I’d like an extractor fan that only works when there’s steam in the air.

My fan comes on with the light, and is therefore annoying when I go for a wee in the night, as inevitably I forget it’s still on until I get in to bed, when it’s whirring annoys me. If I turn off the isolation switch, I forget to turn it on for a shower and as there’s no window, I get a damp bathroom.

Your looking for one with. Humistat.

Lots have humidistats, most are however, crap.

Assuming you’re happy with doing the wiring put a timer in line with the fan so it only switches between 6am and 11pm or what ever.

Same problem for me and a humidistat was rubbish – Mine is connected to a Sonoff basic wifi switch and uses a timer in the app to only switch on during times we will be showering etc. The switch is only £5 and works a treat.

Wire a light to a PIR detector that will come on when you need it to, or buy a bathroom cabinet with a light in it that you can switch on for discrete use.

You need a small battery powered light, either a push-to-turn-on thing, or a proximity sensor one.

Keep light off, sit down, pish, back to bed.

Lots have humidistats, most are however, crap.

I’ve had two, both were crap.

I also had a PIR one which was only slightly better.

I have a timer one which Just Works.

I suspect that the margins on these things are so razor thin that only the really crap ones actually get produced by the giant factory in China they all come from.

Maybe you could make a really good one using a Raspberry pi.

Who turns on a light to pee at night? I stumble in, sit down and stumble back normally kicking the bed frame on the way!

Then you get the shock of the cold lav seat though nobeer.

As an aside i solve this problem by NEVER needing a slash at night. Am i doing it wrong?

Am i doing it wrong?

Yes

You need more beer

You’re not doing it wrong just not hit the right age yet!

We’ve a humidistat one, and yeah, I’ve not been impressed with it.

I wish the timers worked so that they had a delay start function, as well as an over-run.

Simply tie a length of dental floss round the loo seat, with the other end attached to the bathroom door handle.

When you need the loo in the night, find the floss tied to the handle; straddle the floss, facing the door; walk backwards, allowing the floss between your buttocks to guide you until your scrotum hits the toilet seat.

Sounds like a piss poor plan

Then you get the shock of the cold lav seat though nobeer.

True, but it’s better than pissing on your toes.

It only ever happens if I’m really brazen and have a second cup of tea anyway, a rare occasion.

#rocknroll

small battery powered light, either a push-to-turn-on thing, or a proximity sensor one.

Works for us. Mr Beams ones are under a tenner, run on 4xAAs that last a several months between charges. Just enough light for a nighttime bathroom visit.

We fit Zhendyr ones that have a fancy electronics, if you turn the light on and it’s not been on long, I think 5 mins, the fans stops again straight away, but if you have the light on for longer showering, then it’ll over run for a longer programmable period.

You wire them like a standard fan with L, SL and N.

Thought these things had an adjustable timer for how long the fan remained on after the light was turned out. Pretty sure mine does. Maybe you can’t turn it down to zero but maybe as low as one minute or something. Either that or sit down wee in the dark if you’re worried about missing in the dark. Works for half the population.

We have a humistat one and it’s been really good, it replaced a very old one which had a good life. If you get the adjustment right they do a very good job of keeping a bathroom dry and mould free. Ours only came on when running hot water or in the shower once adjusted correctly. Much better than one that’s linked to the light anyway. It wasn’t anything special just water axial fan screwfix had.

I can see it being a PITA if poorly adjusted or if you dry loads of towels in the bathroom as there’s a chance it would come on at night.

An utter nerd would have a little RasPi monitoring the humidity level and then switched the fan on when it was above a certain level – and switched it off once the humidity was below that level.

We fit Zhendyr ones that have a fancy electronics, if you turn the light on and it’s not been on long, I think 5 mins, the fans stops again straight away, but if you have the light on for longer showering, then it’ll over run for a longer programmable period.

You wire them like a standard fan with L, SL and N.

thanks – i’ll have a look!

TBH it’s not just peeing at night – it’s every time the light goes on (no window, WFH) – it’s just quite irritating, and using elec that doesn’t need to be used! I kinda need the fan to continue running for a little while, as that’s the only ventilation, and I like a long hot shower!

Get a night light for the bathroom, do you have a shaver socket?

An utter nerd would have a little RasPi monitoring the humidity level and then switched the fan on when it was above a certain level – and switched it off once the humidity was below that level.

One of these fans Manrose XF100H does exactly that for the princely sum of £29.99. If you wanted to make it fancier and AND gate with a clock that stopped it coming on at night would be cool.

An utter nerd would have a little RasPi monitoring the humidity level and then switched the fan on when it was above a certain level

Nahh, a proper utter nerd wouldn’t dream of designing such an over-the-top system 😉 They’d design a custom PCB with an ATTINY5 µC and DHT22 sensor. If there was a desire to have a web interface for such a contraption, you might stretch to an ESP8266 based design.

I feel a project coming on…

That looks what I’m after too Tom. We have an inline thing with an LED light in the middle, it is utter shite. Ceiling is that plastic channel lining stuff, I just know it’ll end up being one of those god awful jobs to replace.

