Last year I purchased a 50-year-old home. Central air and heating were installed about 12 to 15 years ago, which included five vents in the basement. I had an energy conservation expert from the local electric company do a survey of the home. He suggested that I seal off all five vents in the basement since there was no living space down there. A little later my HVAC expert came to examine the system. He said I needed to keep those vents open as the system was designed to move air through those vents. Otherwise, I was building up too much pressure, causing extra strain on my HVAC system. What's the best way to go? How can I be the most energy-efficient and save money in the long run?
Our Answer
Generally speaking, shutting off registers should not add any kind of strain to the system. One thing to be aware of with respect to basement ducting: Make sure any return registers are left open because that pulls air back to the heating system to be reheated and re-cooled. That would include any damp air in the basement, which keeps the basement drier. One caution with regard to basement returns: An HVAC expert should make sure they’re not located too close to the furnace, as that can cause the room to depressurize and combustion gases to be drawn into the house.
With all that said, I don’t expect you to get a significant savings on AC by shutting off the basement registers because the thermostat that controls whether the system is on or off is most likely upstairs, away from that room.
I cut a vent in basement HVAC duct to have heat in the winter and a/c in the summer. Now it’s summer and I notice condensation collecting on the vent when A/C is running. We keep the basement door from kitchen closed and I’ve also noticed that the top of the stairwell has alot of heat. Should I put a vent in the kitchen’s basement door to let the heat come the rest of the way upstairs where the return is? I did have HVAC technician install a vent in the return duct in the basement unit [14″x14″] but it is inside a closet I made when I finished the basement. There are double, louvered doors hanging up at closet. I thought that would allowed and heat toget to the return, but apparently not.
(there is a space between the foundation and floor joist running the length of the crawl space in the basement closet where the indoor unit is. So should I seal that space to help keep the crawl space air from coming into closet where the indoor unit is?