We have a hot water boiler at Church which is used about twice a week for tea/coffee. When we turn it on we get a "fishy" smell emanating from it. We used to leave the boiler full but from time to time it would leak and flood the kitchen (never worked out whether it was the tap leaking or the inlet valve sticking occasionally). We then started leaving it empty. The smell seems to occur with either it left full or empty.
Any suggestions as to cause/remedy or is it time for a new unit?