Sizing return air supply
I'm currently finishing up a plumbing project in my house and happened to learn a little more about the HVAC supply and returns in my house, after openning up parts of walls and ceilings.
My upstairs is hard to cool and heat.
Just a got a new unit 2.5 tons, up form 2 tons. Its a small 2 story townhouse.
What i learned about my HVAC is they use the wall and floor cavities in some places as the air and return duct. The one return duct i have the most access to is the return from the master bedroom. What i notice is that it comes down the second floor wall( the vent is located at the top of the wall), then turns 90 uses the floor cavity(maybe 10ft run) then back into a first floor, and then down again into the basement.
Wondering if going from a wall cavity to a larger floor cavity(twice its size) then back to a wall cavity would limit the air return?
i think my unit has enough push to get up to the second floor, i think the return is not enough.
There is returns in all 3 bedrooms, and a large return on the first floor.
Would running a duct in the floor/ceiling cavity, trying to better match the wall cavity size make a better flow?