We had a humidistat one fitted 6 years ago. Our plumber and electrican both warned against it saying they come on randomly etc. so we made sure we got one that could also run in timer mode if needs be.
Low an behold 2 days after fitting the fan was on pretty much permanently and I thought I’d made the wrong choice. However on further investigation, the ducting in the loft space was not insulated so in just 2 days had a litre of condensed water in it. After removing the water and putting some Rockwool over the ducts it’s been running perfectly. The one we have has lots of adjustments, including the humidistat sensensativity.

Nahh, a proper utter nerd wouldn’t dream of designing such an over-the-top system 😉 They’d design a custom PCB with an ATTINY5 µC and DHT22 sensor.

Nah for something simple like that its all about relay logic and or 7000 series chips and some RC timer

small battery powered light, either a push-to-turn-on thing, or a proximity sensor one.

Or a Nest smoke alarm, it has a motion sensitive LED light you can enable, we have one on the landing outside the bathroom.

As for Humidistats, we had one but only seemed to come on when it was raining outside and there was high general humidity, changed it for a timer triggered from the bathroom light.

I think most timed fans can be overridden by flicking the switch quickly. After i turn my light off a quick yank of the cord on, then off, and the fan stops. Same with my PIR outside light. I can override the sensor and switch the light on permanently from the switch by flicking it off then on from the on position. Try it, if it doesn’t work first time try doing it at different speeds as i get the timing wrong sometimes and i have to do it again.

I’ve just done this a month ago.

Using home assistant on a Pi3b, inline fan with duct inlet above shower.

ZigBee temp and humidity sensor in bathroom.

ZigBee door sensor on bathroom door.

Simple manrose inline fan in loft with sonoff ZigBee switch between fan and isolator.

Home Assistant programmed to monitor not the humidity but the rate of change of humidity to detect showering activity. Will switch on Sonoff if between 8am and 10pm and bathroom door closed. Means on a damp humid weather day the fan won’t come on if no-one is showering, but on a dry day with 45% rh fan will come on if someone has a shower. Fan usually triggers within 1min of shower starting. Home Assistant switches off Fan 15mins after bathroom door opened.

If humidity sensor breaks…another 12 quid or so to replace. May consider a ZigBee vibration sensor glued to underside of shower tray to get a slightly faster response though.

I am in the process of installing a remote bathroom fan with a separate humidistat today. I’ll report back when its fully installed

Using home assistant on a Pi3b, inline fan with duct inlet above shower.

ZigBee temp and humidity sensor in bathroom.

ZigBee door sensor on bathroom door.

@gwaelod nice, I’ve been messing around a lot with HA recently. If the goal is to recognise accurately when people are having a shower, would it be simpler to wire in an energy monitor into the shower circuit, to detect when the extra load starts/stops? I’ve just done similar with our (non-smart) washing machine, which is in an outbuilding. HA now pushes a notification to my Watch when the washing is done 😂 (I’ve been using Shelly stuff rather than Sonoff)

@zilog6128 I have a Shelly switching on my garage lights when I open the door, and another one in a drawer somewhere waiting on a project to be used in – they are quite cool!! Guess you could use current detection for an electric shower, although mine isnt electric powered and its hot water comes from the gas central heating boiler.

I think most timed fans can be overridden by flicking the switch quickly. After i turn my light off a quick yank of the cord on, then off, and the fan stops. Same with my PIR outside light. I can override the sensor and switch the light on permanently from the switch by flicking it off then on from the on position. Try it, if it doesn’t work first time try doing it at different speeds as i get the timing wrong sometimes and i have to do it again.

this is what i do – unfortunately i often forget to do so – hence my question!

Ok – its all wired up and working. Fan comes on within a minute or two of the shower going on, overruns for ten mins. Timer and sensitivity are adjustable. Fan seems nice and powerful

Only thing bugging me – both the fan and the humidistat have timer facilities on them and this meant the fan needs a live, a switched live and a neutral. I have had to take the permanent live direct from the spur unit leaving a neutral unused.

Edit – this is the fan unit and humidistat I used
https://www.screwfix.com/p/manrose-mf100t-25w-in-line-mixed-flow-fan/719gy

https://www.screwfix.com/p/manrose-1361-remote-bathroom-fan-humidity-control-with-timer/44376

What about a 2gang switch, one for the light and one for the fan. So you can switch the fan on independently to the light it will also have the run on after your mega long shower.

This thread fills me with gloom as I’m about to move into a new build that’s got these fans and so much else that’s wrong with it. This and overheating and the almost certain mouse infestation and all the other things that have gone wrong or are about to go wrong.

Mine appears to be working fine in both bathrooms. far superior to timed ones.

Our old fan didn’t come
On for a few minutes after the lights go on, so you can be in and out before it kicks in. New one fitted yesterday is very quiet so I’ve set overrun to max to try and move a bit more air, the upstairs can get a bit damp.