How do i depressurise my boiler?

depends what type of boiler you have theres two ways to do this at the bottom of your boiler there will be a valve with a red cap on, turn this this will release pressure from your system via a 15 mm pipe to the out side. to find this take the cover of your boiler off if possible let down the conrtol unit at the bottom will be behind there some were if its a worschesterbosh under need there is a little white nut turn that with a bucket under neth the valve next to it. if you dont want to try this try bleeding you radiators via the top with a bleed key should be found to the top on the side or to the top behind the front of the radiator hope this helps. your pressure should be between 1 and 1.5 good luck