Troydn93

Help - I am 2 years into owning my fabulous boat and have encountered my first big problem. Similar to last year I have drained my water tank in preparation for winter following recommendations for winterising. As the weather has been mild I decided to refill the tank and take the boat out for a long weekend but although the cold water runs in the kitchen and bathrooms, the hot water is only a trickle and the pump pulses when hot is turned on. I have two bathrooms with flushing toilets (on board waste tank) and both flushes have stopped working too - the pump sounds but no water flows. Now the cold water tap in one of the bathrooms has also started to be just a trickle and the pump pulses when it is turned on. In the other bathroom the cold tap, when turned on, produces water with black granules. We replaced the pump with a new one but this has not solved the problem. The pulsing is 2 seconds on, 2 seconds off. The hot water is heated with a calorifier and the boat has central heating via radiators. Could anyone help with suggestions?