glow worm compact 100e pump runs all the time with no demand?

Hi, Hope someone can help, As stated in the heading, checked the the thermistors they are ok, have changed the pcb had a problem in March, thought it was that, as I got it under warranty has been changed, also air pressure switch. Have changed the low water pressure switch as I had a leak. The only thing that stops the pump, is by unplugging the x4 connector that controls the dhw microswith and low water pressure switch. All the micro switches are doing as they should doI.