Hi I had a Baxi combi 105 HE fitted over a year ago and it has never worked properly since it was installed, It will heat up the central heating but the water to the sinks and to the bath are either cold or just warm, I've tried turning the thermostat up and had plumber out numerous times, but still the problem is still happening, also the system keeps loosing pressure and there are no leaks anywhere, I'm was wondering is this a common fault on this make of combi boiler, please could someone give me some advice on how to get it fixed. Thanks