Using magnetic strips on the heating vents.

You might notice a difference ...but may be not. Don’t cover the cold air returns...the furnace needs the air for proper heating

just close the vents

As long as the cover will stay down, this is fine. Why don't you want to use a magnet strip? If you choose, put like a piece of quilting material on the vent, and then something heavy, to hold this down. Best wishes, J.

If you are going to cover cold air return vents, do not. Hot air vents usually have and adjustment lever that you can close your vent and not have to cover. Your best bet is to find your biggest air leak and tackle it.

I wouldn't close off heat in rooms as the cold can increase condensation and lead to mildew or mold growth. Better to do things like insulate your plug covers, caulk windows or cover with plastic sheeting, put reflective window film on windows to hold heat in, get thermal window curtains or honeycomb blinds, seal doors with sealing strips, increase insulation in attic, reverse your ceiling fan to blow hot air down into the room. You can also contact your power company for a free home energy conservation consultation.

Change all your light bulbs to LED ones (dollar tree has them for $1). As you replace appliances buy energy star efficient ones, your power company should have a rebate for each when you replace.

Put all your electronics on a power strip and turn off when you leave room, saves on ghost power use. They also have smart ones that do it automatically now, my power company had them for $5 for each homeowner.

Check to see if your ducts have diverters on them so you can close off warm air to unused rooms. Just make sure any water pipes are not in unheated areas.

Irene, if you are in Seattle, there is no problem in covering up the vents in the rooms that are not being used. This is no different than shutting off the vents with the little flappers than come attached to the backs of some vent covers. The magnet covers you purchased are intended to go over vent covers that do not have any adjusters already attached to them.

Many homes at the west coast in B.C. ( and throughout the U.K.) do not even have central heating, and the damp winter climate is the same. Without central heating, people live with heating only the rooms that they are in, or using at any one time.

As others have noted though, make sure that you are covering just the heating vents, and not the cold air return vents.

Closing off he heaing vents in rooms you don't use will not save any energy costs. It will just cool the rooms down. The furnace will still heat and cool as usual. The thermostat turns the furnace on and off based on the temperature in the room it's in not the rooms you close off. As a matter of fact your costs may increase. As the furnace runs and the air circulates some of the cold air from those rooms would be drawn out from under and around the door mixing with the warm air causing a longer running furnace. Don't forget warm air rises and cold air drops. As the warm air rises it will pull cold air to displace it. Also just closing the heating vents and not the return vents will pull cold air to the furnace and it will run longer to heat the air. Closing both vents will put a strain on the furnace blower and it can fail prematurely.

I've always been told by HVAC professionals not to completely close off your vents. It effects the air flow. You might want to call a professional and just ask them.

Thanks for all the answers.