we have a Baxi Bermuda back boiler hot water and central heating its very old. 37 years. but in good working order. I drained the water off today to hopefully change a radiator in bathroom for a towel rail, but when i filled the system up again, the central heating worked fine, but i cannot get hot water now, and the pump is making a louder noise than usual. we have only lived in this house for 6 months, but i feel the system has not been disturbed in years till today, can anyone advise. or help.