer too. PS: I went with one without a light - it's just a fan.

The blurb on the website says it has 3 core cable. I would assume it's effectively a light switch, so a common live and switch live, with presumably the third core as earth.

So taking a traditional radial circuit:

NB: 4t junction box. t1 = live, t2 is earth, t3 = neutral, 4t = switch live

first light to junction box in t+e (t1 brown, t2 earth, t3 blue)
junction box to next light in t+e (t1 brown, t2 earth, t3 blue)
flow switch to junction box (t1 brown (common), t2 earth, t4 blue with brown sleeving (switch live))
junction box to fan isolator in 3c+e (t1 brown (permanent live), t2 earth, t3 black with blue sleeving (neutral), t4 grey with brown sleeving (switch live))
fan isolator to fan in 3c+e

With 3c+e is there a standard to using black or grey as neutral or live?

View media item 84774

 

[Blagard]

<snipped>
So I'm back to looking at flow switches. The one I linked to on PVL.co.uk looks like what I need, but I'm struggling to envisage how it actually connects up.

My inline fan has run-on timer too. PS: I went with one without a light - it's just a fan.

The blurb on the website says it has 3 core cable. I would assume it's effectively a light switch, so a common live and switch live, with presumably the third core as earth.

No the switch has a wiring diagram and is a simple switch using a common, NO and NC contacts (those 3). No mention of an earth terminal. So yes wire as switch but you will probably not need the NC (normally closed) terminal so 2 cores and your earth. You will need to terminate the earth sensibly if no terminal on the switch.

Your diagram looks OK for switch the fan using the flow switch to switch the fan with overrun. Noted no switching of the fan with light switches.

Sleeve both live and neutrals to show that is what they are. I am used to grey being a live (central heating controls) but so long as they are sleeved you are OK

 

[ldoodle]

No the switch has a wiring diagram and is a simple switch using a common, NO and NC contacts (those 3).

Yeah that is what I originally thought, but it sounded wrong in my head.

Thinking about it, I guess it means you can do 2 separate things: one when it's closed, another when it's open?

 

[Blagard]

I forgot to mention,

If wiring is likely to be near (closer than 50mm) to any hot water pipe use a heat resisting flex/cable.

And yes the switch allows two "on" functions, one when closed at rest, the other when active.

 

[ldoodle]

Good point about hot water pipes. I'd be piping it up to the shower head feed, which could be either hot or cold or somewhere in between.

Did you really mean 50 (fifty) mm. The only thing that would be anywhere near the pipework would be the cable pre-attached to the flow switch, which I would hope is already heat resistant!

 

[Blagard]

Yes 50mm or 2"

Edit, if close an alternative is to separate the heat source from the cable with insulation

 

[ldoodle]

One last question: can you get 3 core cable (flex or flat) without earth?

If you look at the diagram, the fan itself has no earth terminal, but I need 2 lives and neutral, so 2 core flex would be no good.

It would save me from having to leave the earth in a connector block inside the fan.

 

[Blagard]

You can use triple and earth cable without using the earth or 3 core flex. All with appropriate sleeves both ends.

 

[ldoodle]

Finally got around to installing this at the weekend.

Well worth the couple hours and £75ish it took. Just so much more convenient.

Can't believe it's not standard really, though I suppose it only really 'works' if everything is of the concealed type: where would it go if the shower head was on an exposed riser bar!!!

Thanks to all who provided input/assistance.