PRV or something else?

[moorem]

Hi All. I am starting to design a rainbird irrigation system for my 1/2 acre lot. I'm on city water. I have a 3/4 inch water meter, 50 psi coming out of my garden hose spigot, but what I think is low flow. It takes 40 seconds to fill a 5 gallon container, which is about half what rainbird reccomends. I always thought my pressure was fine until now. Right after my main water shutoff valve is what I assume is my pressure reducing valve. I screwed the knob on it all the way in and there was a very slight increase in pressure. It took about 37 seconds to fill the same 5 gallon container after this adjustment. Is there anything else I can do to increase pressure? Thanks!

[LazyPup]

I would be curious to know what the model number is on your sprinkler heads. I just checked the catalog and all the Rainbird sprinkler heads recommended for residential applications are rated to operate at a pressure between 15 and 70psi which is within the range of typical domestic water supplies.

Residential water supplies must be regulated to insure the pressure can not go above 80psi.

The largest residential water demand listed in the International Residential Plumbing Code is a bathtub/shower, which is rated at 4gal/min. at a minimum pressure of 8psi.

Residential water supplies are simply not designed to provide a flow greater than that.

[moorem]

Lazy, thanks. I don't have sprinkler heads yet. I'm just in the design stage. Rainbird recommended 17 gpm which seemed crazy to me. I have just under half that and it seems more than ample to me. The rainbird tech I spoke with said that my pressure was only high enough to operate 2 sprinkler heads per zone. I am starting to think that the problem is with the technician I spoke to, not my water pressure. I will call back and ask to speak with someone else.

[LazyPup]

Typical daily water usage for a family of four is about 200gal.

at 17gal/min the irrigation would use as much water in 11 minutes as the entire house does in a day. I would hate to see that water bill.

[SSN596]

With 3/4" pipe and 50PSI you could use a number like 12 gallons per minute. For typical pop-up sprinklers, a full circle is about 3 GPM, half circle 1.5 GPM, quarter circle about 0.75 GPM. SO you could be anywhere between 4 and 16 heads per zone, depending on the mix.


The reason you get low numbers on your flow test is that hose bibs are definitley NOT full-flow valves, AND that bibb may be supplied by a lengthy run of ½" pipe within the house.