View Full Version : Frost-Free question

08-07-2012, 02:42 PM
I recently replaced the washer on a frost-free hose bibb. It is the anti-siphon style of valve. The new washer cured the drip from the spout, but when I turned the water on I got a stream of water from a small hoe in the shaft which connects the handle to the washer. This shaft appears to be hollow. I've replaced washers on these valves in the past and never had this experience. What's causing this???

08-07-2012, 10:27 PM
I expect the only people that could answer your question with any certainty would be the people manning the tech support phone lines at the company that made that frost free faucet.

I'd look for a manufacturer's name on that faucet and Google that name to find their web site, and ask their tech support people what water leakage out of that hole is meant to indicate.

Did you see any O-rings on that stem when you had it out?

Most people aren't aware of it, but O-rings don't have to wear out to leak. O-rings have something called a "compression set" to them. When the O-ring is new, it's cross sectional shape is round, and it exerts sufficient pressure against the bore that it's in to prevent water leakage past the O-ring.

However, rubbers are actually extremely viscous fluids, not solids, and as a result of being kept in compression for many years, the O-ring will gradually change it's cross sectional shape to conform to the space it's confined to. If the mechanism that the O-ring is installed in is used and the O-ring called on to do it's job, that O-ring will leak. That's because the change in the cross sectional shape of the O-ring results in it's no longer being able to exert the same outward force against the bore to prevent water leakage past the O-ring.

So, if you don't bother changing O-rings in seldom used faucets because you figure there's little wear on the O-ring, you're fooling yourself. An O-ring will go out of shape as long as it's under compression, whether the faucet is being used or not. And, once it's distorted sufficiently that it doesn't exert sufficient outward force to seal of water flow past it, the next time you use that faucet, the O-ring will leak. And that's true even if you only use a faucet once a year, for example.

What I'm thinking is that you may have changed the washer in this frost proof faucet many times before, but if you've never changed the O-ring(s) in it, it may be water leakage past some O-rings that's causing water to drip out that hole.

Different rubbers used to make O-rings have different compression set resistance ratings, and a higher compression set resistance rating means the O-ring will change it's cross sectional shape under compression more slowly for a longer life.

08-08-2012, 06:50 AM
Nestork, thanx for your <only> reply. Don't recall any O rings on the shaft. This faucet is original to the house, almost 20 yrs old. Couldn't make out the brand name-there were raised letters USA cast on one side of the valve body and three other letters beginning with "A" on the other. Not a brand I'm familiar with and maybe out of business? One thing I forgot to mention, there is another identical frost-free valve on the other side to the house which had the same leak out the little hole, and I did nothing to that valve. I'm wondering if it is somehow related to the ant-siphon mechanism, equalizing air pressure or some such. I did this work just before the woman left town for vacation so I haven't been able to go back and check the situation. I was hoping to have a definite solution by the time she returns...

08-08-2012, 09:37 AM
Sorry, but I just don't know enough about antisiphon faucets (let alone antisiphon frost free faucets) to know what that hole is for and what water leaking out of it means.

What I would do if I were you would be to take a photo of it with a digital camera, print that picture off and take it down to your local plumbing inspector's office at city hall. It's their job to check that antisiphon devices are installed correctly and work properly. They would almost certainly know what that hole is for (as every antisiphon faucet likely has something similar) and what water leakage out that hole indicates.

But, if the faucet doesn't leak when it's shut off, maybe it's not a real concern. If the only time water leaks out of that hole is when you're running water out that faucet, then the amount of water wasted is very small.