SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

the Watts 919 resembles the Conbraco RPZ, but does not have the testcock on the lower section, so some disassembly will be required when winterizing.

the "older technology" may have a functional advantage when supply pressures are lower (around 50-60 psi)

The combination of a 60psi water supply and an RPZ should mean that you don't NEED pressure reducing anything.

The RPZ itself is going to cause 10 to 15 psi pressure loss. Your valves will likely add another 3 to 5. When you tack on the pressure losses of the meter, the water pipes, and changes in evelvation, you're likely to have around 40 psi of pressure at the heads (a good number).

The only place I would consider any sort of pressure control is if you want to get the 1800 series of Rainbird Popups with the built-in PRS (Pressure Regulating Stem). The PRS is built into the pop-up, and sets the output pressure to 30 psi. And the only reason you would need the PRS is if you want the performance of the nozzles to be the exact same from one location to the next (something that might be needed or desired with large swings of elevation or distance).

I would suggest that you not get pressure reducing valves and instead get valves with flow control and Popus with PRS built into them (neither is a MAJOR cost relative to "basic" features). The flow control will give you some control over the relative pressure IF you should need it, while the PRS will provide the constant nozzle performance.

Stop what you are doing and install the RPZ. Now. Not later.

What Boots said...

Even a manual control valve MUST be protected by some form of Backflow protection. After all, even if you are using a hose spigot (where when the water is off, backflow is impossible since the valve is absolutely shut), there is the possibility of an event that could cause backflow while the valve is open. In that case, the water company could start sucking water from your "testing" equipement back into the water supply.

As for which RPZ, unless your local building athority specifies a particular part number they require for backflow protection, pretty much every RPZ is going to be bomb proof as far as protecting the water supply. So you might as well use the cheapest option.


Otherwise, on the subject of should you use the 009 or the 919, from what I see looking at the devices and reviewing the specification sheets, the 919 seems to be ment for an industrial setting where it gets heavy use and needs frequent maintainence. By contrast, the 009 seems to be ment for less heavy utilization. Otherwise, the level of protection offered by each is the same. Since you're NOT going to be pumping 20gmp 24/7 through this device, I think the 009 will more than suit your needs. (No need to buy a tank to do some off-road driving when an SUV will do the job just fine)

Besides the obvious backflow issue, there is the issue of wasting time. Complete the plumbing, including the RPZ, then worry about the system, because only then do you know what the available flow and pressure will be.