As the name suggests, frost proof faucets are designed to remain usable throughout freezing temperatures. Before them,
it was necessary to turn the water off to your outside faucets and drain the water out before the freezing temperatures arrived.
The key to the design of the frost proof is the length of the faucet. It has a long stem, which shuts the water off well
inside the warmth of the house. Standard sizes are 8", 10", 12" and 14". Shorter sizes exist, but are fairly rare.
The picture above shows the end of faucet in the top picture. The water gets shut off near the end of the faucet, which
is well inside the basement. This frost proof is soldered onto 1/2" copper, which is the normal method of attachment. Most
faucets, however, have a 1/2" male thread on them as well(like the above picture) which can be screwed into a female
connection. This makes it difficult to line up the outside part of the faucet and generally isn't used, except in the case
of a swivel female connection. This allows the female to spin onto a stationary male connection.
The one thing that all residents should be aware of is the need to remove garden hoses from the faucet in freezing weather.
it says "REMOVE HOSE IN FREEZING WEATHER"
The reason for this being so important is that the faucet needs to be able to drain out. The portion of the faucet that
is in the freezing weather needs to empty out. With a hose connected, it keeps this portion full of water, which leads
to freezing and most likely into the faucet spliting, ruining the faucet. Unfortunately, hoses get left on occasionally.
You wouldn't be the first to ruin a frost proof faucet, don't be too hard on yourself.
The other part of the draining necessity comes into play during installation. The faucet must be pitched downward, toward
the outside. If it is pitched backward, toward the house, water will lay in the faucet. This can also cause a split.
In the top picture, you will notice a green cap on the top of the faucet. This is called a vacuum breaker. It is an
anti-siphon device. This piece of the faucet is very important. Many older faucets without them are still in operation, but
all new frost proof faucets are required to have them. They prevent the possible contamination of the potable water system
in the home.
If the outside faucet does not have this long stem design(at least 4" minimum), it is not frost proof.