Plumbing in a washing machine or dishwasher involves tapping an existing water supply pipe and taking a branch from it. This can be done using a conventional compression tee; but if you are plumbing into hot and cold water, as is necessary with many machines, you will have to bend a pipe. An alternative and easier method is to use a thru-flow valve which connects directly to the flexible hose of the machine. Or you can fit a control valve. which is even easier since it does not involve cutting a section out of the supply pipe.

Whichever method you choose, you must first turn off the main stopcock and drain the water from the supply pipes you are going to use.

Using a compression tee

Cut out a 19mm section from the drained supply pipe and insert a 15mm compression tec. From the outlet of the tee take a short length of 15mm pipe to terminate in a stopcock to which the outlet of the flexible hose of the machine is connected. Special washing machine stopcocks with a back plate for fixing to the kitchen wall are available for this purpose.

If you are connecting to the hot and cold water supply pipes of the kitchen sink, you will probably find these run down the kitchen wall parallel to each other and about 100mm apart. This means the branch pipe from the further supply pipe will need to be bent to pass the nearer one. Make two bends within a short distance of each other so the pipe bypasses the other supply pipe.

Fitting a thru-flow valve

The Kontitc thru-flow valve provides a simple means of tapping a 15mm copper water supply pipe for connection to a washing machine, dishwasher or garden hose. The valve incorporates its own 15mm tee junction and one end of the tec has no tube stop.

Before fitting, cut off the water supply and drain the pipe to which the valve is to be connected. Decide on the level at which you want the connection to be made and. with a hacksaw, cut out a section of pipe 28mm long. Cut squarely and file away any burr.

Unscrew the cap nuts and remove the olives from the two compression couplings of the tec: slip the cap nuts, followed by the olives, over the two cut ends of the pipe. You can clip sprung clothes pegs onto the pipes to prevent them slipping down. Apply boss white to the pipe ends and olives.

Pull out the upper length of pipe enough to allow the end of the tee without the tube stop to be pushed over it. Then push back the pipe and allow the valve to slip over the lower section of pipe until held by the tube stop. Tighten up the two compression coupling nuts with a spanner. Make sure the plastic control knob is turned to the ‘off position and turn on the main stopcock.

That is all you need do. A quick release coupling permits the machine hose to be connected or disconnected in an instant. If you have more than one appliance, the same thru-flow valve can be used to supply a dishwasher when the washing machine is not in use.

Fitting a control valve

The Opella plumbing-in kit is an alternative method of connecting a washing machine or dishwasher to a 15mm copper supply. It is a relatively easy method since it does not involve cutting the supply pipe – you simply drill a hole in it.

First cut off the water supply and drain the pipes to which the machine is to be connected. Decide on the point at which the hose connection is to be made and remove any paint from the pipe at this point, then clean with fine emery cloth.

Mark the centre of the hole on the front of the pipe with a centre punch, tapping the punch lightly with a hammer to avoid kinking the pipe. Carefully drill an 8mm hole at this point. making sure the hole is central, and do not allow the drill bit to pass through the pipe to damage the back. Place the back plate of the fitting behind the hole in the pipe, checking it is correctly positioned by inserting the pipe inlet in the front plate in the hole and ensuring the screw holes align. Check the rubber seal round the pipe inlet is in position; tighten the fixing screws and fix the back plate to the wall, using the screws and wall plugs provided. 3d

To complete the operation, screw the tap body into the front plate. You can adjust the position of the outlet if necessary by removing one or more of the washers on the tail of the tap.

This simple method does to some extent restrict the flow of water through the hose. If you wish to use this type of fitting but want a more conventional connection to the water supply pipe, you can cut the pipe and insert a 15 x 15mm compression tec with a 15mm female iron threaded outlet into which the tap body can be screwed. Wrap PTFE thread scaling tape round the threads of the tap tail to make a watertight joint. To ensure stability, use a tee joint with a wall-fitting back plate or clip the supply pipe to the wall at a point within 25mm of the connection.

Providing drainage

You can dispose of the water from a washing machine or dishwasher by hooking the outlet hose over the kitchen sink. If the machine is not near a sink, however, install a stand pipe outlet and hook the outlet hose of the machine permanently into it. Make the stand pipe with 38mm PVC tubing at least 600mm long. A trap should be provided at the base and the outlet taken either to an external gully or, where the kitchen is on an upper floor, to the main stack pipe of a single stack drainage system. Remember to consult the building control officer of your local council before making any connection to a single stack drainage system.

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