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Monday, August 28th 2023, 8:15am

Need advice and suggestions on 36 year old system

I know, the simplest answer would be to replace it, but I believe in building things to last and repairing them when necessary. My two main problems are rotor heads that don't rotate as they should, and low pressure / water flow.

I have ordered new RainBird 5000+ rotor heads from the forum sponsor, which I hope will fix the first problem (Original heads were Hunter and have had numerous problems over the years with them failing to rotate).

System is connected to 1" city water meter (share meter with house, not dedicated for irrigation system only). At hose bibb where 1" water service enters house, I can fill a 5 gallon bucket in 15 seconds, so 20 gpm at hose bibb. (Hose bibb is 3/4", so a little reduction for flow likely compared to 1" line going to vacuum breaker). Vacuum breaker is Febco 765 (1"). Pressure gauge that I attach to either VB test cock reads STATIC pressure anywhere from 30 psi to 45 psi, depending on time of day and whether or not everyone else on my street is watering. When I run one of my most demanding zones, WORKING pressure at VB reads 24 psi.

Control valves are Toro 250-06-04 (1", Electric, with flow control). For rotor sprinklers, I have up to 8 heads per zone. Realizing this may be too many, my hope is that I can use the on/off feature of the RainBird 5000+ heads to selectively turn off heads as necessary to improve pressure/flow to those heads that are on. This will be a lot easier than adding more piping and control valves to create more zones with fewer heads per zone.

Realistic expectations? What kind of pressure at the VB should I expect to get decent performance at rotor head that is a good 200' from VB? I am planning on using the smallest nozzles possible to get at least half of the heads on any given zone to throw water at least 25' (and possibly up to 35').

I am located in the Houston area, and exceptionally dry years like this one are the only times I really need the system ... some years I barely need it all if we get our usual rainfall. A fully automated system that required no tinkering would be great, but I can vary run times, run days, and turn individual heads on or off as needed to get thru these droughts.

Thanks in advance for any thoughts, suggestions, and comments!



Posts: 1,505

Location: USA


Monday, August 28th 2023, 2:01pm

I can appreciate your elaborate post. The more info the better.
But your water pressure is ridiculous. Have you considered installing a booster pump?
20 gallons per minute seems to be pretty good though.
I don't have any other suggestions. 2 heads per line might do it.


Tuesday, August 29th 2023, 12:02pm

More info on 36 year old system

I took some pressure readings today. At 11 am, STATIC pressure at vacuum breaker was 47 psi. With the zone running (6 heads) that is furthest from the VB, WORKING pressure at VB was 37 psi, or 10 psi less than STATIC. I had removed the 7th and last head on that zone and installed a pressure gauge there. It read 22 psi (+/-), or 15 psi less than at VB.

Pressure at VB was also measured earlier, and it ranged from 46 psi at 3 am, to 40 psi at 4 am, to 38 psi at 5 am (when I could see some of my neighbors' systems running), to 45 psi at 9 am (when no neighbors seemed to running underground systems). I also measured pressure at hose bibb very near to VB. At 9 am, it read 50 psi, or 5 more than at VB. These pressures seem to match what I have read about how much the pressure will drop when system is running ... any thoughts anyone?

I looked briefly into booster pumps, and didn't have much luck. Can a booster pump be added to a system such as mine which is connected to a city water line? If so, any suggestions on brand(s) or model(s)?

If I am successful in linking a photo, attached should be a photo of my control valves.
Is it normal or typical for all valves to be so close together?
Is there excess pressure loss due to number of fittings so close together?

picture upload site

This post has been edited 2 times, last edit by "mrfixit" (Aug 29th 2023, 2:40pm)



Posts: 1,505

Location: USA


Tuesday, August 29th 2023, 2:57pm

What a strange setup. People can be very creative. It looks like two manifolds. One on top of the other.
I don't think rebuilding the manifolds will much of a difference if any at all.
It looks like a potential nightmare to change a valve though. They look old. See the silver band around the port? They haven't had that for quite some time now. 20+ years I'm thinking.
But that valve is easily rebuilt. The 250 valve does crack on the bottom but with your water pressure, maybe it's not an issue.
Yes you can put a booster pump on city water. I don't have a clue which one to buy. In the thousands of house calls that I've made, I've only seen one booster pump. We have great pressure here. Sometimes too great. It's been measured up to 190 lbs. I have measured as low as 40 but they're just running a few spray heads. Like 6.
Basically you have too much demand for the water pressure that you're working with.
When you measure the pressure, you have to make sure that there isn't air trapped in the gauge. You can get higher false readings if there is. What I do is, I screw the gauge on half way or loose, then turn the water on. It'll leak but that gets the air out. Then tighten it.


