Issue replacing a bathroom extractor fan

[coliflower88]

Hi Forum,

Hoping you are able to help; today i removed our faulty Genie Nuaire fan and attempted to install a xpelair dx100h (http://www.screwfix.com/p/xpelair-dx100h-12w-axial-bathroom-extractor-fan-with-humidistat-timer/95442)

The extractor fan is currently wired to a switch outside of the bathroom to turn the fan on/off - the Genie was a pullcord model so we used to leave the switch on and just use the cord to start it. This new fan starts from the humidstat and its my understanding that by being on the switch, its 'always on' but only runs when required..

Anyway i've put the new fan on the wall, connected the 2 electrical cables (live and neutral) put on the shower to build some steam but the fan is not coming on? I've checked the cable with a multi-meter and can see power, as can i on the circuit board pcb of the fan.

Any help appreciated!
Colin

 

[PrenticeBoyofDerry]

You have connected to L and N on the fan?
There is also a humidistat setting on the unit that can be altered, I believe it is factory set at about 70%.
Could be worth linking out humidistat and connecting directly to overrun, to check the fan does run.

 

[coliflower88]

Hi, yep live and neutral are connected; there is also a T terminal, So L, N and T - are you saying move my red (live) cable to T instead?

I've adjusted the humidstat to min so should come in all the time but still nothing.

 

[JohnW2]

Hi, yep live and neutral are connected; there is also a T terminal, So L, N and T - are you saying move my red (live) cable to T instead?

The T terminal is for manual operation (with a switch), and does not need to be connected to anything for the fan to work in its humidistat mode. The installation instructions are not totally clear - the fan may come on if (for the purpose of testing) you just move the live cable to the T terminal, but it may be necessary for the live to be connected to both L and T (i.e. with a small piece of wire joining the two terminals). However, that's just for testing to see if the fan is working at all.

I've adjusted the humidstat to min so should come in all the time but still nothing.

That doesn't sound right it's normally possible to turn the humidistat down far enough for the fan to come on.

Kind Regards, John

 

[PrenticeBoyofDerry]

Hi, yep live and neutral are connected; there is also a T terminal, So L, N and T - are you saying move my red (live) cable to T instead?

If you connect to T this should then put the fan in to perm live, this would test that the fan does operate.

I've adjusted the humidstat to min so should come in all the time but still nothing.

Sounds problematic, I have installed the very same fan, and never had an issue with them.

 

[JohnW2]

If you connect to T this should then put the fan in to perm live, this would test that the fan does operate.

Do you know that from experience? As I just wrote, it's not totally clear from the instructions - they show connecting live to T for manual 'on' of the fan, but that's in a situation in which live is already (also) connected to L. I therefore wasn't sure whether or not L, as well as T (maybe just a trigger input, as on standard timer fans) need to have a live feed for the fan to come on.

I've adjusted the humidstat to min so should come in all the time but still nothing.

Sounds problematic, ....

Indeed - as I said, that doesn't sound right.

Of course, I suppose we're not yet absolutely certain that power is getting to the end of the cable! (I presume that the 'switch outside the bathroom' is on, and functioning properly!)

Kind Regards, John

 

[coliflower88]

Hi guys, tried it this morning and no amount of humidity turned it on, looking at the manual it doesn't look like just using the t connector will power it? Is it safe to try?

I've checked the cable at the end I wired into the fan using a multimeter and can see volts when the switch is on, and none when the switch is off so I know that's ok!

 

[PrenticeBoyofDerry]

Terminating to perm live, should be perfectly safe, providing you use safe isolation procedures whilst undertaking the work and you refit cover prior to re-energising.

 

[PrenticeBoyofDerry]

Do you know that from experience? As I just wrote, it's not totally clear from the instructions - they show connecting live to T for manual 'on' of the fan, but that's in a situation in which live is already (also) connected to L. I therefore wasn't sure whether or not L, as well as T (maybe just a trigger input, as on standard timer fans) need to have a live feed for the fan to come on.

I have never had to attempt this method on this particular model, but have done it on others and the process worked.
I do not see why connecting a perm live to T and not at L should prevent fan from operating, but if it does not, then further functional tests can be made via linking across L and T.

 

[JohnW2]

Do you know that from experience? As I just wrote, it's not totally clear from the instructions - they show connecting live to T for manual 'on' of the fan, but that's in a situation in which live is already (also) connected to L. I therefore wasn't sure whether or not L, as well as T (maybe just a trigger input, as on standard timer fans) need to have a live feed for the fan to come on.

I have never had to attempt this method on this particular model, but have done it on others and the process worked.

Fair enough.

I do not see why connecting a perm live to T and not at L should prevent fan from operating, but if it does not, then further functional tests can be made via linking across L and T.

You say that "you do not se why..." but my thinking was that what you suggest would not (without a link between L and T) work with any standard timer fan I've seen. The 'T' (of 'S/L') input on them is literally a trigger input, connected internally via a very high value resistance (typically 150kΩ - 250k&#937 to the electronics - so the power to run the fan (once triggered) has to come from the permanent live ('L'). Hence, as you know, if one wants the fan to come on, one has to apply 230V to both L and T (or S/L).

Kind Regards, John

 

[coliflower88]

Ok i'll give it a go tonight on just T, failing that I'll link the two and see what i get! hopefully some movement!

 

[JohnW2]

Ok i'll give it a go tonight on just T, failing that I'll link the two and see what i get! hopefully some movement!

Indeed. If the fan doesn't work with the live connected to 'T' OR with the live connected to 'T' and 'T'&'L' linked together, then (assuming power is coming out of your cable!) there is something wrong with the fan.

Kind Regards, John

 

[coliflower88]

Ok have tried live in T and neutral in neutral, switched on but nothing? I imagined this would make it perm on but should I try steaming up the room as well?

Any other tests I can do on the wire itself with the multimeter? I can see power but is it important how much perhaps?

I also replaced the unit yesterday as I originally thought the fan was the problem, is it possible I've got two duds?

 

[JohnW2]

Ok have tried live in T and neutral in neutral, switched on but nothing? I imagined this would make it perm on but should I try steaming up the room as well?

Indeed, you don't need any steam. Amidst the uncertainties, one thing is clear from the instructions - if you connect live to T, link T and L and connect neutral to N, then the fan should come on permanently, regardless of humidity. If it doesn't, and if electricity is coming out of the cable, then the fan must be duff.

Any other tests I can do on the wire itself with the multimeter? I can see power but is it important how much perhaps?

Provided there is 'mains voltage (probably 230V-230V between live and neutral, that's all that matters.

I also replaced the unit yesterday as I originally thought the fan was the problem, is it possible I've got two duds?

Very odd. As I say, provided the cable is supplying the required voltage, if the above doesn't work, then I can think of no explanation other than that the fan is duff.

Do I take it that you are sure that your connections to the fan are OK - i.e. that you are tightening the terminal screws onto the copper wire/core, not the insulation?

Kind Regards, John

 

[coliflower88]

Should mention at this point I haven't got anything to link live and t not sure if I have any spare wire! Should it work anyway? Can I use any cable?

Interestingly I didnt notice before that the light is now on with t and neutral connected but still not going.

And yes there is plenty of exposed wire to the terminals.