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rvsuper
07-25-2002, 09:31 AM
I was repairing a system today (a few heads got worn out). So I go to the timer to test the new ones. Well, I noticed that the system had an AVB insteds of a PVB. The system I believe has 6 stations. Last time I checked, aren't AVB's supposed to be after EVERY valve? I have never used these things before, so that is why I am wondering??????????

HBFOXJr
07-25-2002, 09:36 AM
You are correct, OR an RPA or PVB at the point of connection.

rvsuper
07-25-2002, 09:39 AM
I don't know who installed this system (it wasn't me) but do you think I should do something about them installing these?

HBFOXJr
07-25-2002, 05:38 PM
Yes, it is good to upgrade to code. Makes $$$ and good relations. If elevation is not a problem just install 1 PVB before all else. Yes, you can blow thru them to winterize.

If elevation is a problem, use an RPA but you must know if you can support the higher pressure loss the create before you do a deal. Sometimes under marginal conditions booster pumps or other changes might have to be made. In that case it may be more economical and practical to put an AVB after each valve.

Ground Master
07-25-2002, 07:02 PM
You could also install a master valve before the AVB, but my guess is the AVB is ancient, so go with the proper backflow device.