Bathroom Fans

Has enyone used some sort of water flow detector (ON/OFF) to control the bathroom exhaust fans. When hot water is flowing turn on the fan until 5 minutes after the water stops flowing turn the fan off. I was thinking of something similar to the water flow detection in a gas hot water system.

I had previously been thinking of using a electrical thermostat attached to the hot water line but the temps in the roof space get as high as the hot water line any way. I had thought of using the humidity sensors mounted on the ceiling but there ugly.

Any ideas welcome.

Steve

 

steam sensor

At my house I have used a Vapotec Steam Sensors for the automation of my bathroom exhaust fan.

This is a unit that is just connected to the mains power supply. Its good as when it detects the steam it turns on and will continue running until the steam has cleared. Check out this web site.

http://www.cleverhome.com.au/products/Vapotec-Steam-Sensor.shtml

 

Thanks Noremac1,

I've seen the Vapotec Steam Sensors but I'm trying to keep the ceiling and walls as free of cluter as possible. And I'd rather have the fan turn on before the humidity was high enough to cause a film of water on the ceiling and walls.

Steve

 

You could use a flow sensor. they are used in ac control they have normally open and normaly closed contacts on them you would also need a coupler (5104bcl) to conect it to the C-Bus system. The only problem is that you have to get a pot put in to the pipe that it screws into and i am not shore if you can get them small enough to put them into a house hold hot water pipe but a mechanical plumber could tell you. I will ask at work tomorrow.

 

find a small temperature sensor (either 1 wire and interface via RS232 or use a GIU) and clamp it to the hot water line. Set the temperature at which the fan will turn on and a different one (possibly with a time delay as well) for turn off.

No modification to pipe work required.

Mick

 

Thanks Mick,

I had originaly though of using something similar, a 50 deg C N/O Thermostat Switchfrom Jaycar (ST3831) http://www.jaycar.com.au/productView.asp?ID=ST3831&keywords=thermostat&form=KEYWORD but the problem with that is it would be mounted in the roof space which in summer gets well over 50 deg C so that idea has been shelved for the moment. This comming summer I'll measure the roof space temperature to be sure.

And thanks SSuteboy,

Putting a brass fitting in the existing plumbing is not a problem as the house has been plumbed using Reahu's PEX pipe and fittings. I had planned to splice two 1/2" BSP brass tails inline with the hot water line going to the ensuite and bathroom (each room has a seperate feed). I was thinking of using a flow switch similar to those used in tankless hot water heaters, but thats where I come unstuck, I can't find any info on the type of sensor used etc.

Any help would be appreciated.

Steve

 

Steve

I have used both flow switches and temperature sensors to implement this sort of functionality before.

For the flow switch I have used RS Components' stock number 395-7173. It's adjustable and built to last. I tried some of their cheaper plastic units but they failed (to leak mode) after 12 months or so.

Previously I have also used a thermistor in a bit of heat-shrink tubing tie-wrapped to the pipe that runs from the mixer to the shower head. I used an op-amp as a comparator to drive a relay and do the switching. It takes a bit of fiddling around to find the right temperature but works well (unless you've got a masochist who enjoys cold showers in your household).

Have you thought about putting a solenoid valve between the mixer and the shower head? Switched via Cbus you'd be able to implement the "fan on if shower running" function but would also be able to have a "warm my shower for me" function.

HTH

Phil

 

Thanks Phil,

Thats along the line that I've been thinking, like the idea of being able to spend a few more minutes in bed before the shower water is warm enough. The RS flow switches are a little pricey and hence I was looking for a switch from a domestic tankless gas hot water system, the plumbers I've spoken with are not prepaired to help as they think its all magicand only plumbers have access to that magic circle, abit like Wiser dealers (this will come back to bite me)

Steve