Because my Potterton Promax 28 boiler is install in the loft it is at the highest point of the system. It is recommended that an Automatic Air Vent Kit 720004701 is fitted. My question is where is it fitted? When I look on the top of the boiler (To the left of Flue Outlet) there is a rubber grommet where the Auto Air Vent should be fitted. When the rubber grommet is removed and I look into the boiler there does not appear to be anywhere directly underneath to connect the Auto Air Vent to. I have ordered the Auto Air Vent Kit and when I receive it, it may be obvious as to where it goes. The Installation and Service Instructions mention the Air Vent but there is no diagram showing it installed. As anybody fitted one of these to a Potterton Promax 28 HE Combi before?