If you get f40, hold in the reset button for approx 10 seconds until ts appears. Then press the reset button again. P-01 should flash. Press the top + button. Then press the minus button to change the parameters. You should then see 00 appear and the boiler may kick in if the water pressure is run on a switch. If it is run on a sensor you will need to press the top + to get it to 01. The boiler may again kick in if it's run on a sensor. If the boiler kicks in hold the reset button for approx 15 seconds to set these as the parameters.
Paul Barker, September 2010