How Do Freezeless Post Yard Hydrants Work?

Freeze-proof hydrants provide outside water year 'round.

In areas of the country which have winters cold enough to freeze the soil for long periods of time, frost-free hydrants are used as outdoor water spigots which function regardless of the cold.

Function

The most popular models of frost-free hydrants work by activating a lever on the above-ground head of the hydrant. Pull it up and the water flows, push it down and the water shuts off. It's that simple. How it functions without freezing is the interesting part.

Underground Works

The actual on/off valve of the hydrant is buried deep underground at the end of a long pipe. The control lever on the head of the hydrant connects to the underground valve with a steel rod located inside the stand pipe. There's a drain hole in the underground valve that plugs shut when the water is turned on but opens when the water is shut off. Once the water stops flowing, the drain hole opens and the water remaining in the stand pipe and above ground head, drains out before it can freeze and clog the pipe or hydrant head.

Frost Depth

The depth to which the soil freezes during the winter varies. The frozen layer may be 5 feet or more in the northern states with long, cold winters; the ground may only freeze several inches deep in the mid-south. You need to purchase a freezeless hydrant with a stand pipe long enough to position the bottom valve and drain deeper than the soil is expected to freeze. Local plumbing shops stock normally stock hydrants long enough to function in their area.

References

• Simmons Manufacturing: Hydrant Lengths

Resources

• Woodford Manufacturing: How a Freeze Proof Hydrant Works