# Hunter Pressure Gauge Reading Above Target Pressure on (PRS) Regulated Heads



## Inevitable (4 mo ago)

*TLDR:* I have at least a couple, so far, of new Hunter PRS 40 (with check valve) heads reading 45-60 PSI at the head via a new Hunter MP-Gauge Pressure Gauge. What might be causing this and how should I proceed? (I assume PRS 40 heads should never read above 40 PSI and PRS 30 heads should never read above 30 PSI, correct?)

*More detail:* 
I have an existing sprinkler system (probably installed around 2004 when the house was new - I purchased the house in 2021. Runs on city water [I believe it's recycled water from the city that the systems in our subdivision use - separate meter/pipes than that used by house and hose bibs]) that reads about 60-65 PSI at at least a couple of unregulated spray heads I have tested so far. I am replacing these heads with Hunter PRS-30 and PR-40 heads (with check valves) using MP Rotator nozzles.

I ordered everything from Sprinkler Warehouse including a Hunter MP-Gauge (pressure gauge). I have tested the pressure of some of the new PRS 40 heads after installation and sometimes read a pressure above 40 PSI (e.g. 45 PSI). Usually, I'll push down and release the MP Rotator nozzle (perhaps multiple times) and that will cause the gauge's pressure reading to suddenly change and "equalize" to 40 PSI. I assume this is just an inherent weakness of such a gauge. However, on one head last night (after changing nearly all of the heads on an 11 head zone), a new PRS 40 head read ~60 PSI after being installed. Pushing down the MP Rotator head did nothing to "correct" the reading. The MP Rotator seemed to spin faster/spray more water than other heads as I would expect from a pressure of 60 PSI. I swapped the internals with that of another Hunter PRS 40 head and it read 45 PSI. However, once again, I could not get the reading to go down to 40 PSI by pushing down and releasing the MP nozzle.

I assume that a PRS 30 head should never read above 30 PSI and a PRS 40 should never read above 40 PSI, correct? Why would I get a reading from one PRS 40 head of an unwavering 60 PSI? And an unwavering 45 PSI from another PRS 40 head? While I haven't tested EVERY PRS head, others I have tested so far do not seem to have this issue, though I will probably test them all to be sure.

I have only replaced about 25% of the system so far and want to gain as much knowledge as possible on this issue before getting too deep on the replacements and realizing that I have defective heads or something of that nature.

Any ideas on what might be causing this issue and how to proceed?

*Update:* I'm starting to suspect that my water pressure is too high for PRS heads to handle alone and that I may need to do something at the valve to get the results I am seeking. 8 out of 11 heads on the zone (all PRS) are reading more than 2 PSI above the target pressure. I have 5 40-PRS heads and 6 30-PRS heads on the zone. 4 of the 30 PRS heads are more than 5 PSI above the target. One of the 40 PRS heads and one of the 30 PRS heads are more than 20 PSI above the target pressures.


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## Inevitable (4 mo ago)

Inevitable said:


> *Update:* I'm starting to suspect that my water pressure is too high for PRS heads to handle alone and that I may need to do something at the valve to get the results I am seeking. 8 out of 11 heads on the zone (all PRS) are reading more than 2 PSI above the target pressure. I have 5 40-PRS heads and 6 30-PRS heads on the zone. 4 of the 30 PRS heads are more than 5 PSI above the target. One of the 40 PRS heads and one of the 30 PRS heads are more than 20 PSI above the target pressures.


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## g-man (Jun 15, 2017)

Call hunter. I think they regulate from 100psi to 45psi.


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## Inevitable (4 mo ago)

Hunter's product cut sheets for 30 and 40 PRS heads show operational pressures of 15 to 100 PSI. I sent them an e-mail as I was not seeing a phone number for them in my quick search.

I measured 87 PSI on the last head I changed on the zone (it was unregulated). It decreased to 60-70 PSI once replaced with a Hunter PRS 40 head.


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## Inevitable (4 mo ago)

I measured 85 PSI on another head after swapping the PRS 30 with an unregulated head. The PRS 30 head read about 37 PSI when installed. Perhaps, with the PRS head installed, the pressure before the regulator is above 100 PSI on some heads - causing the pressure to be above the target regulated pressure.


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## Green (Dec 24, 2017)

Wow, that's high on several heads. Sounds like it's not a head issue. If you do need further regulation at the valve level, an accu-sync adj is what you want.

Their numbers are:

Customer support: 800-383-4747
Technical: 800-733-2823


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## g-man (Jun 15, 2017)

Ideally you want a Pressure Regulating Valve before all of that (and to the house too). Another option is to see if your valves have a flow regulator, you might be able to lower the flow to lower the pressure, but I would still use a PRV.


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## Inevitable (4 mo ago)

I have what I assume to be the original Irritrol valves (the oldest [unregulated] sprinkler heads appear to be Irritrol as well) - probably from 2004. What would a flow regulator on the valve looks like - and how do they tend to adjust?

I tried manually opening valves on other zones while running the zone in question which seemed to lower the pressure closer to where I expected it to be. With that being said, I might look into being able to run two zones at the same time. I suppose the fastest/easiest/cheapest way would be with a relay setup.


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## Inevitable (4 mo ago)

Can flow control valves be used to control pressure or is using Accu-sync Adj better for some reason?


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