Extract Fan Controls

[Lankydan]

So I've bought an inline duct fan (http://www.solerpalau.co.uk/td-250-100-silent-230-240v-50-60.html) that needs to come on when the kitchen lights are on. The issue I'm having is that it also needs to come on when a humidity sensor (https://www.screwfix.com/p/manrose-1361-remote-bathroom-fan-humidity-control-with-timer/44376) detects that the humidity is too high.

Before knowing that I needed the humidity sensor, I was just going to power the fan by the switched live and neutrals in the lighting circuit.

How do I best incorporate these two control systems to power the fan?

 

[sparxxxx]

I doubt whether the humidity would ever get high enough to set it off. Just connect to the lighting circuit.

 

[Lankydan]

I doubt whether the humidity would ever get high enough to set it off. Just connect to the lighting circuit.

Unfortunately, my building warrant states it so I need to do it in order to achieve the completion certificate.

 

[Taylortwocities]

I was just going to power the fan by the switched live and neutrals in the lighting circuit

These will be ok to operate the fan. The humidity sensor will need a permanent live and neutral on the input. The output of the sensor goes also to the fan input.

NOTE: it is vital that the L&N to power the sensor is from the same lighting circuit.

As @sparxxxx posted, you aren’t going to get much joy with a humidity sensor as we live in a very soggy part of the World. Just connect it up to get your building warrant. You’ll be disconnecting it very soon afterwards!

 

[endecotp]

Have you looked at the wiring diagram that comes with the humidistat?

I believe it has an input for the switched live from the light.

 

[Taylortwocities]

Have you looked at the wiring diagram that comes with the humidistat?

I believe it has an input for the switched live from the light.

Correct. Just follow the instructions!!!

 

[Harry Bloomfield]

The (adjustable) humidity stat on both my bathroom extract fan and dehumidifier (drying clothes in my utility) work well enough. Both are adjustable for trigger humidity and the normal humidity varies between 45 and over 90% when the shower, bath or wet clothes are drying.

Aside from a humidity stat, I think in a bathroom/toilet a run on timer plus PIR are even more essential. You don't always have humidity or turn the light on when using the toilet.

 

[Lankydan]

Have you looked at the wiring diagram that comes with the humidistat?

I believe it has an input for the switched live from the light.

But wouldn't that be putting the switch and sensor in series meaning that you'd need both to have the fan running? I'd need the fan to run with the lights or with the sensor.

These will be ok to operate the fan. The humidity sensor will need a permanent live and neutral on the input. The output of the sensor goes also to the fan input.

NOTE: it is vital that the L&N to power the sensor is from the same lighting circuit.

Would that make a neutral loop on the same circuit though?

 

[Taylortwocities]

But wouldn't that be putting the switch and sensor in series meaning that you'd need both to have the fan running? I'd need the fan to run with the lights or with the sensor.

No no. They go in parallel!!!!
But, if you follow the wiring diagram for the sensor then it’s all done for you.

Would that make a neutral loop on the same circuit though?

So what? It’s the COMMON connection.
But, again. Wire the humidity in accordance with the instructions.

 

[endecotp]

Just follow the instructions.

What is a “neutral loop” ?