You need a heating contractor that understands air duct design.
Add air conditioning to second floor.
However if the heater you have is not able to handle the extra square footage then your best bet is getting a bigger heater and air conditioning unit.
Window ac units are quite affordable too.
Add a small return vent duct to each room on the second floor.
Positioning a window air conditioner in those places will allow the unit to better regulate the heat on your second floor.
Ceiling fans are a mild consolation.
Depending on the size you get you can spend as little as 150 or a good unit and less than 20 each month to run it every day.
While window air conditioners were certainly popular at one time today it is generally preferable to use a ductless system.
For 1 the furnace fan running all day with the a c on might solve some milder heat trap problems for your second floor.
Divide the house into two zones one for each floor.
Using separate central air conditioning units for each floor allows you to.
They circulate the warm air but do not cool it and even add a little heat to the room.
For instance for air conditioning to work properly air returns the large ducts that carry air back to the central unit need to be installed high up on the wall of each upper floor to capture.
One mistake people make is thinking they can just add a vent and the heating problem will be solved.
Ensure that the air conditioning unit is on and wait one hour.
You might also want to try adding a ceiling fan in critical rooms like a second floor bedroom.
If your heater can handle the extra vent go for it.
The first step your contractor will take to determine the position of ducts is to draw a floor plan of the second floor and lay it over a floor plan of the first floor.
Adding more to an adequate amount will do very little.
Check the temperature of the second floor rooms.
So what is the solution to a hot upstairs where the second floor rooms need more air conditioning.
You can choose second floor air conditioning units such as a window air conditioner or a ductless system in order to provide the cooling comfort you need.