Bathroom extractor wiring - user error?

[greenfox]

Hi all, can anyone tell me what I'm doing wrong here?

I have a bathroom extractor with a humidistat and over-run timer (no pull cord). I would like the fan to come on when the humidity reaches 40% and switch off 10 mins after the humidity drops below this level - I've set the variable controls accordingly.

I have it on an isolated switch which is outside the bathroom, in a cupboard, and not linked to the light. (This would have been my preferred set up but I didn't want to go through the significant disruption to wire it to that side of the room).

There are 3 ports on the fan, marked L, N and L-T. From my switch, I have wired it like this
N : blue
L : brown
L-T : empty (there is a diagram next to it showing it's a switch from the L, unsure if that's a standard convention)

When I flip the switch outside the bathroom, the fan comes on and then switches off after 10 mins - as expected. Then if I turn the shower on, the fan comes on after a few minutes - but then it never switches off, even after the room is no longer humid. I had thought I could just leave the switch outside permanently on and then the fan would come on when it was humid, run for a while and switch off 10 mins after it no longer detects humidity.

Have I wired it wrong, or mis-read how it's supposed to work?

 

[HERTS P&D]

Try turning the humidity setting on the fan to the lowest setting.

ANdy

 

[greenfox]

Hi Andy, thanks for the reply. 40% is the lowest humidity setting so it's actually already set up like that. Does that mean you think it should work in the way I expected it to with that wiring...?

 

[DetlefSchmitz]

You might try joining the L-T connector to the L with a short length of wire. The switched live detector may be seeing spurious conditions if left disconnected.

Just an idea...

 

[cozycats]

Firstly you shouldn't be using the overrun in conjunction with an humidistat, and the humidistat does a better job once set correctly. You will need to experiment (for weeks!) to get the right setting on the humidistat. I would suggest starting the setting at 80% and if it does not run long enough decrease slightly (77%) until you feel its's doing an adequate job. They are very sensitive and a devil to get right. At 40% it's trying to dry the entire country out as our average humidity is near 70%.

 

[greenfox]

Hi there, thanks for the replies.

Firstly you shouldn't be using the overrun in conjunction with an humidistat

It came out of the box with these two controls built in - I selected option 4 when I bought it from these guys, seems they don't agree with you...

http://www.fantronix.com/acatalog/5__Fans_for_Small_Bathrooms_12v_Zone_1___2.html

our average humidity is near 70%

Ah. Well that would explain why it's never going to shut off if it's set to 40% then! I set it low to test that it came on quick enough after the shower was switched on (condensation issues in my flat) - stupidly hadn't even thought about the other side of the spectrum. Will do as you say, tweak the settings and see how it goes...

Thanks again - much appreciated.

 

[greenfox]

For some reason that link doesn't display - anyway it's one of the
Classic Bathroom Extractor Fans 5" dia, from Fantronix.

 

[greenfox]

You might try joining the L-T connector to the L with a short length of wire..

Thanks for the reply - think I'll try the other suggestion of tweaking the settings first - may resort to this later if need be!