When the combustion air duct is connected directly to the return plenum for a furnace, the blower fan on the furnace pulls outdoor air in to the return plenum. To supply this air to the furnace room, ...

To fully understand how to install a high-velocity HVAC system, one must know what it is and what it does. Basically, it is a small duct, high-velocity airflow, heating and cooling system designed to ...

Q: I’m confused about maintenance of my crawlspace, which also serves as a cold-air return plenum for an oil furnace. No cold-air return ducts, just crawlspace. The crawlspace looks quite dirty, and ...