irrigation

[chrisagh]

i'm new here and have a minor sprinkler problem. on a particular valve I have 6 sprinklers hitting a long planter bed area. all is great except when the valve shuts off two of the sprinkler heads leak a bit. they are not cracked or broken, but water seeps up between the body and the pop-up stem. i'm using a Rainbird 1800 series body and separate screw-on Rainbird heads. Has anybody dealt with this? The valve IS shut off all the way. And I dug up and raised the sprinkler at the lowest point and it still seeps. Any thoughts are appreciated.

[pushkins]

The ONLY way water can continually get the the heads after the valve is cycled off is a leaky valve/solenoid.
When the valve/solenoid is told to turn off by the control panel an electrical feed is removed this causes the valve to spring shut stopping the water going past the valve. Now when this happens the entire irrigation line is full of water and this can amount to a reasonable amount, now this water isn't under pressure so it slowly leaks out of the lowest valves. A simple formula is .75 (3/4") x 3.14 (Pi) x length of pipe in inches = volume

Do your heads leak over the continually ? if so it's the valve solenoid, the heads themselves are not water tight.

[chrisagh]

Thanks for the info. It seems that it's just the lowest heads that have water coming through. The water is coming out at the slowest rate it seems, but I'm concerned because it seems continuous.3 of the 6 heads, which are the highest, are totally dry. Hmmm. So, I should check the actual valve I guess, huh?
How do I check the solenoid?

[pushkins]

Remove the lowest head from the irrigation line, the water in the line will obviously flood out, it might make it easier to dig a hole near the removed head to give the water somewhere to go. The water should stop flowing (again this might take a little time as there is a reasonable amount of residual water remaining in the line) make sure your sprinkler system or at least this line is turned off. If you have a compressor you could blow out the line from another removed head. Either way the water should stop running out of the lowest head.
The solenoid comes apart usually by 4 s/s screws be very careful you don't want any dirt etc... in there, from experience IMO it's usually not worth trying to repair a valve if that is the problem, for $12 you can buy a whole new one.

[chrisagh]

thanks. I'll look into it. I did dig out the lowest head and put an extender on the riser to get it up another inch. Water stopped flowing pretty quick once I took the head off. I will try replacing the valve and see what happens.
Thanks for your help.

[pushkins]

Well if the water "stopped" flowing then there isn't a valve problem !! it's just the line raining out to the lowest point.

[chrisagh]

That's what I was thinking but wasn't sure. I think that's good news, but I still have an ultra slow leak. Will this always happen if one or two heads are lower than the others on a given valve? I'm going to be doing my backyard before I put in my lawn and want to try to prevent this if possible.

[pushkins]

Valves don't tend to leak a little they tend to simply stay open or open enough that enough pressure comes through to give the heads a good spurt of water.