Extractor fans, zone 0 and better sensors than humidistats

[SH]

Right....

I have a bathroom that has a 12 volt humidistat sensing extractor fan in zone 0

I also have a shower room with a 12 volt humidistat sensing extractor fan in zone 0.

the 12V transformers are in the loft above and access is trival. ditto to the ceilings of the two rooms concerned.

Now my problem is this, the humidstats are not very good, they do not always sense the steam, and when having an extra long shower, the fan turns off part way through.

Users of the bath or shower are not always veru good at keeping on top of the foibles of the extractor fan so I have a requirement to improve this so it is fully automatic.

Now my idea is this: to find a PIR ceiling sensor that (a) is safe for use in zone 0 to either switch 240 mains to the transformer or 12 volt supply to fan. (I can remove Humidistat sensing PCB and simply send 12v direct to the fan)

The PIR sensor would have to be within the bath or shower tray zone. Otherwise teh shwoer curtain will block teh PIR's view if it is mounted elsewhere.

I have windows in both rooms so linking to a switched live from the light fitting doesn't really work.

[Tim+]

Have you checked to see whether the humidistat has any adjustment? I had to take the covers off mine to find two hidden adjustments, one for run time when triggered by the lights and another for humidity sensitivity.

Tim

[SH]

already done all that...... :-)

mine is NOT triggered by light but by the onboard humidity sensor.

There is no timer as such on it, it supposed to start running when humidity rises above the set point and just keep on running until humidity falls below the set point.

[Tim+]

Maybe you just need a better brand of bathroom fan. ;-) Ours is very sensitive to rising humidity (it is within the shower enclosure admittedly) and runs for a good long period afterwards (since I adjusted it). Always starts within a few seconds of starting to shower. Ours isn’t linked to the light switch (as nobody needs a fan running for 5 minutes after every loo visit during the night).

I could imagine that a fan outside the enclosure might take a lot longer to start, particularly if it’s not already been triggered (by the light switch say) and not have anything to pull moist air through it initially.

Tim

[SH]

the two fans are inside the shower curtain and so in Zone 0. they do not always turn on automatically when we start showering. I have to pull the string on said fan to force it to start extracting.

It will then often cut out after a set time period irrespective of whether the shower has finished or not.

I am minded to replace both fans so what would you call a good make of humidity controlled 12 volt fans?

[Tim+]

Must be faulty then surely? No way should a humidistat be cutting out whilst you’re still showering. That sounds like it’s just running on its timer setting.

Have you checked to see that the humidity sensor isn’t covered in fluff/mould or other gunk? Just a thought.

Ours is an Awenta unit but it’s mains voltage. All I can say is that it works. Seems to be hard to find one with a humidistat now though. Does it have to be 12V?

Tim

[Max Demian]

Do they have fartostats for bathrooms with a toilet?

[chop]

The Philips Hue internal motion sensor is ideal for that situation. Battery powered with a battery that lasts for years with no wire connection to anything. Trivial to locate anywhere you like.

[SteveW]

What about a flow switch on the water and a run-on timer?

[ARW]

Unless the manufacturer states that their 230V fan can be used in zone 1 (OP slightly messed up his zones) then regardless of the IP rating it will probably have to be 12V.

[ARW]

Danlers do a IP44 PIR sensor. Model number CEFLPIRS. Mains voltage.

To use 12V you would probably need an alarm flush mounting PIR sensor but this would need a 12V DC supply to power the sensor and allow voltage free switching for the 12Vac the fan uses.

[Tim+]

I *think* ours is okay as it’s above 2.25 m off the floor (if I’ve understood zone 1 limits properly). Still think there’s something wrong with the OP’s humidistat if the fan is stopping whilst showering.

Tim

[ARW]

I have never liked humidistats.

My bathroom ran is on its own pull cord.

[Tim+]

Well I have the best of both really. I can switch it on manually or just let it fire up on its own when I shower. Seems to work pretty well and does do a better job of clearing humid air that a simple switch or timer.

Tim

[SH]

well the fan is definately in zone 1 and is actually within the curtilege of the shower curtain and is mounted on the ceiling, above the shower thermostatic mixer valve and wall rail.

I can actually touch the fan while stood in either the bath or the shower tray so thats easily 2.2m from bath/shower base up to ceiling.

well I am after a fully robust and automatic extraction with overrun timer control system as despite my verbal reminders, the other house occupants are forgetful.......

Excess humidity is going to lead to black mould.....

Oh that reminds me, I must order a new kitchen cooker hood as its cheaper for me to replace the whole thing rather than replace the two fans within!

[Rod Speed]

Trouble is that you have to go back later and turn the fan off after the fan has reduced the humidity to something better well after you have left the bathroom.

[Animal]

A flow switch plus timer would be hard to beat for reliability. Flow switch + humidistat would be nearer ideal.

[Animal]

extractor fans are pretty cheap. Hoods are basically oversize decorative covers

[SH]

That would mean ripping the bath out to then rip out the plasterboard behind it to then get access to the hot pipe and cold pipe that feeds the shower / tap mixer valve....

Even going under the floor outside the bath means ripping up the tiled floor, ripping up the No More PLy, then the floorboards then reinstating it all.

Then I have to run electrical cable from under bathroom floor or behind bath up to the loft area as that is where the 12 volt transformer is alogn with the switched live/supply from the lighing circuit.

[Theo]

Would the PIR work, or would hot surfaces confuse it? I suppose clouds of moving steam you do want to detect, but I wonder whether spraying hot water about going to cause either false positives or false negatives? eg it could detect for longer than you think if there's warm but cooling surfaces in the field of view. Or possibly not detect things if it has to turn the gain right down to compensate for things like hot pipes.

Would need some experimentation, I suspect.

Theo