Anti-Siphon Spigots Installation – Home Plumbing Tips

For homeowners who live in areas of cold weather, there's no better plumbing component than anti-siphon spigots. They cost a little bit more, but you'll never have to worry about the cold weather damaging an outside spigot again.

Water can get trapped inside the spigot and sillock. When the temperature gets down to around 20F/-7C, this water will freeze and expand. You're probably wondering why this doesn't happen when the temperature reaches 32F/0C. the water can withstand lower temperatures because of the heat from the house.

This frozen water will possibly cause the same problems that frozen pipes under the house will.

The problem is that ice occupies more space than water does. Most of us have done this experiment in school. Fill a cup with water and then place it in the freezer. When it's frozen, the ice will extend up above the rim of the cup. In this example, the top is open, so there is no damage to the cup. This is because the extra volume has somewhere to go. In an enclosed environment, something has to give to create more space.

It may not be as bad if it were only a chunk of ice we were dealing with. As more air and water enter a space that is already filled, you can imagine the pressure that puts on the spigot and sillock. Even the strongest of materials can split and break. The fact that the cold air has made them brittle does not help either. Plastic and rubber do not stand a chance under these conditions.

After the winter has passed, and all the ice melts, you still have a cracked spigot. You'll notice the problem the first time you turn it on, if it's not leaking already.

Anti-siphon spigots are designed specifically for these conditions. They have a built in mechanism to compensate for this problem. This mechanism is intended to combat the effects of frozen water expansion.

The way it's designed will prevent it from splitting and cracking like a standard spigot.

First, the valve that stops the water flow is located further back inside the sillock, which would make it warmer because it's in the house. The warmer temperatures make it more difficult for the water in that area to freeze. It's also designed to not let water lay in the areas that would normally cause problems in standard spigots, especially near joints and seals. It actually draws water away from these areas, to a safer location.

The most important design feature is that it allows space for expanding water to move so the pressure is much less on the actual spigot/sillock.

They are not perfect, however, as water can sometimes leak from the pressure relief spout, and other places as well. A few dollars can buy you a kit with some replacement seals and other parts to fix that problem. These kits can save you a lot of time and hassle, especially if the spigot/sillock is difficult to access or replace.