I had a similar problem with my Morco feb 24e - the boiler fired up ran for a few seconds on either hot water or central heating, then made a loud wooshing and banging noise and the whole system cut out and would not reset until the unit cooled down. Local plumber on the site claimed it was the the thermistor on the central heating side. The problem was actually the water pump which was not running efficiently - I replaced the pump with a spare one from Morco and had no more problems. I think the central heating water pump must run even for hot water only, to circulate water through the central heating heat exchanger to prevent it boiling or something similar...
Robert Staines, March 2013