Smell sensor for fan

[Donkmeister]

I'm still planning my rewire, want to get it right!

In the bathroom, I was planning on installing a humidistat to control an extractor fan. I prefer this option over a timer fan because a) no fan-noise if someone gets up in the night and b) fan runs as long as it has to for eliminating humidity - should be less chance of a damp bathroom.

I've realised though... it doesn't do much for *ahem* smells! I've googled for "smellistat fan" but found nothing.

What I'm looking to do is find a way of setting the fan to go when someone's having a smelly sit-down. I've thought of a few possibles:

1) Use an "air quality" sensor - but I'm not certain these will work in that way
2) Use an occupation sensor with some sort of logic so if someone's in there for more than 5 minutes it turns the fan on and leaves it running for 10 minutes after they've left.
3) Fit a pressure switch to the seat so if it detects a bum on the seat for more than a couple of minutes it switches on the fan. (alternatively use a sensor on the door-lock)
4) A manual "boost" button that will get the fan going on full-pelt for 20 minutes - probably the simplest and most sensible solution involving just a timer and a momentary switch! I'd rather have something fully-automatic though.

Has anyone ever succeeded in solving this problem?

My house is generally the one everyone stays in after a night on the pop, so this is rather critical to my well-being... I never know when some pooligan is going to leave behind 8 pints and a vindaloo.

 

[electronicsuk]

Never seen such a sensor, but to me you're creating a problem that doesn't exist. Wouldn't a ducted van in the roof void be a better solution? With something underneath it to dampen any vibrations transmitted to the building structure it should be nearly silent. Failing that, you can buy fans in acoustically controlled enclosures.

 

[breezer]

many years ago i looked into it, you need a Gas detector, unfortunatley they detect all gasses and need some extras kit to sense just methane and they are not cheap. needless to say i never went any further

 

[Donkmeister]

Ah, it's not just a matter of buying gas sensor and using it as is then.

So, it sounds like IF I can get all the bits to do it (methane sensor) it would be expensive and a rather time-consuming activity to get working.

Or, I could just go for a humidistat controlled one and buy an air-freshener...

Thanks guys!

Perhaps I'll try one of the acoustically-controlled fans that electronicsuk mentioned and use a combination of timer and humidistat. The fan will run until x minutes is up AND humidity is at y%.

 

[ban-all-sheds]

2) Use an occupation sensor with some sort of logic so if someone's in there for more than 5 minutes it turns the fan on and leaves it running for 10 minutes after they've left.

That seems the easiest - PIR to trigger a countdown timer.

 

[mattylad]

you could always open a window, or leave a box of matches on the cistern

 

[Donkmeister]

Oooooh!

http://www.vent-axia.com/products/viewaccessory.asp?ProductID=3

Automatically reacts to the depletion of air quality, sensing tobacco smoke, smells and toilet odours to regulate mechanically ventilated areas

Toilet odours!!! I'll have to give them a call.

PIR sensor to trigger timer, that would work... then it's not relying on someone turning the light on first.

Two sensors and a timer just to control my bathroom extractor!!!

 

[Donkmeister]

you could always open a window, or leave a box of matches on the cistern

Ah, so when they strike the match, it triggers a thermal fire detector, which then powers up the boost fan, thus sucking all the nasty niffs out of the bathroom, and the draft then extinguishes the match thus removing the need for a timer?

 

[sparkyspike]

Donkmeister? Anyone who speaks German knows what that means! Are you sure you're not the Stinkmeister?

 

[Donkmeister]

Donkmeister? Anyone who speaks German knows what that means! Are you sure you're not the Stinkmeister?

Well, after all those bratwurst and enormous flaggons of beer my leiderhosen do get a bit ripe... DAMN gave the game away!

 

[TicklyT]

Just a thought.... Put a float operated level switch in a dual flush cistern. Half flush doesn't lower the water level enough to trigger it, but a full flush does... ?

 

[Taylortwocities]

These fans have two speeds, maybe run it on slow speed when the light is on and have a "boost" button on a timer for the post Vindaloo events (excuse the pun).

http://www.tlc-direct.co.uk/Products/SLTDK160.html

 

[sparkyspike]

The 'boost' button could look something like this: http://www.gogo-gadgets.co.uk/ekmps/shops/gogogadgets/images/fart-alert[ekm]90x90[ekm].gif

 

[breezer]

solved

 

[Chri5]

Glade do a Sense and spray unit, placed near the cistern that will spray on movement (not bowel operated).