Why is there a vent on the ductwork coming right from the furnace? I have a typical furnace for a 1400sqft house in Michigan. I also have central air which runs through the same duct work. There is a separate room in the basement for the furnace, hot water tank and workshop area. No one ever spends much time in that room if any. Should I leave the vent open for both heat and air conditioning or should it be open for one/closed for the other? Please let me know. Thank youenter image description here enter image description here

  • if it's an intake, leave it open. if it's indeed a vent, and un-used, close up that waste asap – dandavis Jan 30 '18 at 8:28
  • It's not an intake, it's blowing out hot air right now because I'm using it for my boots and gloves dryer lol the reason I ask though is because how close it is in the start off the duct work. As well I have done little research and it sounds like you don't want to close of to many vents depending on your system because closing off to many will cause to much back pressure or something. – Christopher Jan 30 '18 at 10:40
  • So it's a vent to condition the space--heat in winter and a/c in summer--and it has an adjustable damper on it so you can control how much air comes out. – Jim Stewart Jan 30 '18 at 11:13
  • if you have several closed off, you can adjust the fan speed to reduce pressure. many of those $99 "fall specials" from HVAC companies include adjustments along with the safety inspection. – dandavis Jan 30 '18 at 11:20

Furnace installers and/or home owners will put a register in the duct work to provide some heat in the winter to that area. The number of these supply registers is determined by the typical use and desired temperature of this area. I recommend that all basements should have at least 2 supply registers and 1 return register in the basement/equipment area just to keep that area slightly warm and the air fresh. If you are going to finish that area to be used as living space, then more supply and returns will be needed. Also you may want to close the supply registers in the summer when using the A/C since cold air is heavy and will move to the lowest level in the house. Keeping the register you originally inquired about either open or closed would be your choice.

  • Any chance that register is there to help prevent pipes from freezing? – elrobis Jan 30 '18 at 15:00
  • It's there to help prevent anything that shouldn't freeze from freezing. In many homes it's the only heat supply in an unfinished basement. Use it as appropriate. – isherwood Jan 30 '18 at 18:10
  • Works very nicely in an otherwise unheated basement. – Wayfaring Stranger Jan 31 '18 at 3:38

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