It is now 42 Below and the pilot light keeps going out. It is because there is a backdraft of cold air coming out of the flue. The water heater is located in the downstairs utility room in a 2 story home. The flue or stack is 4 in diameter, first going horizontal for 26 then vertical outside for 20 feet past the roof. It is also double walled and has a isulated chase until the last 3 or 4 feet. When the pilot light is lit and the gas turned on the constant rush of cold air pushes the exhaust (carbon monoxide) back in to the house. It is also visual because of the temperature of the draft, and can smell it. I need to know how to get the exhaust to go up the flue. Someone has suggested a pipe fan but it would only suck the warm air out of the utility room causing yet another problem. Please help.