I'd like to use a computer program to draw both plumbing and electrical schematics. The program should be free or cheap. It must be capable of handling water to water geothermal, woodfired boilers, solar hot water and radiant hydronic hardware. What's available?

I would not trust any of these systems to a 'cheap' or 'free' computer program. Consult with real live 'experienced' providers of these services.

If you just want to draw, perhaps "Dia". It's free.

I'll check out DIA. Thanks. Any other ideas? I don't need any design help (from a computer)- that part's already done. I just want to be able to make neat/clean/clear schematics. Taco has a program I tried for a while for plumbing, but I found the program difficult and very time consuming to learn to use.