My 6 month old worcester junior 24i has started to make a noise which sounds like there\\\'s grit passing through it! I\\\'m sure that\\\'s not what it is but that is what it sounds like. It started a few days ago, then stopped and has now resumed, albeit a little bit quieter. The sound is not in the pipes anywhere. I live in a one bed flat which has 1 shower, 2 basins (bathroom & kitchen) and 4 radiators. NO bath. Any ideas?