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rangercap
Supply and Return in older home

My neighbor has an older home (1920s). The supply ducts are located on the inside walls, and returns on the outside walls. From my inspections, there is one return and one supply in each room, including the kitchen. Each is a 9" metal duct.

My question is, would it be possible to reverse the supply and returns, and would this improve heating? Also, there are no dampers. It would be possible to add dampers to each supply in order to balance the system a little better.

Any advice would be appreciated.

Brian

motoguy128
Re: Supply and Return in older home

Just flip the furnace upside down. :D j/k

If nothing else, having shorter return runs is better than supply runs if all the ductwork is the same size. You need more return duct in terms of total area, than supply.

In cold climates it's beneficial to supply heat at the perimeter of the home where the heat loss and gain occurs. It reduces the feeling of drafts and better mixes the air at the point where the air is coldest.

Now, is it worth spending the money to modify the ductwork? I think on a old home, you could put in on a list of things to improve, but it wouldn't be near the top.

Probably something worth changing when the unit gets replaced or upgraded.

The next question is whether or not the ductwork sized adequately and before that, if the furnace is sized correctly.

For example, before 1930, it was common to leave a few windows cracked partly open all winter for fresh air. Following the Flu pandemic, it was believed that fresh air in winter could help prevent getting sick. The boilers or furnaces at the time were sized accordingly.

Sten
Re: Supply and Return in older home

Supplies should always be put on the cold wall (for heat) so they are backwards and yes you can install dampers. Always damper the supplies, never on the return. All joking aside if the ductwork is the same on supplies as returns and you have a multi positional furnace or A/C, it may be feasable or even easier to reverse the furnace , as motoguy states

motoguy128
Re: Supply and Return in older home

That's a good point... on some furnaces it is possbile to mount to blower in several positions, so you could reverse the airflow. However, you'd have to relocate the evap. coil as well.

Sten
Re: Supply and Return in older home

No, not change the blower pos, change the furnace pos, if it is multi positional

canuk
Re: Supply and Return in older home
motoguy128 wrote:

That's a good point... on some furnaces it is possbile to mount to blower in several positions, so you could reverse the airflow. However, you'd have to relocate the evap. coil as well.

You can't reverse the airflow on the furnace.

It was very common in older homes to have the return vent located under the window -- the supply vents on interior walls.
As the years went by , closer studies from building scientists found the opposite arrangement was more benifical for comfort and efficiency.

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