"Lawn Guy" wrote in message ...
Chris Tidio wrote:

Tired of paying to have the sprinkler lines blown out every
winter, but I also don't want to have to replace lines and
sprinkler heads in the spring :-)

I've got a 7-zone sprinkler system at a small commercial office
building. Each zone has about 6 or 7 heads. Each time the system comes
on in the summer, every head in each zone belches air for about 15
seconds before water starts shooting out of them. This doesn't just
happen the very first time the system comes on for the season - it
happens every time the system comes on.

I'm thinking that the heads or the lines have an automatic drain
function that always kicks in when the system turns off, and therefore I
don't need to blow the lines out in the fall.

Comments?

You are most likely correct. A well designed system has no need for
compressed air. I live in Denver, and used to design and sell the parts for
irrigation systems. We always tried to design for gravity drainage of the
system. The common pipe for laterals here is polyethylene (poly) pipe. It
can take a lot of water frozen inside of it, as long as the pipe is not
completely full of water. One office building I had, the north zone in the
shade sometimes still had ice in the pipe when we would turn the system on.
It would melt out with no damage. That system was in use for well over
twenty years, until the highway department widened the road, and dug it out.
The sprinkler guys love to convince you that compressed air is required to
keep from freezing damage. My current home has a very old system, but it
does gravity drain.

Dale