I am losing pressure on my boiler I fill it to no 2 and within two hours it is bottoming out I have done the paper around the radiators and checked for any signs of damp . This has been going on for almost a week I have had my boiler checked and also a local plumber has been they both say a leak but I must have lost 40 litres of water and no were is damp . I recently had a combi shower fitted and the water pressure was to powerful and was pushing cold water back through the hot pipe the plumber came and fitted pressure reducers to my system could this have affected my system as I had no problem previously??