If you have a mixer tap you need to put the palm of your hand over the end of the tap to stop water coming out.
Turn on the hot water tap fully. You will feel no pressure on your hand. keeping your hand firmly clamped around the end of the tap, slowly turn on the cold water.
This will start to force water back up the hot tap pipes to expel any air and fill the pipes with water.
Do this for about 10 seconds.
Turn off the cold water first, then the hot. You can now release the end of the tap. do this quickly as there may be enough pressure to get you wet, not much.
You should now be able to turn on the hot water with pressure back to normal. The water will run cold at first so let it run until hot at tap. Hope this helps.
If you have 2 seperate taps you will need to connect them with a short piece of hose pipe, then do the same procedure.
Garyfshutt, May 2009