Backflow Preventer Problem

Mike T., Swampeast MO

Went to start up my irrigation system and the $*(# RPZ double backflow is constantly venting water--it's vented water before, but in "spurts" that were caused by air pockets. This time, it's a constant flow.

Was checked out last year (as required) and one of the pistons (or whatever they're called) had to be replaced--cost nearly as much as the unit itself. Unit only about 5 years old (Watts). Inside my garage, so I "winterize" by isolatation before having the meter shut down for the winter.

1) Do the pistons get stuck? Remove covers and reseat?

2) Any recommendations on more reliable backflow preventers?

3) Any recommendations for ones that don't introduce a significantly larger pressure drop than rated?

Thanks!

p.s. My lawn irrigation is redundant when it comes to backflow. When I started building, vacuum breakers were the only thing required. All zone valves are installed at least 18" above elevation of served areas--all lawn/garden hydrants have their own vacuum breakers. When I finished three months later and had system inspected and new meter installed, rules had changed and the RPZ device was required. 1¼" backflow on 1" meter w/1¼" service entrance. According to specs it was supposed to handle my flow at typical pressure, but it has always seemed to introduce significantly greater resistance to flow than stated.

clammy

backflow

Hello mike i occasionly do lawn springler water line install for friends who do it for a living .Usally i cut them in before any pressure reducing valve on the water main ,i know there are 2 models of back flow preventers made by watts a cheaper one and then the 1 in and out unit which is about 116.bucks alot more then the other unit i,ll try to get you a model # i have installed at least 7 or 8 in the past 2 years and have had no call back orweeping promblems .I believe there's 2 screws that hold the plunger **** together and that the cuts are not as expensive as the whole unit .Is there alot of sediment in your water and are you city or well water does your unithave isolation valves on both sides of it if not it may be the cheaper model how about yourwater pressure and i believe on some appacation you may need a check vale before your back flow ,i,ll get back to you with a model # peace and have a great day

Mike T., Swampeast MO

Thanks Clammy.

It's a Watts 909QT, 1¼".

City water, no system PRV but there are individual PRVs on soaker hose zones. Daytime pressure in the 55-60 psi range, 0-dark-30 pressure in the 60-70 psi range. Original isolation valves and strainer. Little sediment (strainer has very little in it when I clean each year) and all piping is quite new copper.

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Took the entire thing apart (clean inside--nothing obviously wrong), put it back together and now it's working fine. Go figure...

gerry gill

nothing to figure.

it takes very little, and i mean very little debris to make a backflow device fail to seat..a spec the size of a pencil dot will cause problems..the 909 is the best device ever made..its the caddillac of backflows..now the 009, well,,we wont go there..bottom line, yup, cleaning fixes the problem 90% of the time..they really should be rebuilt about every five years too..

Dave Yates (PAH)

if you want to stop

the intermittent spritzing, install a soft seated check valve ahead of the RPZ. Your lawn sprinkler heads can cause enough downstream pressure fluctuations to create that problem.

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