Tool for Solar Thermal System Schematic

Hello,

I've started down the road of putting together a drainback system for my house in sunny San Francisco. If you're curious what I'm up to, I'm documenting the process here: http://sfsolarhotwater.blogspot.com/

I'm at the point that I'd like to create some system schematics. I *love* the design of the schematics published in Homepower magazine, but I've struck out trying to find the tool HP uses or anything like it. What are you all using? I need to get this ugly, `key free' SRCC OG-300 diagram:

Into something with a proper `Key' and better legibility. Is there a Visio or OmniGraffle set of templates/stencils that are used in the industry?

Thanks in advance!

Marshall

Figured it out... Dia.

Didn't get much in the way of feedback, but figured out how to use Dia to do what I wanted to do. Here's a little write up on using Dia with the solar thermal template: http://sfsolarhotwater.blogspot.com/2012/01/schematic-first-pass.html