I have a hot air furnace and need to get some info on my upstairs cold air return problems.?

Question

I have a 3 level home, cellar, main, and upstairs. My hot air furnace heats the main properly and has the thermostat, but the upstairs north facing bedrooms remain cold in the winter. There are 4 cold air returns on main floor, but none upstairs, except the spiral stairwell. I have a pellet stove that runs in the cellar that keeps the main floor supplemented and warmer, thus not kicking on the air furnace too often. I put two open floor grates to let some cold air go into the cellar from the main floor, and I also tried putting a grate in my son's upstairs bedroom floor to allow some cold air to move downstairs. None of this has seemed to help the problem and it's still only 63 upstairs in his room. I know the pellet stove is keeping the furnace from starting, but how can I get that cold air to leave the north bedrooms upstairs? There are 3 heat registers upstairs including one in my son's room. I thought that putting the grate in his room would get some of the air moving.

Answer 1

Where does the grate in the bedroom lead to? If it's just a hole in the floor the cold air has no place to go. It has to be connected by ductwoork to the return air of the furnace. Otherwise the cold air will stay put. But putting ductwork from the 2nd floor would be a massive job.

You'd be better of to get something like a portable quartz air heater for the bedroom and just turn it on an hour before bedtime.