Reader Interactions


  1. My daughter is in the process of remodeling a house. It is two story, about 2,600sf. Her husband had to do a total gut before starting. They put in a large single air return in the basement, about 30″x30″. There is no return on the top floor, just an open staircase to the basement (living spaces).
    Since the “other” grand dad was in heating and air conditioning they followed his ideas. I suggested that each room should have had its own ceiling air return so the warm air would be used more efficiently, and it should stop the drafts associated with all the air in the house funneling through the house to the floor height return.
    I get cussed out suggesting that I think it would be better. The other grandpa just keeps repeating hot air always rises. Well it also conducts and radiates, and this reheating of the cold air causes the furnace to work harder.
    I am persona non grata when it come to furnaces.

    Is it better to use individual ceiling hieght returns in each room? Our 1950’s era home needs a new furnace and I was thinking of routing returns high on the walls or in the ceiling. We only have 800sf to deal with, but it is heated very un-uniform during our 5 months of ice. There are two floor mounted returns in the living room, none in the other rooms.

    We did insulate the house. After we bought it we found out that none of the walls were insulated. At that time the furnace ran 24/7. When I found the crawl space heated to 65 F I added insulation under the house. That is a big improvement.

    • Hi Don. I apologize for a delay but I was away for a long weekend + a little more. You are absolutely correct with the air returns in each of the rooms. This would dramatically improve air circulation and help to equalize temperature through the whole house.

      They should at least install a single air return port on the main floor so the air has a way of being recirculated. Single returns used to work in older, poorly insulated homes with a lot of air leaks. All those gaps and holes allowed the heated air to escape and make room for more heated air (it’s called stack effect). Newer (or newly remodeled) homes are much tighter, thus keeping all the air inside, which requires circulation.
      Even one properly sized air return on that main floor will help them stay comfortable. Ideally (if using heating and cooling), double air returns located in the upper(or ceiling) and lower sections of the wall perform best.

  2. We are in negotiations on a house where the inspector showed us an open return by the furnace in a 1.5 story house. No ductwork. It looks to my uneducated in HVAC eye like an open metal trough that sucks air into it. The inspector said it may create a carbon monoxide hazard. I would like to have the company who installed and services it come in and explain why it’s right or wrong. Also considering an opinion from an uninvolved company. Any thoughts or suggestions?

    • Hi Rindie,
      An open return by the furnace issue is always associated with the setup of the area this furnace and maybe some other gas burning appliances are located in. It has also to do with the combustion air required for the gas (and other fossil fuels) burning process. Forced air furnace air return must be a min of 10’ from the firebox (furnace burner chamber, water heater burner chamber, fireplace firebox, etc.) and from the draft hood (water heater, some boilers, and furnaces), or located in a separate room (not in a bathroom, closet, bedroom, kitchen, garage, mechanical room).
      This requirement applies in situations where fuel burning appliances rely entirely on the combustion air from within the room they are located in. For the appliances using house exterior combustion air only and equipped with sealed combustion chambers (high efficiency furnaces with two PVC pipes, high efficiency water heaters with exhaust and air intake pipes, etc.) this wouldn’t be necessary.
      The 10’ forced air furnace air return opening distance is required to minimize the possibility of creating a negative pressure within the area surrounding the appliance. This negative pressure could create a backdraft through the draft hoods and combustion chambers of the appliances. In an air tight / well weather sealed home this could result in exhaust gases (might contain Carbon Monoxide) being sucked back in to the house from the vent pipes / chimney, and distributed through the house by the air circulating system.
      Another problem is the combustion air requirement – without the proper amount of oxygen / air being removed / diluted by the return port from the area surrounding the appliances, Carbon Monoxide might develop during the burning process. With the air return being so close, CO could be distributed through the house.
      So, besides the air return port being too close to the fire box / draft hood, you have to make sure that all of the fuel burning appliances are provided with an adequate amount of combustion air – read that post!
      Let me know if this fully answers your questions and if there’s anything else I can help you with…

Leave a Reply

Your email address will not be published.