The compost chamber draws in fresh air and exhausts it to the outside. If the composter is inside a house with a wood stove and/or gas water heater that are also competing for inside air, you may have lower air pressure inside the house than outside. This can pull cold air down the composter vent and into the house. Composters shouldn’t smell bad, and something is wrong if they do, but you don’t want to flavor your house with their gaseous by-products either. Do the smart thing: Give your wood stove outside air for combustion. This will give an energy efficiency and comfort boost as well, by turning down the airspeed on all the cold drafts through every crevice that must
otherwise provide the air supply for your wood stove.
Insulate the composter’s vent stack where it passes through any unheated spaces. The warm, humid air passing up the stack will condense on cold vent walls, and moisture will run back down into the compost chamber. Most manufacturers include vent pipe and some insulation with their kits. Add more insulation if needed for your particular installation.