After bleeding the radiators the pressure on the boiler dropped below 1 bar. I had to partially refill the boiler. I realised then that water was escaping through the vent hole on the cap of the aav. I tightened the cap to stop the leak. Now I find, when the CH is on, that the water pressure is usually around 2.8 bar, but sometimes exceeds 3 bar.
Does this sound as though I need a new aav?
Should I normally leave the aav open slightly?