Winterize irrigation system - where to attach a compressor?

I have an irrigation system that I need to winterize. In the past I used to hire a guy who installed the sprinklers but since I already have the compressor and everything else I need, I'd rather save $70. I've seen him hook up the compressor somewhere on the back low but I don't know where. I was hoping that someone would be able to tell me where to attach it and if there is anything else special I would need to do.
Here are some pictures of my backflow:
http://www.medicfamily.com/tmp/DSC02319.JPG
http://www.medicfamily.com/tmp/DSC02320.JPG
http://www.medicfamily.com/tmp/DSC02321.JPG
Thanks!
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

How big is your compressor, mine is to small it has to little volume, the one my sprinkler co uses is a big unit towed behind their truck im sure if they only needed a small unit that is what they would always use.
What do you do to keep the backflow preventer from freezing, I see no lower drain provision, I remove mine it has a flange that unbolts easily and I dont see that on yours, where do you live and how has that been protected in the past as mine would have been ruined by now, its 19 this morning. I see a spigot on the pipe from the backflow, I will bet air goes there and clears the backflow out, if its gotten under 32f for any length of time already you will have a $350 junk backflow valve by now, and yours is not a 5 minute removal like mine. I would change that set up so you have 2 easy to unbolt flanges, if any water leaks past the interior shutoff it will settle at the bottom of the backflow and freeze if an interior line drain is left closed, mine leaks. My backflow was a 550 instal.
If it was my backflow Id sawzall off the valve at the vertical pipe and be safe this winter, and next year put on a quick remove flange, whare do you live.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I live is South Carolina - it doesn't get too cold but it definetely gets below 32F. I didn't do my winterization in the past - a guy that installed the system did it before so I am not sure how he did it. While he was there, all I could notice is that he attached a small portable compressor and blew the water out.
I have a 33 gallon compressor that should do the trick especially if the company was able to do it with a small portable compressor.
One thing I didn't mention is that I have a separate water meter and a separate line for my irrigation so spigot on the house is not fed from the same line.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've never seen a backflow valve that looks like that. On the 2 systems I've done myself, they were the PVC type and there was a regular PVC fitting with a plug on the supply side of the backflow. I take out that plug and use appropriate sized bushings to fit a male air chuck on it. That takes care of getting the water out of the backflow preventer. I don't know anyone that removes the backflow preventer, they just blow it out.
On your system, the equivalent point would be the right had side, but I have no idea what kind of peculiar fitting with the little screw is that we're looking at. Unless someone here is familiar with that valve, you could see if you can find a data sheet for that particular valve and figure out what it's all about. Of just pay one more time and watch.
Also, I agree with Ransley on the volume issue. I can do mine with a decent size portable shop compressor. Not sure how big the tank is, but it's one of the old craftsman horizontal tanks, with 2 wheels and pull handle like a cart. I can do mine OK with that, but I have 3 rotor heads per zone, maybe 5 smaller pop up heads on another zone, etc. I recently used it at a friends house and while we got through it, I doubt I'd do it again. He has a lot more heads, maybe 8 on some zones. It's very marginal, because there isn't enough volume. On a zone with 8, by the time you have 5 blowing air, so much volume is being lost that it then takes a long time to get the rest of the water out. Even when I do mine, I have to let the compressor build up to 80-100 lbs, then turn on the zone. I repeat that process until they are clear. On mine that is usually going through all the zones twice. On friends, I had to do that probably 10 times on some zones. It took probably 3 hours to get through all 10 zones. And while I have about 95% confidence level that there isn't enough water left to damage anything, I can't be really sure. The pros use a tow behind that can deliver VOLUME so it gets all the water out in one easy shot.
One factor that I could change is I've been using the 1/4" coil up flex hose on the compressor. NExt year I'm going to go to Harbor Freight and get a 25 foot bigger diameter straight hose. I would think that would help.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Nov 21, 8:04 am, snipped-for-privacy@optonline.net wrote:

Can you crank down the adjusting screws on all the heads and open them up one at a time, then close it and move on to the next? Start upstream and work your way to the end of the run.
Kinda similar to the way I winterize my cabin in Flagstaff, one faucet at a time. Done it that way for 8 years, haven't had a problem yet - except for the DUH moment when I blew the water heater empty without remembering to turn if off first - burned out both elements, but the pipes were fine.
Jerry
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Still, here we dont leave 350$ backflow preventers outside, address that issue before its 32 out, maybe a 33 gallon will work, attach to the hose fitting. You say it gets below 32, but does it freeze at pipe depth.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There is nowhere to attach the compressor on the hose. The copper pipes you see on each side of the backflow are solid and go into the ground. There is nowhere to attach the compressor on those pipes. That is why I'm confused. I looked up some information on the backflow and the procedure they are recommending is to attach a compressor on the pipe leading away from the backflow and close the valve on the left side of the backflow to prevent the air going into the backflow. The problem for me is that I have nowhere to attach it there - there is no fitting.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Just looking at it, I'd guess that you want to connect to the inlet on the left, so the backflow valve gets flushed in addition to the pipes. Close the left blue valve, open the screwdriver valve on the left and the blue valve on the right. Screw an air hose fitting to the screwdriver valve hook up the hose and turn on the air. I don't really know if this will flush the valve sufficiently.
If there are control valves for zones, operate each with air pressure applied to clear each zone.
You could look in the meter box for additional valves and fittings to allow you to flush or drain the pipe from it also.
Some sprinkler systems have automatic drain valves to avoid all this. Just turn off the water and open valves to relieve the pressure, and the automatic drain valves open to let the water out at the appropriate low spots.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I wasn't sure if you saw the arrow pointing to the left (meaning that water flow is from right to left). In that case, the backflow would not get flushed as you are suggesting. In addition, I read that you really should not run the air through the backflow. Is that true?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I wasn't sure if you saw the arrow pointing to the left (meaning that water flow is from right to left). In that case, the backflow would not get flushed as you are suggesting. In addition, I read that you really should not run the air through the backflow. Is that true?
I missed the arrow, so reverse my instructions. I'd call the manufacturer to ask about the air issue if that is a concern.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.