I have a Potterton Puma 80 boiler and it wont fire. Initially the boiler was showing low pressure warning light, pressure gauge was was up in 4 bar, i bled a radiator and got it down to 1.5 bars but still the low pressure light was showing. I was told the water pressure switch may need cleaning. I then read a post on a forum that said a few light taps with a hammer may dislodge any dirt, I did this, turned boiler on and indeed the low pressure warning light had gone, however the boiler still did not fire up, then the pilot light went out. I left it for 1/2 hr turned it back on light the pilot light and the system fired up fine. This morning (2 days later) the boiler wont fire up again and the low pressure system light is still not showing, pressure dropped slightly to 1 bar, ive re-pressurized to 1.5 and still nothing. Can someone shed some light on the possible problem and way to resolve it. I am going to clean/replace water pressure switch as this may have become blocked. thanks.