We have lost pressure in the boiler. It heats water no problem at all but I think due to the lack of pressure the CH does not function upstairs only downstairs. The manual shows two inlet/outlet points at the top of the boiler for re-pressurising. What I would like to know is how do I do that? Is there a particular pressurising pump for this boiler. If so where can I get hold of one and what is it called? What would be the recommended pressure setting on normal running conditions?