Humidistat fan

Merlin5 · 19 May 2021

Hello chaps. I bought this fan a few weeks ago from Toolstation to replace my old one which stopped working and it's installed above the shower.

https://www.toolstation.com/airvent-100mm-selv-12v-low-profile-extractor-fan/p74009?searchstr=74009

It works and in the first week or so it would come on by itself when it detected humidity. Recently though it's not been coming on by itself and I've had to pull the cord to switch it on. Then it'll switch itself off later on as I presume it's meant to. I've taken a photo of it and there doesn't appear to be a humidity adjuster as per the instructions. I was going to try and adjust it clockwise to lower the humidity threshold. Maybe since the weather has changed perhaps it doesn't think there's enough humidity. Or else I'm wondering if it's faulty or not. Just a note, my electrician friend installed it and tested the transformer outside from my old fan which looks identical and he said it's fine, so we didn't swap it for the new transformer. But I doubt that would make a difference to detecting humidity?
Any idea how to proceed? Thumbnail photos are clickable to enlarge. Thanks.

JohnW2 · 19 May 2021

Merlin5 said:
... It works and in the first week or so it would come on by itself when it detected humidity. Recently though it's not been coming on by itself and I've had to pull the cord to switch it on. Then it'll switch itself off later on as I presume it's meant to.

I'm not sure I understand that - how have you got it wired?

If the pull switch were wired to 'over-ride' the humdistat, it would stay on permanently after you pulled it (until you pulled it again), and would not "switch itself off later on". On the other hand, if the pull switch were switching the power to the fan+humidistat as a whole, then it would never have worked when the pull switch was 'off'.

Kind Regards, John

Merlin5 · 19 May 2021

JohnW2 said:
I'm not sure I understand that - how have you got it wired?

If the pull switch were wired to 'over-ride' the humdistat, it would stay on permanently after you pulled it (until you pulled it again), and would not "switch itself off later on". On the other hand, if the pull switch were switching the power to the fan+humidistat as a whole, then it would never have worked when the pull switch was 'off'.

Kind Regards, John

I'm afraid I've no idea how it's wired other than he just took the existing wires and connected to the fan. I don't think he changed anything as the old fan was much the same. As things are now, I'd pulled the switch this morning which turned the fan on and a while later it was off. I've just gone and pulled it again and it's switched on again and I'm going to see when or if it goes off.

JohnW2 · 19 May 2021

Merlin5 said:
I'm afraid I've no idea how it's wired other than he just took the existing wires and connected to the fan. I don't think he changed anything as the old fan was much the same. As things are now, I'd pulled the switch this morning which turned the fan on and a while later it was off. I've just gone and pulled it again and it's switched on again and I'm going to see when or if it goes off.

That's hard to understand, unless it has somehow been wired so that pulling the pull switch just 'triggers' the fan to come on for a period.

Do I take it, from what you say, that having pulled the switch this morning (which caused the fan to come on for just a while), the next time you pulled the cord the fan came back on again?

Kind Regards, John

AdrianUK · 19 May 2021

JohnW2 said:
That's hard to understand, unless it has somehow been wired so that pulling the pull switch just 'triggers' the fan to come on for a period.

Do I take it, from what you say, that having pulled the switch this morning (which caused the fan to come on for just a while), the next time you pulled the cord the fan came back on again?

Kind Regards, John

I think the OP means the pull cord that is part of the fan and not a separate pull-switch. If you zoom in on the OPs attached image, you can see what appears to be a pull-string attached to what I think is a momentary switch. I suspect that this provides a trigger pulse to the electronics.

I would also suggest that the PCB mounted potentiometer, situated just above were the group of red wires connect to the PCB, is either an humidity threshold adjustment or a time adjustment.

JohnW2 · 19 May 2021

AdrianUK said:
I think the OP means the pull cord that is part of the fan and not a separate pull-switch. If you zoom in on the OPs attached image, you can see what appears to be a pull-string attached to what I think is a momentary switch. I suspect that this provides a trigger pulse to the electronics.

Ah, yes, I think you're probably right. However, the bits of the instructions we've been shown don't seem to say anything about what that pull switch does - but you are probably right.

AdrianUK said:
I would also suggest that the PCB mounted potentiometer, situated just above were the group of red wires connect to the PCB, is either an humidity threshold adjustment or a time adjustment.

