Question
QUESTION: Contractor installed the Hunter sprinkler system last October.  One of its stations has 14 heads ( 2 with a 360 degree and 12 with 180 degree water coverage).  Now we noticed that the sprinklers are not receiving enough pressure to pop up the sprinkler heads.  The contractor told us that we need to replace a water pressure valve.  When I check the pressure, we have 60 PSI.  Therefore, I do not think we have a water pressure problem.  Are the 14 heads too many for one station or do we need to check the sprinkler valve?   How do we determine a number of sprinkler heads each station can reasonably handle?

ANSWER: Thanks for your question.
Every home has a different water supply, hence the number of sprinklers it can operate will vary.  So it's hard to say what is too many. Do the other zones work all right? If so, how many sprinklers are they running? That's the number of head that should run. Since you have a pressure gauge, test the pressure when the system is off, then test while each zone is running. If you start with 60PSI you shouldn't have much less than 40PSI when the system is running.

The water pressure valve should have nothing to do with too many sprinklers on a zone. If the system was running correctly last fall, it wouldn't have went bad this soon. It was the contractors responsibility to check the water supply and "flow test", if necessary, to ensure 14 sprinklers could run on one zone. It appears they didn't do this.

If you need more help, reply back with a bit more info about your water supply and the results of the zone by zone pressure test.

Matt

---------- FOLLOW-UP ----------

QUESTION: As you suggested, I tested the water pressure by each zone.  The water pressure went down when I ran the system as follows:

Zone 1 with 14 sprinkler heads - 60 PSI to 20 PSI.
Zone 2 with 5 sprinkler heads - 60 PSI to 50 PSI.
Zone 3 with 7 sprinkler heads - 60 PSI to 50 PSI
Zone 4 with 9 sprinkler heads - 60 PSI to 55 PSI

Zones 1 - 3 have regular spray nozzles (each with a 180 degree coverage).  Zone 4 has stream spray nozzles.  

I did one additional test.  While the zone 3 was running, I opened a water faucet at full which is located in front of the house and checked the water pressure.  The water pressure went down to 30 PSI.  I do not understand why the zone 1 went down to 20 PSI.

Answer
Great info.
What you are seeing with the pressure drop for each zone is "friction loss". Friction loss is the "pressure drop" from the friction of the water against the pipe wall. Everything the water flows through has a friction loss, valves, pipe, meter, etc. The more water you try to get through each of these items, the more loss you get. That's the techy stuff.

Zone one has too many heads on it. Your contractor assumed or didn't care to check the water so you have a problem zone. To correct the zone either needs split into 2 zones, which will require another valve and may require a larger controller. Or, reduce the nozzle sizes to lower the water demand. Changing the nozzles is the easiest and cheapest, but you need to be careful. Smaller nozzles also spray less distance, so you will need to pay close attention to you distances. You can get the nozzle sets from any contractor or distributor, they don't cost much if anything.
Try this nozzling. # 5 for the part circles and a #7 for the 360 sprinklers. You can even use #3 or #4 for the corners if you have any. If you can get the pressure up to 35-40 PSI consider it a success. It's not perfect but should work.
If you need any other advice, reply back.

Matt