How to Install a Frost-Proof Faucet Outdoors

Call first for local plumbing rules

When you upgrade a sill cock, call your plumbing inspector to check on local requirements. (You may need a permit, too.) Although plumbing codes and enforcement vary around the country, generally they require:

• Three-quarter inch (minimum) inside diameter supply pipes to each sill cock. Some local codes only require 1/2-in. pipe and a 1/2-in. sill cock.
• Either an approved vacuum breaker that permanently attaches to standard sill cocks (step 11) or a sill cock with the feature built in (step 7) to prevent siphoning.
• A shutoff valve, also called a “stop” valve, to serve each sill cock. Our code required us to install a shutoff with a built-in drain known as a “stop and waste” valve (Figure B, below).
• If you have galvanized steel pipe and must make a transition to copper, install a special dielectric fitting (step 8) to prevent corrosion.

Freeze-Proof Strategy

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The frost-proof feature works by shutting off water flow back at the stem bottom (inside a heated space). The anti-siphon feature is built into the water spigot. Install the sill cock through a wall with a slight downward pitch to allow any remaining water to drain out through the water spigot.

Make a sketch and a parts list

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Measure your existing plumbing and list the inside diameter of the existing pipe, the thickness of the outside wall, the linear feet of new pipe and the types of fittings needed.

Draw where each pipe and fitting goes; indicate whether a part has threaded, sweat or solvent-welded joints; and label its size and description (for example, 3/4-in. copper female adapter). Then sketch the new plumbing layout to use for a materials list.

Make a shopping list

If you have galvanized pipe, we recommend you unscrew the pipe back at the first coupling or fitting (steps 3 – 6). Then insert a dielectric fitting (step 8) and convert to copper pipe and fittings all the way back through to the sill cock.

Frost-proof, anti-siphon sill cocks are available in 1/2-in. and 3/4-in. inside diameters, and 8-in., 10-in. and 12-in. lengths (step 7). Choose the diameter required by your local code and a length that will accommodate the thickness of your outside wall plus give you some working room inside to attach pipe and fittings.

We also installed a 3/4-in. “full-port” (for unobstructed water flow) ball valve with drain. There’s no neoprene washer to wear out, and the easy-to-turn handle shows whether the valve is open or closed (step 9).

Putting it all together: Remove the old water spigot

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Turn off either the water shutoff valve to the existing sill cock or the main water supply. Open the sill cock and drain the water from the line. Remove the old outdoor water faucet sill cock by positioning a pipe wrench at the back of the sill cock and turning the wrench counterclockwise. Have an assistant use a pipe wrench to hold back the sill cock supply line inside to prevent sections of pipe from unscrewing.

Turn off the next pipe

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Unscrew the old pipe at the joint closest to the outside wall. Hold one side stationary with one pipe wrench and twist off the pipe with the other. Remove as many couplings and pipes as needed to fit in the new assembly (step 8).

Insert the new sill cock

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Bore a 1-1/8 in. hole (if the hole needs enlarging) for the new sill cock using a masonry hole saw. Dry-fit the sill cock in an upright position tight against the wall and mark the location of the fastening holes. Drill two 1/4-in. holes with a masonry drill bit and push the plastic screw anchors in flush to the wall. Apply a thick bead of clear silicone around the back of the sill cock flange, push it against the wall and fasten it with two 1-1/4 in. No. 8 roundhead brass screws.

Attach the dielectric fitting

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Start from the old pipe end and work toward the new sill cock. It’s easier to solder copper fittings to copper pipe and then screw them into hard-to-sweat parts like the ball valve and sill cock.

Disassemble the dielectric fitting and solder one end to a 6-in. copper pipe. Cool the pipe and reassemble the fitting. Then solder the copper male adapter to the other end. Apply pipe tape to the threads of the galvanized pipe and tightly screw the dielectric fitting to the pipe.

Assemble the pipe and fittings

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Apply pipe tape to the male adapter threads on the 6-in. pipe (shown in the previous step), and screw the “stop and waste” ball valve to it. The water flow direction arrow on the valve must point toward the sill cock. Solder a male adapter to a 12-in. copper pipe, apply pipe tape to the adapter threads and screw it into the other side of the ball valve. Temporarily screw a female adapter to the sill cock and slide a female coupling halfway onto the end of the 12-in. pipe. Then measure the distance between them, add 1 in. and cut a section of 3/4-in. copper pipe to fit.

Sweat the copper

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Solder on the 3/4-in. coupling last. Remove the female adapter and solder it to the copper pipe. Then apply pipe tape to the male threads, and screw the adapter onto the sill cock. Solder both copper pipes into the coupling. When sweating the copper joints, open the sill cock, hold the torch on one side of the connection and the lead-free solder wire on the other side. Heat the joint for 10 seconds until the solder melts and flows around the connection. Loosen the pipe hangers along the pipe system to allow maximum movement to fit this last connection.

Install an anti-siphon valve on an existing sill cock

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Depending on how your outdoor water faucet sill cock is currently plumbed, you may find that purchasing and installing an anti-siphon valve (also called a vacuum breaker) is all you need. Don’t apply any pipe tape or compound on the sill cock spout threads. To prevent accidental removal or tampering by vandals, all plumbing codes require that vacuum breakers be permanently installed. The breaker you buy will have either a setscrew (with a break-off head) that grips the spout threads or a feature to make it hard to unscrew the breaker once it’s installed.

If you have a CPVC supply system:

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If you have a CPVC supply system (as shown above in Figure B), omit the dielectric fitting, buy a plastic shutoff valve (with drain) and solvent-weld the pipe and fittings together. Position the valve so that its water flow direction arrow points toward the outside wall.

More installation tips

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For the best results:

• To install freeze-proof water spigot through brick or concrete foundations, it may be necessary to enlarge the existing hole using a drill with a masonry hole saw. When drilling the larger hole, control drill wobble or “kick-out” by gripping the drill with two hands, keeping the hole saw centered on the old hole and running the drill at a lower speed when the saw first enters the hole.
• Apply pipe compound or pipe tape to the male pipe threads everywhere that threaded pipe and fittings join.
• Install new pipe level with the existing piping when they’re inside a heated space. Install pipes on a downward slope if they drain toward an open sill cock once they leave the heated space.
• Space pipe hangers every 3 ft. to support the pipe. Use copper or plastic hangers on copper pipe.
• After replumbing the sill cock, turn the water on for at least two minutes to flush out impurities.
• Uncouple your garden hose from the sill cock before winter. If hoses remain attached, frostproof sill cocks (whether open or closed) may freeze because water can’t completely drain out of them.