Thread: Anti siphon hose bib question

Hello all,

Is the frost free style hose bib with the plastic cap on top also an anti siphon? I asked a home inspector and he said no. The plumber I talked with said yes.

Thanks for your help.


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The plumber is right

Also, IMO worth noting to clients when the vacuum breakers are broken, replacement kits are available for most types, for example:

Mansfield 400/500 Series Frost Proof Wall Hydrant Vacuum Breaker Replacement Kit - Faucet Repair Parts made by Prier Products, Inc. - Dickson Supply's AccentShopping.Com 1-800-456-5267

Originally Posted by Michael Thomas

Also, IMO worth noting to clients when the vacuum breakers are broken, replacement kits are available for most types, for example:

Mansfield 400/500 Series Frost Proof Wall Hydrant Vacuum Breaker Replacement Kit - Faucet Repair Parts made by Prier Products, Inc. - Dickson Supply's AccentShopping.Com 1-800-456-5267

Thank you for your answers Fred and Michael.

Michael how can you tell if the vacuum break isn't working?

Thank you
mk

Originally Posted by Mike Krueger

Thank you for your answers Fred and Michael.

Michael how can you tell if the vacuum break isn't working?

Thank you
mk

I just observe them for mechanical damage, i.e. the plastic cap is broken/missing.

The big thing with FR hose bibs in my climate (hard freezes) is that they are often installed in locations where the valve at the back of the assembly or the pipe immediately behind it is still subject to freezing and/or the assembly is pitched up toward the exterior, not down so it can drain once the valve is closed and the hose disconnected:

You can easily test a vacuum breaker by hooking up a hose to the sillcock, and raise the hose over the height of the sillcock and turn the water on let it run for a few seconds then turn the sillcock off.the water in the hose will cause the breaker to open and leak out some water preventing it from back siphoning. While the water is running the vacuum breaker should not be leaking.

Good info

Thank you

Thanks, Ron. Added to my list of things to check when the water is on and a hose is attached.

Always a pleasure to help educate others in the way of plumbing. *grins*

I wonder if the inspector thought the question was anti-backflow? Which leads to my question--these are not anti-backflow are they?

Originally Posted by Kary Krismer

I wonder if the inspector thought the question was anti-backflow? Which leads to my question--these are not anti-backflow are they?

Hello,

In my understanding they are one in the same .

mk

OK for all you home inspectors out there here is a list of anti backflow prevention:

1. Air Gap (yes this is a form of anti-backflow Notice how the bath tub spouts are no longer built into the tubs)
2. vacuum breaker Mostly found on sillcocks, or any faucet that you can attach a hose to. These can not have a shut off after the device.
3. Pressure Vacuum breaker. These are used on lawn sprinklers where they are allowed. Its the only vacuum breaker you can have a shut off device after it.
4. Single Check Not to often seen any more but mostly used on recirculation lines to keep the water flowing in one direction.
5. Duel check - these are used where a vacuum breaker does not provide enough protection against the reversal of flow, you will see these more on coffee makers and soda dispenser machines that have carbonation and are usually stainless steel.
6. Double Check Valves These are one step away from an RPZ They are field testable and are to be tested and certified yearly with a report that stays with the device and a report given to the water department. These are common on fire sprinkler systems and at the water meters.
7. RPZ (Reduced Pressure Zone valve) These are the elite in backflow prevention. They have two check valves just like the Double check but between the two checks is the Reduced Pressure Zone which there is a piston being held shut with the line pressure before the first check valve, there is a pressure drop due to the water having to open the spring loaded check valve and if for any reason the pressure = or becomes greater then the supply pressure the piston will open and dump out the contaminated water. These valves need to be tested and certified yearly as well. These are being required by more municipals to be installed on lawn sprinkler systems, fire systems that can receive chemicals, boilers that have chemicals, or any other high risk cross contamination.

I hope this helps you all a little.

Originally Posted by Mike Krueger

Hello,

In my understanding they are one in the same .

mk

It's designed to prevent back-flow, but is it a check valve? I thought they were just devices that create an air gap when the pressure is released, thereby preventing water from siphoning back into the system.

What I'm getting at is this. If you had a pool that was 20' above the valve, would it prevent backflow if the system lost pressure. I know it would if the pool was below the level of the faucet.

Originally Posted by Kary Krismer

It's designed to prevent back-flow, but is it a check valve? I thought they were just devices that create an air gap when the pressure is released, thereby preventing water from siphoning back into the system.

What I'm getting at is this. If you had a pool that was 20' above the valve, would it prevent backflow if the system lost pressure. I know it would if the pool was below the level of the faucet.

Its a vacuum "breaker" So if there was a vacuum or lets call it a negative pressure on the supply side of the vacuum breaker it will open and prevent the water from siphoning back into the supply.

Thats why I said one way to test the vacuum breaker is hook up a hose to the sillcock and turn the water on, hold the hose higher than the sillcock and turn the water off. If it works water should leak out from the vacuum breaker.

Now a vacuum breaker is not 100% in preventing all the water from getting back into the supply. That is why if the supply has different degree of hazards will require a better backflow prevention device.

"Vacuum Breaker": A device which prevents the creation of a vacuum by admitting air at atmospheric pressure, used to prevent back siphonage.

"Vacuum Breaker, Hose Type (HVB)": A back siphonage prevention device designed for hose connections which are not under continuous pressure, and meeting the requirements of ANSI/ASSE 1011.