Finally after 8 yrs of service the weather was just right that my L73's intake iced up and I got smell in the house. Called my service man and he said he was getting up to 8 calls a day because of iced intakes. Seems the weather this past week was just right for this to happen. He suggested removing the air intake hose off the chimney and let it breath from inside the house. Within 5 minutes the exhaust had warmed the intake and melted the ice and I re-installed the intake on the Chimney and everything was good, no more smell.