instant HWS control input to cbus?

I noticed the other day that whenever I turn a hot tap on in my bathroom the burner led on the hws control panel comes on which got me thinking that I would much rather automate the bathroom fan when the hot ater is running then from the current PIR. (since on the other side of the wall behind the hot water controller is the cbus enclourse - in the closet)

so has anyone done this or considered it before. i figure that is if could wire the led contacts to a L5504AUX unit then i could turn the fan on when the hot water is running.

anyone?

 

Great idea, and no reason you couldn't, although you may or may not need to remove the led from the panel.
Also, be careful about isolation, use an appropriate cable (insulation breakdown voltage, and heat resistance).

 

Bathroom Fan

I've done this in several ways in the past on different projects.

As it's usually only the bath or shower that causes sufficient steam to warrant the fan use, I have detected flow to these. I originally used a flow switch plumbed into the pipe that runs to the shower head but I've not found these terribly reliable. I now use a thermistor zip-locked onto the pipe and some logic to detect the temperature rise.

You can then do fancy stuff if they're interested in it. eg pulse the lights once the shower is warm, only run the towel rail for n hours after each shower to dry the towels.

This method saves hacking into the boiler and doesn't cause any isolation problems.

Don't forget to give them an override for the fan somehow. It's not just steam that one needs to extract from a bathroom....

Phil

 

Any optcoupler taped to the LED display will do. A true Rube Goldberg machine.

Steam > Electrical > Optical > Sensor > Electrical > Mechanical > Data > Mechanical > Electrical > Motor > Remove steam

Just a shame that Clipsal doesn't have any C-Bus dominoes.

Might consider putting the fan and the light on a PIR with a 5min run-on for the fan.

 

I too have used flow switches Rinni had one for their infinity range of HWS to limit the temperature to bathrooms. I found this to be reliable after making a small hole in the flap to stop the water hammer when the water was shut off. They have stopped making them now but your idea is good.

Do you have issues on PVC pipes ? how long does it take for the sensor to go off after the shower is finished. Latent heat in the pipe and water.

Charles

 

I didn't think PVC pipe was allowed to be used for hot water?

 

The issues I have had with flow switches are limescale accumulation interfering with the magnetic float and cheap plastic housings that eventually start to perish and leak.

Only ever seen copper, so haven't had a problem here and don't know how it would work. Given that response time is not critical I would not expect too much trouble.

Using a "Once temp>X then pulse fan on for 30mins" type logic gets around this. X can take a bit of fiddling with to find a temperature that works. Remember that ambient in the UK is only 25 degrees tops. I imagine that in Australia there may be times when the thermistor might detect a hot day instead of a hot shower.

Phil

 

Not sure if you are talking about a specific country-region, but my house was all done in plastic - hot and cold.

My understanding is that there is nothing dictating that copper be used - I am not a plumber so I dont really know much.

Mick

 

I'm no plumber either, just thought I had heard somewhere that hot water had to be in copper. and never seen pvc used for hot water before, but ou learn something new every day