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Todd F

Starting Member


Saturday, February 18th 2017, 1:03pm

Is it against code to connect a timer to a hose bib?

I have connected 1 orbit 4 Zone Timer to my hose bib so that the timer is of course downstream. 

Plumbing code states as follows... "A shutoff valve should never be placed downstream of any AVB, as this would result in continuous pressure on the AVB"

I have also come to learn that hose bibs (shockingly) are not designed is be left turned on/open and therefore exposed to continuous pressure for more than 12 hours.

That said I have the following questions:

1) Is the anti-siphon valve in my woodford frost proof hose bib/sillcock an AVB which then automatically creates a code violation if I connect my timer beneath it?

2) Is there still technically "continuous pressure" in my hose bib even when the feed to the hose bib is turned off from my garage because my timer is screwed on beneath the hose bib and water can't escape?

3) Since I only water between 5am- 7am - - if I were to manually (or find an automated way to) turn off the ball valve in my garage that feeds the hose bib from 8am - 9pm (13 hours) - - am I technically in compliance because water is only flowing to my hose bib for 11 continuous hours?

4) What if I ALSO connected screw-on vacuum breakers underneath each of the 4 zones of my timer? Wouldn't that be effectively providing DOUBLE backflow protection from below AND above from what's built into the hose bib?

Bottom Line - Am I simply "SOL" when it comes to connecting a timer to a hose bib?

Thanks in advance for your advice.



Supreme Member

Posts: 482

Location: Houston, Texas


Saturday, February 18th 2017, 4:44pm

great question

You know I am a Sprinkler Guy, a Backflow Guy, and a CSI in Texas...
The AVB is not a Testable Assembly with a set of Differential Pressure Gauges, but in can be inspected for proper installation and operation.

You are correct that the AVB is not to have more than 12 hours of Constant Pressure on it in a 24 hour period and it must be installed 6" above all down stream water connections or sprinkler heads or piping.

This really becomes an issue when you have a home inspection or change owners of the property as it will trigger an inspection. I think that if you wanted to be safe, you could install a double check valve or a pressure vacuum breaker depending on local codes, after the hose bib and before your timer so that you won't get a rush of water hitting your backflow prefenter everytime the sprinkler kicks on.

You could go with a fairly small one keeping in mind your supply is probably 1/2" or 3/4". You volume would be relatively small, but you will want to keep your friction losses in mind when planning your mainline size.

These are my thoughts.

:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

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