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

After you repair it? or Reinstall it it should be tested by a Licensed Backflow inspector to insure proper function. Basically you are checking to make sure the air inlet valve opens at 1.0 PSI or greater and that The Check Valve holds at 1 PSI or greater.

With out Differential Pressure Gauges you can not inspect the backflow device.

Good Luck
Warming up in Houston

After a hard freeze Wilkins Vacuum Breaker began to leak. I unscrewed the top of the cap, then tried to remove plastic bonnet. I finally was able to use a strap wretch to remove the bonnet turning counter clockwise, although there is NO threading on the bonnet cap or brass main body. It just takes a little elbow grease, then you will be able to insert the rebuild kit.

Ditto what wetboots said....

I think the bonnet on a 420 just unscrews. Of course, if you cracked off the top half by letting water freeze in it, the remainder will be difficult to remove. Save yourself some grief, and just replace the whole thing, and set up the plumbing so that you can drain all the above-ground pipe and valves.

Step #1: Turn off you Caps Lock. Doing that usually denotes shouting, and it's very difficult to read.

Step #2: If you don't know enough about a PVB to know how to open it up (not that I do, as I've never messed with a PVB), perhaps you shouldn't be trying. I know that's not really any help, but my real point is perhaps it would be easier to just replace the entire unit. After all, if it's been damaged by a freeze, it might be more than just the guts that now have a problem, the entire unit could be cracked or bent such that replacing "guts" might not fix the problem.

MY NAME IS JOHN CARR, I RESIDE IN LAS VEGAS, NV. A MONTH AGO, (JAN) IT WAS VERY COLD FOR ABOUT A WEEK OR SO (BELOW FREEZING AT TIMES). ANY WAY, DUE TO THE EXTREME COLD, WE DECIDED TO TURN OUR SPRINKLER SYSTEM OFF UNTIL IT WARMS UP SOME (FEB). WE CAME HOME ONE NIGHT, AND UPON ENTERING THE GARAGE. WE NOTICED THE PRESSURE VACUUM BREAKER (JUST OUTSIDE OF GARAGE) WAS SPEWING WATER. SO I TURNED IT OFF AT BOTH VALVES, AND IT STOPPED. WELL, NOW IT'S FEB, IN THE 70'S, AND I NEED TO REPLACE (I GUEST) THE GUTS INSIDE TO PREVENT IT FROM LEAKING. THE PROBLEM I'M HAVING IS, I CAN'T REMOVE THE PIECE INSIDE TO TAKE IT OUT. IT STATES ON TOP "DO NOT USE A SCREW DRIVER TO REMOVE." I'VE TRIED TAPPING ON THE PLASTIC, HOPING TO LOOSEN IT, NO RESULTS; I'VE TRIED TAPPING UNDERNEATH WITH SCREW DRIVER, AND HAMMER, NO RESULTS; I'VE EVEN TRIED USING A LARGE SET OF PLIERS TO EITHER PULL, OR ATTEMPT TO TURN, WITH NEGATIVE RESULTS. WITHOUT DAMAGING THE BONNET OR POPPET ASSEMBLY HOW DO I REMOVE IT FROM THE PRESSURE VACUUM BREAKER?
PLEASE HELP ASAP,
JOHN