Yes, the anti-siphon device is a kind of valve designed to admit air and allow the long segment of tubing in the wall outside of the deeply resessed valve to drain its retained water.
The deep resessed valve is within the warm house. When the valve is closed, the standing water is kept above freezing by being indoors. The water beyond the valve drains, so even if that part of the faucet gets below freezing, there’s no water to freeze and cause expansion damage.
What climate are we talking about here? Out here in USDA zone 6, we don’t need anything more than a frost-proof bib like the one pictured (and remembering to take the hoses off so the faucets drain).
What’s the need for an anti-siphon device? I just shut off the water to the garden taps, open the taps, and that’s all I do until spring. The water between the shut-off in the house and the open tap just drains naturally.
The main use of the anti siphon isn’t about draining the line. It’s to prevent a reduction in household water pressure from siphoning water from an attached hose back into the household water supply.
You’re right that the frostproof valve arrangement drains pretty well by itself.
Yes, I would not expect plumbers to use them, and I am sure paying a pro would get you a higher quality result. I also would not be doing any DIY work that was going to be buried or enclosed in a wall, so I don’t really disagree with most of that, and yet I’m still comfortable using it for certain things. My plumbing is all accessible overhead in my basement. OP’s is in the crawlspace.
But of course people can judge for themselves the risk/reward balance.
I paid my plumber to fix something I was not able to repair, and I asked him to check everything else I had done and replace anything that was a problem. He had no problem with the Shark Bites, and, as I said, just said they were too expensive to use on a big job. I’m sure he would never use them because he has a crimper, which is a very good permanent connection that is pennies per use.
My new house (15yo) has pex. The outdoor faucets (back yard and garage) are essentially those no-freeze types, since the temps can dip below 0°F. They are about a foot long, sticking through the wall. The stem for the faucet is about a foot long, so the part that is exposed to the outdor contains no water when it is shut off. (I still have to disconnect any garden hose). All the plumbing connections to those faucets are on the heated side of the house wall. I see that one of these is called the “Shark Bite” on plumbing sites or Home Depot. Another brand is Acqua-Dynamics.
The only complaint I have is that I’ve broken part of the plastic handle, and the screw holding it has rusted solid. The access to the indoor connection is in an awkward place.
I find it incredible there is noeasily accessible full house shutoff valve. Every house needs one. What if a pipe breaks? (As a kid, I stood on a pipe in our basement and broke it - there was a pretty good flood before I found the cutoff valve. Plumber said I was lucky, a foot over I would have broken it on the other side of that valve.)
It sounds like that’s the cutoff from the water supply, which every house should also have. Typically, though, there is also a readily accessible cutoff valve that is at the house itself. Every house I’ve lived in as an adult has had one. In my current house, it’s in the basement. It’s within a couple of feet of where the water supply pipe enters the house. I need a tool to turn off the water at the street. The main valve inside the house is a modern 1/4 turn lever.
What would be the purpose of having a valve to shut the water off to the house, when the valve at the street is for turning the water off to the house?
The curb stop (the outside shutoff valve) is often reserved for use by the city or utility company only, to the extent that it requires a non-standard tool to operate. (The ones I’m aware of use a pentagonal head wrench.)
But in those jurisdictions, I think an indoor shutoff is also required by code.
FWIW, I appreciate having an indoor shutoff valve. It’s a lot more accessible in emergency situations like a high-flow plumbing leak.
In many cases the valve at the street requires special tools to shut off and is meant for use by the water company only (at least in places I’ve lived).
No curbs here. The county water department showed me where it was and how to turn it off. The tool is a long pole with a T-handle, and a U-shaped bit at the end. Like this. After I bought a tool, I discovered one that came with the house, in the shed.
“Curb stop” is just the standard plumber’s name for the valve. It doesn’t require the literal presence of a curb.
The design varies from jurisdiction to jurisdiction, of course. Some are just u-slot sockets that can turn the tab on the valve. Assuming the valve itself is accessible year-round, it might be good enough. (But it would suck hard to have to dig the valve out from under 2 feet of snow while my basement is flooding from a failed pipe joint.)
Others are indeed an intentionally obscure 5-lobe nut design, clearly meant to be used by someone other than the occupant. Anyone can buy the appropriate wrench from a hardware store or online, but it’s pretty unlikely they’ll have one in advance of when they need one (unless it’s literally the only cutoff, but hopefully the house will already come with one in that case).
My own curb stop is by the curb in our suburban neighborhood, so gets comprehensively buried by snowplows*, so it’s not a hypothetical concern in my case.
*When this happens, I might wish it were only two feet.
The valve at the street is called a stop and waste, or curb stop. It shuts off the water to the house and drains the line to the house at the same time. I know what they look like in Denver, but not sure what you have. This is a tool for it.
‘Hose bib/Sill cock’ same thing but reginal differences on what they are called. The answer is of course, “It depends”. Just insulating a pipe will in the long run make no difference. It needs a heat source like heat tape/cable. It of course “Depends”. If it’s gonna stay below freezing for weeks, and no water is run through the pipe, there is no difference.
Back in the '70’s my family owned a mobile home park. MH’s are notorious for having frozen supply and drain lines. We put heat tape and then insulated many of them. Some did not want the expense and just dripped the water. Well, your supply line is good, but the slowly dripping water froze up in your drain line.
Just had a septic system replaced at my house. Contractor put heat cable below the line out of the tank. Fine with me but I insisted on an on/off switch. No point in running it in the summer.
For the sill cock on the outside of my house, I put a shut off on the pipe in a wall that always has heat. Shut that, and then drain that sill cock. Done. But we do get -20f every winter, had to be sure. When both my wife are gone for more than a few days, we shut the well pump off. Easy to do for us, and best to be sure.
The county water department showed me where it was and how to turn it off. The tool is a long pole with a T-handle, and a U-shaped bit at the end.