According to Lionel C. Abrahams :
Scott wrote:
I know this subject has been talked about at great length in these
forums/groups. But I still do not have a good answer to my question.

I am planning on blowing out my own sprinklers this year. Looking
through all the forums and instructions I can find on the subject, I
have found conflicting advice. Some sources say DO NOT blow out through
the "Testcocks". So, this leads me to my question... where do I hook
the compressor line to?

Here is an image of my valve:
www.sacreativeservices.com/forum_stuff/febco.jpg

Do I hook to A? B? or C? it seem like C is a bleeder valve of sorts.

I observed mine getting blown today. My setup is similar to yours
without "C".
The company who installed the sprinkler system did the work. They
used "A" to blow the sprinkler lines, and "B" to blow the supply line
back inside the house with the drain opened inside, and the supply valve
shut.

Take the picture, omit A and B, and install a hose bib valve instead
of C. That's what ours is.

To blow the lines, I close the valve inside the house, and connect
the airline to the hose bib. I manually open each zone valve in
turn, and blow the segment out thru the sprinkler heads.

Once done, I remove the airline, and let any water remaining in the
feed line drain out the hose bib.

Done.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.