Raspberry Pi to toggle 3-way valve

[Thomasdg]

I am planning to install solar heating for my pool but want to build my own control center for it. Normally those systems costs a lot and only thing they do is measuring temperature of water and rooftop and then open or close a 3-way valve to use the solar system only when it can actually heath the water (up to a maximum temperature of pool water).

The 3-way valve I bought is controlled with a 230 V system, normally by a relay in a system like a Minisol or Digisol.

Can the Raspberry Pi be used to activate/switch the 3-way valve, using (probably) a PiFace?
I am not the electronics or electricity kind of guy, more the programming kind, that's why I am so unsure about it...

Thanks in advance for any information!

[Statler]

Hi
I don't mean this to be a thread hijack but I'm looking at a similar project. I'm planning to control motorised valves and run my heating system using a Pi.

I've been looking at PiFace and Gertboard and can't decide which one is best for this application. I'm happy to share any info I find out.

My current control system is home brew based around 230v relays. I built this to control the various motors and pumps from a standard Danfoss three channel timeclock.

As well as running the current heating controls I'm hoping to add a cheap wind turbine which will heat a 48v immersion coil in a copper tank. I need to be able to open valves and turn on the pump to circulate the warm water in two underfloor circuits when the water reaches a certain temperature. Pi with a real time clock module sounds like the job. I can do in programming what I've had to do mechanically with the 230v relays.

I think we're looking at driving a low current 3v3 relay coil which will switch the 230v circuit. Maybe someone can advise?

Thanks
S

[PiGraham]

PiFace is an easy option that provides two GPIO controlled relays and stacks neatly onto the Pi.

On Danfos solenoid coil I looked at is 7.5W AC, 9.5W DC
What voltage and current do your devices require?
Are they within the ratings of the interface board?

[Knightlorish]

The PiFace is useful for the two relays to see how it all works but it needs some soldering to break out the GPIO pins to enable a 1-wire temperature sensor such as the DS18B20; it's only replacing the Pi header with longer pins and PiFace said that they'd be releasing a stackable version at some point. However, this way protected input is lost. The Gertboard's nice buffering of the input pins also needs to be bypassed to get at the bare GPIO 4 for 1-wire but at least it can be accessed directly without additional soldering. Opto-isolated relays can be had for not much money but they can be limiting in respect of current requirements in your power circuits.

Without hijacking the thread, does anyone know of how to connect 1-wire devices to the Pi with some protection should they go awry?