If you want to connect up a washing machine that uses hot and cold water (and therefore has a hot & cold valve) but you only have a cold water supply, you can use a Y Piece connector to connect it up to a single cold water tap.
The washing machine will then work OK, but it may take longer to wash than normal. However, you may also get better wash results if it takes longer to wash. Simply screw the Y-Piece onto the tap, and then screw the hot and cold fill hoses to the Y-piece and connect the other end of the fill hoses to the washing machine. (You may also be able to buy this part from a DIY store like B&Q)
Points to watch
If you don’t connect a water supply to the hot valve (and simply connect the cold water hose to the cold valve leaving the hot valve with nothing connected to it) then some wash programs may not work as some programmes only fill with hot water. However, some washing machines will work OK with only the cold fill hose connected. You can always try it and see. The worse that will happen is the washer could either stick on the odd wash programme or may abort on some. If you do this though it’s possible for water to drip out of the hot valve on some machines during fill. It’s best to use a y-piece if possible.
The fact that you have connected cold water to the hot valve is irrelevant, the washing machine will not know any different and will just heat the water up to the correct temperature. The washing machine may use slightly more electricity but if it’s less than 10 years old it shouldn’t be significant unless you use a lot of 60 or 90 degree washes. On 40 degree washes, manufacturers argue it’s more efficient to fill with cold water only and slowly heat up the water to 40 degrees.