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An inexpensive method of creating a side flow off a main flow of water is by use of a saddle valve. The installation may often be performed by a homeowner without the services of a plumber. Not all jurisdictions allow the use of a saddle valve, however.
The valve consists of a two-piece clamp, a tee junction for the new water flow, and a stem that opens or closes the valve. A self-tapping saddle valve has a sharp, screw-like point on the end of the stem that pierces the tubing without requiring drilling the hole into the tubing. Tubing refers to pipe of less than 1 inch in diameter. A typical installation is on a piece of copper pipe or tubing that is the cold-water feed to a sink or the water heater or any nearby cold water line. Hot water is not tapped, as it is more likely to clog the small opening of the valve with salts.
The principle uses of saddle valves are to provide water to an appliance such as an ice make, cooler, filter, or water softener. A humidifier to a furnace also requires a water feed that might be supplied by use of a saddle valve on a nearby water line. The location of the valve is chosen based on the cold-water feed available, distance to the appliance, and accessibility to the valve.
In many installations, a self-tapping saddle valve with a tee joint is used. For small-diameter copper tubing, the self-tapping feature may be sufficient to provide a reliable flow of water. For larger tubing, pipes, or non-copper installations, manufacturers may suggest that the penetration into the supply feed be drilled before placing the saddle valve. The feed source pipe should be drained before installation.
Two clamps, when screwed together, encircle the pipe. The curved shape of the clamps gives the saddle valve its name. A rubber gasket is placed over the piercing screw point of the stem of the self-tapping saddle valve and the clamps tightened evenly. Once tightly positioned, with the rubber gasket slightly compressed, the stem is tightened until it pierces the tubing wall and finally can be turned no more. For non-self-tapping valves, the rubber gasket is positioned over the pre-drilled hole.
The feed to the appliance, often plastic tubing, is fastened to the tee of the valve by use of a ferrule and a nut. Flow out of the tubing should be measured to ensure it meets the appliance manufacturer’s requirements before the appliance is installed. This may be done by timing the filling of the water in a large measuring cup, juice container, or other marked container. The stem should always be in a full open position to minimize deposits.