I recently moved my water heater to a more central location in the basement to try and get hot water to all places faster. It is now located next to the furnace in the basement (they share the same flue). Now, when I turn on the furnace, I get a slight flue gas odor in the basement like the flue is not drawing. This never happened before, even when it was just the furnace using that vent flue. One other thing changed. When we had the roof redone last year, the roofers lost the rain cap on the furnace vent flue. They replaced it with a different unit that looks to have slots on the side of a round cap rather than the bigger openings on the old unit. Is it possible that this new flue rain cap is more restrictive than the original one?