Again, I agree - but I would guess that it's probably a humidity threshold adjuster, since the instructions do not seem to suggest that there is any 'timer' functionality to the humidistat model - merely saying that the fan will "turn off when humidity falls". The OP therefore probably needs to twiddle that.

Kind Regards, John

Merlin5 · 19 May 2021

Thanks Adrian and John. Adrian, I think you're onto something. Are we looking at this as the humidity adjuster?

edit: I just answered my own question as I've just put a screwdriver in the slot and turned it fully clockwise which should make it come on at 65% humidity. I'll have to see if it makes any difference. If it still doesn't come on by itself during a shower, then I don't know.

JohnW2 · 19 May 2021

Merlin5 said:
Thanks Adrian and John. Adrian, I think you're onto something. Are we looking at this as the humidity adjuster?

As you've discovered, yes, that's what Adrian was referring to!

Merlin5 said:
edit: I just answered my own question as I've just put a screwdriver in the slot and turned it fully clockwise which should make it come on at 65% humidity. I'll have to see if it makes any difference. If it still doesn't come on by itself during a shower, then I don't know.

Let us know! I've never had one myself, but from what I've heard from others, I'm far from convinced that these humidistat-controlled fans are really much good - you might have to get a 'good fugg' going in the room for it to switch on

Kind Regards, John

Merlin5 · 19 May 2021

JohnW2 said:
As you've discovered, yes, that's what Adrian was referring to!
Let us know! I've never had one myself, but from what I've heard from others, I'm far from convinced that these humidistat-controlled fans are really much good - you might have to get a 'good fugg' going in the room for it to switch on

Kind Regards, John

Yes, I think a good fugg in the bathroom is required.

JohnW2 · 19 May 2021

Merlin5 said:
Yes, I think a good fugg in the bathroom is required.

Have fun

One of the questions is what you are wanting/trying to achieve. If 'condensation' is your main problem, then that arises when moist (humid) air hits a cold surface - so avoiding that is as much to do with keeping the room as a whole warm as it is to trying to remove mosit air.

Kind Regards, John

studentspark · 19 May 2021

Only install Humidistats fans if you like call backs.. Hopeless.

Merlin5 · 20 May 2021

Well guys, it didn't make any difference.

I'm going to see if I can get a replacement, though I'm not sure I have the receipt. Looking at my photo in the opening post, as far as wiring, it looks like I just need to unscrew the two wires coming out of the hole at the top right and re-screw them into the replacement fan? Also, do you think it makes any difference not having swapped the transformer over? I presume it wouldn't work at all if the transformer was broken.

The fan works fine but it just means I have to pull on the white string to turn it on and off. But it used to turn itself on during taking a shower. And as I mentioned, I pull on it, it turns the fan on and goes off by itself. Then I can pull again to turn it on, and again it will switch itself off later. Whether it's turning off due to lack of humidity or just because it's set to turn off after a certain time I don't know.

JohnW2 · 20 May 2021

Merlin5 said:
Well guys, it didn't make any difference. I'm going to see if I can get a replacement, though I'm not sure I have the receipt.

Maybe not logical, but have you tried turning that adjuster fully in the other (anti-clockwise) direction?

Kind Regards, John

JohnW2 · 20 May 2021

studentspark said:
Only install Humidistats fans if you like call backs.. Hopeless.

If, as seems to be the case, they have felt it necessary to include a pull switch to trigger the coming on of the fan, that doesn't speak well for how effective the humidistat control is!

Kind Regards, John

Mottie · 20 May 2021

I’ve had a humidistat / timer fan in my bathroom for a good few years and I’ve found it fine. By the time I’m halfway through a shower, it’s running. I also have the switched live going through a separate pull cord within reach of the WC with an on/off indicator in case I want to switch the fan into timer mode when I’ve, err, left a bit of a hum behind in the bathroom.

Pull the cord to start the fan then one more pull to disconnect the switched live and let the timer take over. Also means the fan doesn’t automatically come on if anyone switches the bathroom light on in the evening or middle of the night if they just have a wee.

https://www.discount-electrical.co....r---adjustable-humidistat-100mm---4-inch-230v

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Humidistat fan

Similar threads