Wednesday, August 30th 2023, 5:56am

Thanks mrfixit for your additional insight. Yes, the control valves are old (original to system). If I ever have to work on them, I will rework the manifold(s) then, but will leave as is for now.

One more bit of info, just in case this makes a difference. At the time the system was installed and tested, we had flow / pressure problems right at the start with the most demanding zone(s). The installer suggested increasing the pipe size from the water meter to the vacuum breaker from 1" to 2". I am an architect (retired) and it was not uncommon on some of the projects on which I worked at the time for the MEP engineers to specifiy water service lines larger than the meter size, so I did not think this would be problem. This seemed to help my flow problem at the time, but now I wonder if I sacrificed pressure for greater flow.

I will double check my water pressure readings using your tip about avoiding trapped air.

Feeling lucky after I appeared to have mastered posting pictures, so will try two more. The first one was taken this morning at about 5:30 am, showing the 2" water line going into the 1" vacuum breaker, and 32 psi STATIC pressure at that time. The second picture shows the manifold at the time it was installed, before the main line was increased from 1" to 2".

My new Rain Bird 5000+ heads should arrive in a day or two, and am anxious to see if being able to turn off some of the heads on a given zone will be a solution ...


This post has been edited 1 times, last edit by "mrfixit" (Aug 30th 2023, 11:58pm)



Posts: 1,505

Location: USA


Thursday, August 31st 2023, 12:08am

haha. Sorry but I'm the one who uploaded your pictures. Next time go to, click on "start uploading". Leave it on "don't autodelete", click "upload", then under embedded codes, copy and paste to your post "BBCode full link". The pic will appear in your post.

That trick I mentioned about the pressure gauge, that was for hose bibs. I don't think you'll get any air at the test cock.

And your manifold does have a lot of whooptydo's. Each turn takes away a small amount of pressure. You could easily straighten most of that out. Will it cure your problem? Probably not.


Thursday, August 31st 2023, 11:53am

Mrfixit, thanks for uploading my pictures for me. I could not find any instructions on how to do it, so tried Dropbox.

I got 8 heads replaced this morning. 4 Full Circle and 4 Half Circle. I began by installing just one Full Circle with 3.0 nozzle (2.7 gpm) and left the other lines capped (except for a test gauge at one of the head locations). Then I installed 3 more Full Circle (9 gpm total demand @ 2.26 gpm each). Finally I installed the 4 Half Circle @ 1.5 nozzles (1.12 gpm). Total demand of approximately 13.5 gpm.

Pressure gauges at Vacuum Breaker and at head location were as follows:

VB STATIC: 44 psi
VB with approx. 2.7 gpm demand due to higher pressure at head: 40 psi
Pressure at head gauge: 37 psi

VB STATIC: 45 psi
VB with 9 gpm demand: 38 psi
Pressure at head gauge: 27 psi

VB STATIC: 46 psi
VB with 13.5 gpm demand: 35 psi
Unable to take reading at a head location as all 8 heads were now installed, but pressure at head likely 20 to 21 psi, if same pattern of about 1 psi loss for each gpm. Trying to run all 8 heads at once is too much demand, and puts pressure at head below the 25 psi minimum recommended.

The STATIC readings went up slightly as the early morning demand (from 7:30 am to 9:30 am) in my neighborhood eased.

I am optimistic that if I run 2 Full Circle and 2 Half Circle for a total just under 7 gpm demand that the performance will be acceptable. This first zone is the most demanding (longest run) of my three main large lawn areas zones.

I will try turning off flow at half of the heads this evening and see how good of a spray I get.

This was the spray with just one (1) Full Circle head with a 3.0 nozzle (2.7 gpm) installed. I have not done any experimenting with reducing the spray distance yet. The heads in this zone vary from 30' to 35' apart, and spray was easily going that far.

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This post has been edited 1 times, last edit by "lawnperson" (Aug 31st 2023, 12:58pm)

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