Hi, had a plumber come over to recharge the expansion vessel for my hot water tank. After the recharge, when the taps were opened, brown water spluttered out of taps for about 3 minutes. The plumber seemed a bit confused about this and suggested that if it continues it may be a torn membrane in the expansion vessel. Since then the water has been running clear but I've found a drop in pressure in some taps, not all, and hot showers intermittently going cold for a few seconds. Both are new occurrences. Any idea what is happening. FYI it's the white expansion vessel that was recharged.