boiler keeps going till it steams up?

You seem to be describing multipule faults there.

"keeps needing a top up of water"

Check all radiator valves, under boiler for leaks etc, check copper pipe outside (see if it has been dicharging water. If it has look towards Presssure Relief Valve or Expansion Vessel)



"turn heating on and it keeps burning until it steams up and locks out but not heating any of the pipes"

Is the pump running? Sounds like a pump problem



"hot water works if you reset but the when you turn water off it bubbles and gurgles and steams up again then locks itself out"

This may also be a pump problem however if it it working...Behind the PCB there is a round brass housing (diaphragm) and coming out of the side there is a hexagonal brass tube with a spring and pin located inside this. Get someone to open the hot tap a few times to see if this pin is moving freely. If it isnt moving the diapgram may be faulty. If it is opening then not closing quick enough when you close the hot tap try putting some silicone grease in the spring area. (WD40 is an OKish alternative)

Paul
March 2010