New anti-siphon vacuum breaker on hose spigot

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Old 07-21-08, 12:23 PM
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New anti-siphon vacuum breaker on hose spigot

I recently replaced my outside hose spigot and vacuum breaker. The new vacuum breaker (Watts Series 8) performs differently than my old one, and I was wondering if someone here could tell me whether or not this is a problem.

With the old unit, if I built up pressure in a garden hose (used a sprayer attachment and kept it closed), and then shut off the spigot, the vacuum breaker would release the pressure in the garden hose, spraying it through the relief holes.

With the new unit, if i build up pressure in a garden hose and then shut off the spigot, the vacuum breaker does not release the pressure and the hose remains pressurized. Thinking this may be a problem, I tried unscrewing the vacuum breaker on the side of the spigot. Water flowed backward through the vacuum breaker, out the unthreaded connection. Since water flowed backwards from the pressurized hose to the unscrewed spigot side and not out the relief holes, it seems to me that the vacuum breaker isn't doing its job.

Can someone tell me 1) when turning the water off, is the vacuum breaker supposed to immediately relieve pressure as with my old breaker, or if it's supposed to keep pressure as with the new one, and 2) was unscrewing the pressurized vacuum breaker a valid experiment to show that the vacuum breaker does not do its job?

Thanks for any help with this.
 
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Old 07-22-08, 06:28 AM
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Do you know exactly which model the old Vac breaker was as compared to the new one.
Look at this page and read the slight differences.

http://www.watts.com/pdf/es-8.pdf

Why did you not just install a sillcock with a vac breaker built into it?
 
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Old 07-22-08, 11:30 AM
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The old vacuum breaker came with the house, and wasn't a Watts brand. The new one is a Watts model 8 (just 8, not 8A etc).

To be honest, I didn't know that a built-in vacuum breaker was an option. We had a leak, the plumber soldered a new valve on, and I purchased this vacuum breaker. Reading my description of what's happening, does it sound like the new vacuum breaker is working properly?
 
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Old 07-22-08, 03:04 PM
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It is working properly.



8A - Furnished with exclusive “Non-Removable” feature and
standardly equipped to allow sill **** to be drained.
Note: Device should only be installed on approved sill cocks
containing at least four full threads. Non-removable
once installed.
8 - Similar to the 8A except it is furnished without the
“Non-Removable” or draining feature. Secured with Allen[FONT=verdana,geneva,lucida,'lucida grande',arial,helvetica,sans-serif] [/FONT]head set screw.

8B - Furnished with break-away set screw to provide a
tamper-resistant installation. Standardly equipped to allow
sill **** to be drained.
NF8 - Especially made for wall and yard hydrants. Permits
manual draining for freezing conditions.
8P - Furnished with exclusive patented “Non-Removable”
feature. Standardly equipped to allow sill **** to be drained.
Constructed of durable, corrosion-resistant, reinforced
thermoplastic. Tamper-proof feature.
8AC, 8C, 8BC or NF8C - Same as above but furnished
with chrome finish.
8FR - With freeze relief feature. Protects the 8FR from freeze damage.
 
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Old 07-22-08, 04:06 PM
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Originally Posted by plumbingods View Post
It is working properly.
Okay, thanks. I'm just wondering, if water backflowed through the vacuum breaker when it was unscrewed at the valve, isn't this the exact condition that it's made to prevent? What am i missing here?
 
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Old 07-22-08, 04:24 PM
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Here is my understanding of how the vacuum breaker works

When there is pressure in the line the vac breaker acts like a check valve and closes so no water escapes. When there is a negative pressure on the line, the vac breaker opens to introduce air and prevent a vacuum from occurring so you do not contaminate the potable water source.

Your old one may have had a weaker spring in it, that is why it would drain out after the water was shut off.
 
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Old 07-23-08, 12:04 PM
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For what it's worth, in the Watt's Regulator pdf, under specifications it says.... 'this device not to be used where a backpressure condition may develop'.

I would think that pressure building in the hose when it's valved shut may not be a good thing.
 
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Old 07-24-08, 11:16 AM
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Thanks for that explanation, plumbingods. I was thinking that the vent holes were to let out backpressure, instead of let in air, in a vacuum situation.

sjc1701, I previously read that also, but I took it to mean that someone shouldn't cause the outlet pressure to exceed inlet line pressure such as via an external pump. I can't imagine that they are saying the device is incompatible with standard garden sprayers.
 
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