The ductwork in our house is screwed up. The master bedroom gets way to hot with the heat on as compared to the rest of the house.

My quick and cheap solution is to close the vents into the bedroom and crack open a window.

My question is: Does the hot air in the room run out the window or is the cold air from the outside running in or a combination of both?

 

Probably both, when the heat is on, the pressure forces air into the return(s) but if have the window open, its another place air can escape. Then when the heat is off, any wind from the outside can blow cold air inside.

 

"C" ... displacement theory.

You need a HVAC technician with an airflow tester. They can determine the values in each room and suggest resizing ductwork or adjusting dampers (if available) to achieve a better balance. With proper planning, the entire house can be within 1 degree of dead center with not only even temperatures, but good circulation as well.

 

it could be due to how close the HVAC handlers are to the master bedroom. I had this issue with flow with my HVAC and the HVAC company put a dampening panel in the duct work to help divert more air to the other rooms on that floor's ductwork.

As far as the windows go, it's a waste of energy to open your window up since the heat is simply going out the window.

 

^ Thanks for all the feedback. I'm still on the cheap method... closing the registers and cracking a window. If may be an extra $40 a month in power, but that's a long way from the $9700 of a new system that was quoted.

 

Opening a window isn't necessarily wasting as much money as you might think b/c you are simply neutralizing the temperature in that room alone. Ideally, you would have the same air flow to all rooms, so you are wasting some heat by sending extra of it to the room that is being cancelled by the open window. However, I highly doubt that the increased percentage of air that is making it to the bedroom and being wasted will account for that much money.

Now if you were leaving a window open in the same room as your thermostat, I would suggest reconsidering your plan to save money. In the long run (years) it will eventually cost you more to not fix it. Unless 2012 really happens, then you will come out ahead, but you will also be dead.