Frost-Free Yard Hydrant

Overview

A frost-free yard hydrant delivers outdoor water through freezing winters by putting its shutoff valve underground, below the frost line, instead of at the spout. The user operates it from the surface, but the actual sealing happens at the bottom of a buried standpipe, and after each use the riser drains itself so there is no water left above the frost line to freeze and split the hydrant.

At grade, the frost-free-hydrant-head carries the spout, the lift handle and the lever linkage. Raising the handle pulls the frost-free-hydrant-operating-rod the full depth of the frost-free-hydrant-standpipe to open the buried frost-free-hydrant-valve. The frost-free-hydrant-weep-hole at the valve body lets the standpipe empty after shutoff, and the frost-free-hydrant-inlet joins the valve to the supply line.

How it works

When the user lifts the handle, the lever linkage draws the operating rod upward. The rod is coupled to the frost-free-hydrant-plunger, which lifts off the brass frost-free-hydrant-valve-seat and lets supply water rise up the standpipe and out the spout. Because the valve sits below the frost line, the seal and the standing supply water are always in unfrozen ground.

Lowering the handle pushes the plunger back down onto the seat and shuts off flow. At that moment the small frost-free-hydrant-weep-hole in the valve body is uncovered, and the water remaining in the standpipe drains out through it into the surrounding gravel bed. Within moments the riser is empty, so even in deep cold there is no trapped water above grade to freeze. An O-ring seals the plunger as it strokes, and adjustable stem packing seals the operating rod where it leaves the head.

This self-draining behavior is the whole point of the design, and it is why a frost-free hydrant must be installed with a gravel drainage pocket and must never have a hose left pressurized on the spout over a freeze, which would block the weep hole and let the standpipe fill and freeze.