I have built four rooms in my basement, one has a gas fireplace installed in it, one is a bathroom with a vent to the outside, one bedroom and one rec room. I have tapped off the main heat duct and installed diffusors in the center of each rooms ceiling. I am now in the process of installing cold air returns. I understand that I do not need a cold air return in the bathroom. Should I run returns to the other three rooms or is one centralized return sufficient. The total square footage of the three rooms is about 740 sq/ft. Where do I put the returns? At floor level or can I have them on the ceiling. Getting them to the floor is going to be extremely difficult the way I have the rooms framed. Any input would be very helpful. Thanks, Dan.

Returns work best up high. Hot air rises. In the winter you want to pull the hot air down from th ceiling and recirculate it. In the summer you want to pull it down and cool it.

You can have either a central return or individual returns in each room. If you have a central return the heating and cooling will be affected whether doors are open or closed.
You probably want to have both the supply and returns in this area smaller than in the rest of the house because you are so close the furnace.

You don't put returns in baths and kitchens. You don't want to pull oders from these areas into the rest of the house.

I do have a question to ask you on your changes to the basement... where is your furnace getting it's combustion air from?? Now that you have built rooms within the basement? I sure hope that it is a 90% eff. Furnace that is taking it's combustion air from outside the basement ! What about your water heater?? Looking for your reply, and concerned about your safety!!

My Furnace is 92% efficient and is getting is combustion air from outside, so is the water heater. I appreciated your concern.

Returns work best up high. Hot air rises. In the winter you want to pull the hot air down from th ceiling and recirculate it. In the summer you want to pull it down and cool it.

You can have either a central return or individual returns in each room. If you have a central return the heating and cooling will be affected whether doors are open or closed.
You probably want to have both the supply and returns in this area smaller than in the rest of the house because you are so close the the furnace.

You don't put returns in baths and kitchens. You don't want to pull oders from these areas into the rest of the house.

So the returns can be on the ceiling? How far away from the supplies should they be?

As far as possible. I you have your supplies in the center of the ceiling, put a return in the wall or in the ceiling close to the wall.

So the returns can be on the ceiling? How far away from the supplies should they be

As far away as possible to prevent recirculation problems.

I can still move the supplies. If I move them to the outside walls, the returns would be easy to install in the ceiling next to the inside wall. I appreciate the feedback.

Sounds like a plan So do it!

((I can still move the supplies. If I move them to the outside walls, the returns would be easy to install in the ceiling next to the inside wall. I appreciate the feedback))

I have installed furnaces and usually put supplies along outside walls -- one or two per wall

Depending on amount of windows area -- heat rises along outside walls -- returns are on

Inside walls... Most basements have concrete walls and floors and should be harder to

Heat than a main level with wood floors... Agree with putting supply on outer wall and

Return in middle -- most heat is at ceiling and not heating floor... Just wondering how

To adjust the system to where both areas are heated -- doesn't the added basement area

Affect the way the system operates

Well I haven't opened the supplies to the basement yet, so I don't now how it will function.