How do i increase the pressure in my boiler?

You need to find the 'filling loop' - thats the connection to the boiler from the house water main. Its usually a steel braided pipe with a tap on of some kind that you open to allow water to fill your boiler. Don't overdo the pressure though - excess water will just have to be drained out again. You also should look for leaks in your system - the water must have gone somewhere....

John
April 2008