F9 Glow-worm Flexicom SX?

Evening,
Can anyone help?
Everytime I want our heating to come on I have to go to the boiler to find it flashing Fault 9.
I have to reset it and open the taps until it fires up.
If I turn the thermostat down so it goes off and then want the heating on later, i turn the thermostat back up and agin it won't automatically come on and I have to again open up the taps, does anyone know what the fault might be?
We have tried everything.
Hope someone can help!
Many Thanks