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?