Determine the desired location of the inlet valve and locate the point directly below the centre of the proposed location. Holding the drill vertical and as close to the wall as possible drill a small pilot hole through the floor and sub floor. The straight section of a wire coat hanger cut at an angle makes a good pilot hole drill bit. (Be careful not to snag carpeting.)
Locate this pilot hole from beneath and measure over approximately 2 1/4" (1/2 for drywall + 1 3/4" to centre of the sole plate, that is the base of the wall) adding extra for the thickness of any baseboards. Using a 2 1/2" hole cutter, drill upwards through the flooring and the sole plate. Using a flashlight inspect the interior of the wall to make sure there are no obstructions. Alternatively a piece of tubing can be used to probe for obstructions.
Having determined the location is suitable cut a 2 1/2" X 4 3/8" hole in the wall at the desired inlet valve location. Remove the side portion of the mounting plate by cutting off the plastic with side cutters. Tape low voltage wire to the end of a sufficiently long piece of tubing and pass it up from beneath. If the trunk line is in the attic, tie a weight to the end of the low voltage wire and lower it through the opening. Remove the wire and pass it through the upper hole in the trimmed mounting plate. Bare an inch of both wire leads and wrap them around the lugs on the back of the valve in a clockwise direction. Tighten the lugs with a Philips screwdriver. Run your wire in the walls to the valves before you run the pipe.
Apply cement to the spigot on the back of the mounting plate and attach a short 90 degree fitting oriented in the appropriate direction. Tilt the mounting plate forward and angle it into the hole in the wall. Centre the mounting plate in the hole and pull outward.
Hold the mounting plate in place with a bent coat hanger. Open the valve lid and slide the valve spigot first over the end of the coat hanger. Keep tension on the coat hanger while inserting the valve into the mounting plate with a twisting motion. Do not use glue; the built-in mounting plate gasket will provide a positive seal. Align the screw holes in the valve with those in the mounting plate. Using the screws provided secure the valve in place. Use the extra short screw if the longer screw is going to interfere with the tubing behind. Do not over tighten.
On the floor below apply glue to an adequate length of tubing and aim it upwards through the hole in the sole plate and into the short 90 degree fitting on the back of the mounting plate. Join this branch line to the trunk line using a sweep tee. Note the airflow direction of the tee. When strapping your wire to the pipe, leave several inches loose at the valve. This facilitates servicing the valve by having slack in the wire.
If the inlet valve is to be serviced from the attic, shorter pieces of tubing joined by couplings may be required due to overhead space restrictions. Precut these pieces and work quickly to prevent the cement on the end of the tubing from drying before it reaches the fitting at the valve below.