According to Paul A :

"Joe Blo" wrote in message
om...
I live in an apartment where the shower can take quite a while for hot
water to flow through the shower head and the temperature to
stabilize. I already have my coffee maker & towel warmer on an X10
home automation system.
I am searching for a plumbing attachment that attaches the end of a
shower head that has an electrically actuated valve (low voltage DC)
to allow water to flow so I can interface it to my home automation
system via a DC adapter.
This will allow my shower to automatically start in the morning.
To those who are lacking electricity knowledge, I am not at all
talking about using dangerous voltages near water. So please dont
misunder my post.

You might find what you want in the area of underground lawn sprinklers
which use valves similar to what you are asking.

Most of those are 24VAC. Will work on 24V DC, but likely not on 12V.

I'd avoid voltages even as low as 12V _inside_ the shower.

While it's not likely to be lethal, under those conditions you can
probably feel 24V. And maybe even 12V.

The valve should be outside the enclosure.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.