Rooms Missing Return Air Vent

Heating and cooling ducts run through an attic

Dave asks,

We purchased a house about 10 years ago and since have found several significant problems. It was inspected as part of the purchase, and none of these issues were identified. One that I just noticed recently is that several rooms do not have return air vent ducts to the furnace. Some have registers that are not connected to the furnace and some do not have registers at all.

I have heard there is a way to run small (3”) hoses through the walls to correct this problem. Do you have any additional information on this topic? Thanks.

Our Answer

Not all homes have return air vents in every room. In fact most forced air heating and cooling system use one or two centrally located return air vents, typically in a hallway or other space central to the home. You mentioned that some rooms have registers that do not appear connected to the HVAC system. These may or may not be return air vents. It’s a bit difficult to tell, but here’s an easy test. Make sure the HVAC system is running full blast (i the summer, you can simply turn the thermostat all the way down and visa-versa in the winter). Then take a tissue and hold it against the return, then let it go. If it stick to the register, then this is in fact working as a return. The tissue helps you spot airflow back into the uct system.

I have also seen registers used to simply circulate heating or cooling from the room above or below without being connected to the HVAC system.

As for your question about the 3″ ducts, you may be referring ot a SpacePak HVAC system. This is a small duct high velocity system which is popular when retrofitting older homes as the ducts can be run inside existing wall cavities with very little damage. it is not a solution for a home that has inadequate return ducts. If that is the case here, you be better off running a new central return duct. Air will naturally be drawn back to the return from the rooms you mentioned. Just make sure there is a 1″ gap under the door to the room.

However, despite everything I have told you, I dont know what the problem is you are trying to solve. If rooms are too hot, or too cold, for example, there may be another solution entirely. Comment below with any additional information.

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Community Answers

Joan

I have what looks like a stairwell wall vent that is not connected to any air/heat tubing but is open to the space where the Air/heating system is located in the garage behind the wall. It looks like it was cut out of the wall and covered with a vent cover. As a result the cold air from the garage keeps the basement room very cold in the winter. Is this vent cutout necessary or can it be covered up?

Reply
- Tom Kraeutler
  
  Yes, it is necessary. What you’ve described is a combustion air vent. It’s designed t bring fresh air into the heating system so that it burns cleanly and safely. It wold be potentially dangerous to block t.
  
  Reply