hello there. We have had a Glow worm Flexi com 30CX combi boiler recently fitted. All worked well, it seemed. But then it stopped working due to lack of pressure. Possibly dropping since day one. Topped up pressure easily enough then contacted the installer. The installer has tried to find any leakage to no avail. He now wants to put in a additive to block any leaks. What leaks if no pipes are leaking then surely the pressure drop is in the boiler. and seeing as it is new, surely an additive to block leaks would not be the best thing to be putting in it. Does this sound silly? Should he be seeing if the manufacture condones such actions under its warranty? I would like to add that he pressurized and isolated the system and the pressure did not drop. Do new boilers loose pressure? Is it a common fault? What should I be asking him to try? Or not to do? I don't want to shorten the life of our new boiler. Thanks for any advice.