in my boiler room in a 2 family house there are 2 gas hot water baseboard boilers and two gas hot water heater. There is a gas like smell "rotten eggs", local gas company detects no leaks. The smell is tramendus and all the copper pipes are blue. don't know if the blue pipes are releated to the smell or do I have multiple problems. The main question I have is what could cause the outside of all the copper pipes to turn blue?