Air in system?

Hi, any help would be welcome please.

Have a Worcester 24CDi combi, just over 3.5 years old. Had Worcester Bosch engineer out earlier this year to repair slight water leak from the boiler (£210 ), but all has been fine since . However, for the last few days the HOT tap on the bathroom sink has been acting very strangely. You turn it on and nothing happens for 2/3 turns, then all of a sudden water fires out at about 100 miles an hour! Kids are frightened to use the tap and anyone who dares risk it has to wear wellies and a plastic mac!

Is this just a simple problem like a washer? (the tap has had a slight drip for a while), or is it due to air trapped in the system. Absolutely no knowledge of plumbing whatsoever (in case you hadn't guessed) - so any advice would be appreciated - thank you in anticipation.

washer is getting stuck on seat of tap. Strip it down clean and replace washer.

OK - thanks will do that today.

Hi me again - another question please - as it's the bathroom sink hot tap we're dealing with - do we need to TURN OFF the combi boiler before turning off the stopcock under the sink, will the boiler be damaged if we leave it on? Thanks for your help.

i am not a plumber or heating engineer but it would be a wise precaution