I was thinking of blowing out my own sprinklers this year because it seemed pretty straight forward and I am handy enough to do it. I get the basics: shut off main water, connect air compressor to system, open one zone at a time. Here is a picture of my backflow system. From what I would assume, I would turn off the valve to the right (probably the main shutoff), keep the valve on the left open and make an air compressor fitting for the pipe coming off of it that is capped currently. Does this seem correct? This is the box the sprinkler people go to for spring and winter maintenance. enter image description here

enter image description here


Your plan seems reasonable.

Some things to note:

  • The four little stubs sticking off the bottom are valves - probably ball valves. They could have water trapped inside the ball, so you'll want to blow those out and/or leave them open when you're finished to prevent the valve itself freezing.
  • The main valve is also a ball and will have water inside it too. There should be another valve somewhere in a freeze-proof location -- either inside the house or a few feet below ground out in the yard. It's find to close the right-hand valve here while doing the blow-out, but you'll want to leave the upstream valve closed and this one open when the job is finished.
  • Thanks! I found the other valve I can use a curb key to turn off. So do you recommend just turning that off then drain the ball valves/overflow, then blowout the system with my compressor at 50psi – Packy Oct 19 '20 at 20:03
  • That other valve may be a stop-and-waste type, which means it'll bleed water (and air) out of the sprinkler system. That'll make it difficult to blow the system out. So close the curb valve and the input valve on the anti-backflow assembly, do all the blow-out, then re-open the backflow's input valve. 50 psi is a great choice; that should minimize the chance of undesirable "sprinkler rocket" incidents. – Greg Hill Oct 19 '20 at 20:37
  • I tried turning my curb key (see new image) clockwise to shut off the system like have done in my old house, but the tube fills with water? Is this not the shut off but maybe some kind of bleeder line? Or do some shutoffs bleed water when turning? – Packy Oct 20 '20 at 19:41
  • @Packy "stop-and-waste" means the valve stops the flow of water from the supply to the outlet, and it wastes whatever water was in the outlet pipe. The water in the outlet pipe is wasted, ie allowed to drain away. If your valve is the stop-and-waste type, rather than an ordinary stop valve, this may be why the tube fills with water. Give it some time (appropriate for your soil type) to drain away. If the water remains longer than it should, or continues flowing unreasonably, then you could possibly have a valve failure of some sort. – Greg Hill Oct 20 '20 at 19:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.