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tatums4 06-05-2011 05:26 PM

Irrigation valve low pressure

I have a 4 zone Rainbird irrigation system. Two valves are side-by-side on the left side of the house and two valves are side-by-side on the right side of the right.

Had a lighting strike last year that took out the control panel and two valves on the left side. Replaced the control panel, and solenoids on both valves. Both zones came back up with full pressure.

Had a recent lightning strike on the right side of the house that took out the control panel and valves. Replaced the control panel, and solenoids on both valves yet only have low pressure as opposed to the full pressure that I had when I did this last year on the left side of the house. Go figure!

I took the diaphram out of both valves and checked for dirt/debris. I also ran the valve with the solenoid off to clear any blockage. Still, low pressure.

Just bought replacement valves from Home Depot yet hate the thought of having to dig out all the dirt around the valves and then do the cutting and then re-glueing of the pipes leading into the new valve.

Please tell me there is an easier way to fix this problem!!!!!!!!!

Thanks much!!!!!!!!!!!!!


downunder 06-06-2011 04:22 PM

You have low pressure at the valves or low pressure at the heads? Work your way from one end to the other and try to isolate where your pressure problem begins.

Some folks say I have a good imagination but I could even see having a line bursted somewhere along the way.

tatums4 06-06-2011 05:12 PM

Thanks for the reply!

The heads have a hard time popping up and when they finally get out, the water pressure coming out of them is low.

downunder 06-06-2011 06:21 PM

How is pressure at the valve?

tatums4 06-06-2011 06:41 PM

That's a good question!

How do measure the pressure at the valve?

Thanks, again!

downunder 06-06-2011 07:22 PM

You could get a pressure gauge for $10 but I was thinking of a general comparison of how strong it seems to be at each valve. Just open each as you would for flushing it out and see if all seem to flush about the same. Basically just a process of elimination to see where the blockage/leakage, etc is.

user1007 06-06-2011 08:14 PM


Originally Posted by downunder (Post 662176)
Some folks say I have a good imagination but I could even see having a line bursted somewhere along the way.

Not sure you are imagining. It sounds like a cracked pipe or something and dirt, sand or whatever has gotten in to keep the heads from popping up?

Lightning should not be causing pressure problems if you replaced the electrical components. Do run the valves manually with the little bleed screw.

ClassicLighting 06-06-2011 08:48 PM

Regarding the valve exCHANGE, just replace the guts. Beware of all the crapola that comes from Home Depot. Install a quality valve such as a Rainbird DV series or a Hunter PGV series.

tatums4 06-11-2011 05:27 PM

Latest on low pressure for 2 zones
Thanks for all the replies!

Here's the latest: I flushed/cleaned out both valves and replaced the diaprhams in each valve. YET, and that is a big YET, both valves/zones still have the same low pressure!

Sooooooo, here's my question again: After a lightning strike on a tree on the right side of the house wherein 2 of the valves (out of 4) are located within 10 feet of the tree that was hit, those 2 valves/zones have low pressure. After the lightning strike, I replaced the control panel, and the solenoids on both valves, (which solved the same problem I had on the left side of the house when lightning hit a tree last year on that side!).

Sooooooo, why would, last year on the left side, replacing the control panel and solenoids solve the problem, yet this year on the right side, doing the same thing does not solve the low pressure problem?

Thanks, again, for everyone's help!!!!!!!!!!!!!!!

downunder 06-12-2011 05:05 PM

My apology here but somehow I read your original question that you had low pressure on the right side only.

So, just to be clear when you say "both valves/zones still have the same low pressure" do you mean the right side zones or all four zones? At the risk of sounding dense, exactly where do you have low pressure?

tatums4 06-12-2011 05:26 PM

Hey downunder, thanks for all the help!

My 4 zone system consists of having 2 valves on the left side of our house and 2 valves on the right side of our house.

The lightning strike that hit one of our trees on the right side of our house blew out the irrigation control panel in our garage and also blew out the solenoids on each of the 2 valves on the right side of our house. Hence, after replacing the control panel and solenoids for each valve, the 2 zones they control started working yet each zone had low water pressure coming out of the heads.

Since the 2 valves on the left side of our house and the zones they control work with full pressure, do you think the wiring for the valves on the right side may have been damaged slightly? Just odd that those zones controlled by those valves both have low water pressure after the strike. Hence, I was thinking maybe the wiring is not getting the full electricity to the valves to open them up all the way.

Thanks, again!


user1007 06-12-2011 05:58 PM

Have you actually taken an electrical tester to your transformer, controller and wire at the valve ends? If you don't own one, this might be the project to justify getting a tester. You do not need anything fancy but get a good one.

Check the outlet the transformer is plugged into also I guess. Why only one side of the house would be effected is baffling other than that if it is furthest from the transformer and controller you may be losing power through some lightning damaged wire I guess. Weird though.

The power to the solenoid/actuator should just cause it to open and close. You adjust the flow rate manually.

downunder 06-12-2011 06:44 PM

As SD mentioned, the wiring and solenoid simply open and close the valve. I hate to say it, but I'm still thinking toward a cracked supply line between the solenoid/valve and the heads.

My experience with valves is:
Sometimes dirt can wash under the diaphram and prevent it from closing completely resulting in a slow leak (like a worn washer at a faucet).
The diaphram may stick open or closed.
The diaprham is ruptured.
Solenoid can go bad, preventing operation similar to a bad light switch.

Since I understand you have replaced all these parts and are still having a problem I would disregard a valve issue.

One way of checking pressure (with a little trouble, relatively) would be to get a $10 pressure gauge. Get the appropriate connectors for your system and disconnect the weak head and check the pressure there. Do the same at a good head. If they are significantly different (more than one or two psi), go to the valve and do the same thing.

I.E, if you are getting 60 psi at a good head and 45 psi at the other, then check the psi at the out side of the valve to the weak head. If you are getting 60 psi there and 45 at the head, the problem is somewhere in between.

Adapter bushings are readily available for $2 or so. You should be able to put all this together for well under $20, much cheaper than a plumber! Even if you have to cut the line open then repair it, it shouldn't be much trouble.

Get an EZ span to repair the opening. Open it all the way (kind of like a shock absorber) and mark the max extension on your supply line, then close it all the way and mark the min size. That will give you your cut marks then glue and push on to line up with the max marks.

user1007 06-12-2011 07:16 PM

As hinted in my last post, you did not mention that you tested or replaced the low voltage transformer. If the two valves working a closest the transformer you might just be getting lucky with them and enough current is making it to the solenoids. If the others are on the other side of the house from the transformer you may be losing adequate power just over the wire run if the transformer is not kicking out what it should in terms of power.

Otherwise, I agree. The problem has to be in a water line I should think.

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