I am having the same problems as a few people on this site, my low water pressure light came on so i tried the recomended answers on here by disconnecting the yellow wires from the switch, and prestow the unit fired up, i purchased a new switch fitted it and it worked fine got all the air out of the system, it lasted about an Hour and the light came back on, i disconnected the yellow wires again and it worked, could this be a faulty switch or could theere be other problems.

Any help you can give will be much appreciated

Cheers mike

Mike Williams, November 2011

Thanks for getting back so quick, i released the pressure as the radiators were getting hot so that could be the problem,it is running at the moment with the yellow wire disconected from the switch until we get the house warm i will then switch it off

Cheers

Mike, November 2011

At what point did you get the air out of the system? If while the system was hot, when it cooled, the pressure would drop, needs to be done when cold, set the pressure, then as it heats, pressure will increase, but go back to normal when cold rather than going low when cold.

SD, November 2011