Hello,

I’m trying to winterize my irrigation system at my recently-purchased home, but I am confused by the backflow set up there (see attached jpg). There is no port to attach a compressor line on the outflow line (marked “to heads” in the photo).

I tried attaching to the compressor alternately to numbers 1, 2, and 3 after shutting off the water line in the crawl space, but the air seemed to just exit out the backflow valve on top. Thankfully, I don’t think I damaged anything trying this (note that there is another valve handle located behind the backflow device that is hidden in the picture).

At my prior home, a port was on the outflow part and I had no problem blowing out the system every season.

Should I install a port in the outflow pipe, or is there a way to blow out the system safely the way it is?

What am I missing here? Thanks.