Hello,
I was told that you can lower heating costs in the winter if you block the upper return air vents in your house. Both of my bedrooms have 2 vents, 1 about 6 inches from the floor and 1 about 6 inches from ceiling. Is there any damger in doing this?

I did purchase some magnetic vent covers, but figured I'd ask before I used them.

~Hal

From what you described, one is a return and the other is a supply. Blocking either one will serve only to make the room colder as it will affect the air trurnover in the room. If you do not plan to use the room, I suppose you could close them off, but you will have some impact on other rooms supplied by the same duct system. I highly doubt you will see much savings by closing off a return unless you also close the door to the room as air will travel to another return in an attempt to balance itself. In a properly balanced system, closing off supplies and returns could have the opposite effect by creating warm/cool spots in the rest of the system.

you want to block the bottom vents in the summer and the top in the winter. There is no danger in doing this. Ideally they should have installed closing type vents on these for exactly that purpose. Yes it will help save some money. Not a lot but will help. It really will make the room more comfortable.

The 2 rooms I referenced are on the West side of the house and are naturally a couple degrees cooler in the winter then al the other rooms in the house. I'm hoping that not only to save a couple bucks on heating, but also keep these 2 rooms a little warmer and more comfortable to sleep in during the winter.

As for the vents themselves...The bottom vents are closing type vents, but the tops are not. That's why I bought the magnetic vent covers.

~Hal

Just close them in the summer then. The amount of friction from the duct will make the air or at least most of it pull from the bottom when the grill is open. close it during the summer to pull the heat off the ceiling. Using the plastic covers on the grills is a waste of money then. As what they cost will hardly ever be recooped in energy savings. The primary reason for the high low returns is comfort not savings. Although some savings can be had, it will be just to little to notice in the gas usage.
If your looking to save money. Put up paddle fans. The fan will mix the air for comfort, cool you in the summer with a nice breeze and lower your cooling bill. And if the ceiling is high enough pull down any wasted heat that is near the ceiling. Again saving money.