We recently moved into a 100 year-old house and are in the process of finishing off the basement. The gas furnace, gas water heater and gas dryer are all located in the basement, which is currently fairly drafty. As we seal up outside air leaks to the basement and install insulation I'm wondering if we should only seal the finished rooms and leave the utility room air leaks alone to allow a supply of air to the furnace, dryer and water heater. That way when these items run the air required for combustion will be un-heated air directly from the outside. Otherwise the air will be sucked through some other crack in the house (such as around a door or window) that will cause that room to be colder. Does this make sense? Or should I just seal up everything as tight as possible? Thanks