dadgaume,
One thing to remember is that when you install automatic drain valves the water will drain out of the entire system everytime the water is shut off. You need to make sure that the area were the drains are can handle all of this excess water. From what I have read some people make sure the system drains into a ditch, well, or someplace they don't mind it being to wet. Also, this will increase your water usuage slightly since the entire system will have to fill up again prior to use. With my new system that I'm planning on istalling I opted not to have drian valves but I will have a little compressor that can blow air through the system basically running it on air and pushing all the water out of the system. If you don't think that you will remember to drain the system before the first frost then go ahead and put the valves on. If your tidious about these things like I am then this won't be an issue. You can also hire someone for a small fee to drain out the system for you. Also, make sure that you put a drain on each section between heads since water cannot flow through the head when its closed. Hope this helps a little
