Hi. I am having an issue with my water heater and would like some advice. Water heater is LP gas, located a few inches away from the basement wall with a vertical rise of 18 inches going straight up to the elbow with a proper pitch. All piping going out of the house meets code, doubled wall pipe, exhaust pipe above roof. I live in New York and if the weather is very cold (0-20 degrees or so) the fumes occasionally can be smelled in the basement. When this happens, the pipes are cold and have condensation, if I open the outside door to provide a draft then the pipe warms up and the fumes go up the exhaust pipe. However, now it seems that this is happening occasionally when the weather is in the lower 30s. My house is not super tight or energy efficient so a draft issue shouldn't really be a problem. There is no blockage in the vent pipes. I have a carbon monoxide monitor and it has never gone off. I am looking for a solution to this problem. Could it possibly have anything to do with my heater being older and maybe doesn't burn as hot as it should to warm the exhaust pipe in cold weather? Could replacing this water heater with a new one be a solution to the problem? Thank you