I have a 2-story house built in 2007 with forced heat and central air. The air handler in located on the second floor in a laundry room along with the hot water heater.
There are no return ducts, just a big intake grate in the hallway upstairs. Also, there is just one central duct in the 2nd story floor so the upstairs vents are in the floor and main level vents are in the ceiling.
3 bedrooms upstairs, each has a vent, 2 bathrooms upstairs, each has a vent. Above each bedroom door, there is a flow thru grate that lets air go directly from the rooms to the hallway.
On the main floor there are only 3 vents and one little teeny-tiny one in the basement.
I have been running with all the upstairs ones closed except for the main bedroom and all the main floor ones open. Is this bad? Should I leave them all open?
I dont get why there are 5 vents upstairs and only 3 downstairs, especially when the heat rises. Maybe someone can tell me the theory of this design. I know it is for low cost but I would like to know the machanics of how it is SUPPOSED to work.
I tried opening the little vent in the basement but then the basement would "pressurize" and cold air blows out under the basement door into the kitchen.
What is the best thing I should do in this situation? Anything I can do to make the system better? Also, I want to finish the basement but I am sure the little vent down there isn't enough to heat it.