problem with our boiler, hope someone can help. the hot water takes a very long time before it comes on, ive noticed the pressure gauge is always sitting at 0. we have had the boiler for 7 years, and was serviced last summer. i was under the impression that one could re-pressurise the boiler by turning a knob from underneath the boiler, there are two underneath, turning these has no effect. So is this a job for a professional, or anything else i can try? the service is due for this year, im thinking i may mention it to the service engineer at the same time, but will it be an expensive job? Thanks.