Q: We purchased a house built in 1987. The crawlspace is sealed because it is used as a general return for the systems. There is a sump pump in the corner of the crawlspace.
My questions: 1) Should the general air return, now in the crawlspace, be changed for the heating and air-conditioning systems? 2) If you do recommend changing the return, should we purchase a more energy-efficient furnace, since ours is one installed in 1987?
A. Using a sealed crawlspace for the cold-air return not only saves on the installation costs of ductwork but the movement of air helps to keep the crawl environment dry.
A dry crawlspace will also protect you from an overly active insect infestation.
Unfortunately, the crawlspace you described is not sealed. An open sump pit in the crawlspace more than likely has drain tiles attached that extend around the interior perimeter of the foundation and are installed under the vapor barrier. An open sump pit can be the source of odors due to stagnant water in the pipes.
Seal the pit tightly and install a ventilation pipe to the outside of the home.
Another source of odors is bacteria that is present in the gravel and soils.
Ideally, the vapor barrier should be on top of the rocks; a second vapor barrier can be installed on top of the gravel.
Because your crawlspace is a cold-air return, I would not recommend that you install ductwork. You want to maintain the constant exchange of the air in the crawlspace as long as the air is clean and free of odors.
Send questions to d.Barnett(at)insightbb.com.
