No pressure on pop-up lawn sprinklers after replacing them

Hello Forum,

Please note: I am an amateur when it comes to irrigation.

I have a small lawn (around 800 square feet) with an automatic two-zone sprinkler system that got probably installed around 1985. I own the property since eight years and decided today to replace the pop-up sprinklers because they sometime did not pop up correctly or sometimes did not go down correctly. For now I only replaced one zone with four sprinklers and put "Rainbird Sure-Pop 600" in.

Replacing the sprinklers was easy, however, I now have hardly any pressure on that zone (the other zone with the old sprinklers still works ok). After hours of trying this and that top no avail (very frustrating) I finally opened the little screw that is on top of the valve that is in the underground box. I believe that it is some kind of bleed valve (whatever that is ...) - and when I removed this little plastic screw not only came water out of the valve (spraying through the hole for the plastic screw up for about 1 foot) but I also suddenly had all the pressure of the world on the sprinklers. When I then put the plastic screw back on the pressure on the sprinklers got a little less but was still ok. When I then switched the whole system of and on again I had again no pressure on the sprinklers ... like before ... until I removed the plastic screw from the valve again ... and so on.

Can anybody explain what is happening here and what I might have to do to have the system work normally again?

Thanks for your replies!

Greetings - desertman

 

It sounds like for some reason the solenoid plunger in the valve is not relieving the pressure on the diaphram that acts as the main valve the same way as the manual pressure bleed off screw is doing successfully. Maybe this one old solenoid valve is partially plugged internally. Try new pop up heads on the other zone. Some solenoid valves have flow control adjustments on them in addition to the manual "bleed" valve; if so, is it open all the way for full flow? I guess the new heads are rated for a much higher gallons per hour delivery than the old heads. If the heads stuck in the up position before and that was not fixable by cleaning them, then replacing them was correct, but now with the new heads and the old valve, if the valve in manual operation is able to give you full flow, then the valve and piping are probably sized OK. Did you measure the voltage going to the solenoid valve at its coil? Should be 24 volts AC on any normal setup

 

Hi again,

Attached two photos from the valve, one with the plastic screw, one without (and water coming out).

Would be great if you could give me tips what is going on here. Thanks.

Greetings - desertman

 

The valves look like they're laying in mud and should be laying on something like gravel to allow water to drain down, but keep the area cleaner than it is to prevent any mud from entering when you open anything down there. The electrical connections to the cable could be a lot better than they are by using ready made grase caps or by making your own (nah, buy some). Looks like your valves are Richdel Lawn Genie's by seeing the stainless steel half rings and screws holding the valve together. You might try shutting off the main water supply to this sprinker manifold and after cleaning off the valves exteriors, take them apart, clean them, look for things that stick, etc. there's not much in there. Valves like that are cheap, and if can find the same ones, you may be able to use just the upper part if the lower half looks in good condition. Looks like they are glued in, so if you can reuse the lower plastic casting, it will be an easy job. And yes, I see the water shooting out. Normally, you just turn that plastic screw out just a little to let the pressure out instead of removing the entire plastic screw. The plastic screw is hollow and has a little hole in its side to let some water out, which allows to valve to open.

 

you can try redoing the wire connections but most likely you will need to replace the solenoid wich is the part the wires are connected to and that should fix the problem.

 

last time I looked, the solenoids cost about the same as the whole Lawn Genie valve they sell in the Ace Hardware store near me.

 

personly, since I'm in irrigation I would just replace the valve with a better quality valve such as rain bird or hunter. in this case it looks to be an easy replacement, just cut the downstream line about 2" from the adaptor and 8" away the unthread the valve, thread the new valve on and use a slide repair coupling to reattach the piping.

 

At least since I took of the upper part of the valve and reattached it I'm sure that the membrane is gone. My local Ace Hardware store does not carry Lawn Genie/Torro/Richdel but Rain Bird and Orbit - repairing seems not an easy option. I also think that the solenoid is gone; it is literally falling apart. Funny that this all happened after I replaced the pop-up sprinklers ...

However, I do not quite understand your instructions. Could you please try to explain this to me once again in different words? What do I need to buy to do it? What exactly do you mean by "cut the downstream line about 2" from the adaptor and 8" away the unthread the valve"? Thanks!

Greetings - desertman

 

sorry my instructions were a little hard to understand. first the parts and tools- 1 pvc saw, pvc cement and primer, 1 valve, 1 expandable repair coupling. 1 male adaptor, plumbers thread tape. second, removing the old valve- make two cuts in the pipe on the out flow side of the valve, this will be the side of the valve that the solenoid is on. the cuts should be about 2" and 6" from the valve. after removing this peice of pipe you can unthread the valve from the main line. third, installing the new valve- wrap the threads of the existing male adaptor with thread tape, thread the new valve into place then using the repair coupling and a new male adaptor repair the pipe and thread the new adaptor into the valve. and last reconnect the wires to the new solenoid. I probably should os said that all this should be done with the water shut off at the source. here is a photo of a repair coupling that may help.

 

what about the glue? you left out the glue.

 

glue = pipe cement and primer

 

Pop up Sprinkler heads that operate at a lower pressure are subjective. Low pressure as compaired to what? There are no heads available to meet .ALL low pressure conditions you need to know what nozzels you have installed now and if there are nozzels available for your heads with a lower flow rate. Your problem is flow and not pressure.