You need to connect a piece of hose from one tap to the other in the kitchen sink. Then turn on the hot tap first and then the cold tap and wait a few minutes and the pressure from the mains will force any air out of the hot pipes.
Or if you have a mixer taps in your kitchen sink then its even easier, just plug the spout with something and hold in place and turn the taps on as outlined above.
Or if you have a mixer taps in your kitchen sink then its even easier, just plug the spout with something and hold in place and turn the taps on as outlined above.