Reducing Heating Costs


I live alone in a large 2000 square feet home with four bedrooms, central air and heat with heat pump in North Texas. I think I remember somebody from the electric company one time telling me that it was not a good idea to shut off rooms you are not using by closing vents and doors to reduce the cost of heating and air conditioning. Is that really true or is it okay to do that except when you expect freezing weather? My home uses all electric and the bills seem to get higher and higher.
Don't Do It

I've been in the A/C and Heating business in Southeast Texas for nearly 30 years. In my opinion, closing off vents not in use is not a good idea. I could go into the technical aspects of design problems with duct rating. But the bottom line is that your unit will actually work harder, your energy bill will increase, and the life of the unit would be decreased with vents closed. However, I can think of no reason why you couldn't just close the blinds/curtains and a shut the doors thereby decreasing the heat load for those particular rooms, which may actually cause a decrease in your energy bill.
Focus on Maintenance

Try having the A/C unit cleaned. The coils could be partly plugged, which would cause the unit to run longer to heat or cool the house. If you have had any of the vents closed, you should have someone check the ductwork to make sure it is intact. I closed a vent in my father's house and it blew the duct loose from the A/C unit and was cooling the attic.
Not a Good Practice

My advisor from our local public utility company told me this is NOT a good practice since the warm or cold air will leak into the unused room anyway. They told me the way to go is to find the "turn off or close fin" located somewhere in the duct. You can find it because it is a small turnkey type of lever. Shut the vent that way, then you can close off the room.
Reduce Cooling Costs

Here in Texas there is absolutely no reason to heat the unused rooms in your house. The one exception to this rule is if you have freezing weather and poorly insulated pipes. In that case, the cost of repairing frozen pipes will cost far more than your electricity will. You can avoid this by wrapping your pipes with heat cables. They look like tape with an electrical heating element in them. You simply wrap the pipes and plug them in. This allows you to go ahead and close off the extra rooms.

What I suspect you heard before is that you should not close off your non-air-conditioned rooms. This is because the humidity builds up and can cause mold and mildew growth. It also takes a long time for the air conditioner to remove the humidity from the air when you open your vents again thus using up all your savings plus more.

The best way to lower your air conditioning costs is to use fans and turn the air conditioner up a few degrees. A seasonal check up of your air conditioning and heating system is also useful in keeping your system running at peak efficiency. It is absolutely essential for safety for everyone who has a gas heating system.
Need the Correct Size Unit

When I had the air ducts redone in my house a few years back, the technicians advised us to refrain from closing off the vents completely in unused rooms. The reason has to do with the hot and cold air not being able to flow freely through the system. A closed vent creates a blockage, which causes the forced air back up and makes the unit run less efficiently. This will in turn promote premature wear and tear. I also live in an all-electric house in North Texas and know how extreme the weather can be here. I would like to share some tips that have worked for me.
Use the heat and A/C only during the hours when it's needed most.

We also keep the thermostat at 68 degrees in the winter and 85 degrees in the summer.

These two things should help tremendously! Also be sure to caulk and weather-strip!
Seal Your Windows and Doors

We have that kind of unit, too. It is not a good thing to do with your kind of heating and air. If you had individual room window/wall units, then it would be a good thing. Since your unit was put in according to the size of your house, it still wants to take in a certain amount of air per minute. Your system is working hard because it is still trying to pull the air from the closed rooms to the central intake vent to make its "goal". You may also want to check the size of your unit. A too small unit can run up the bill and severely decrease the life of the unit. For a 2,000 sq. ft house, your unit should be about 4 tons (about 1 ton for 500 sq. ft).

By shutting off rooms, you are also trapping moisture and creating growths in your ducts that will not be good for your health. Your best bet will be to open your doors and vents. Make sure your windows are sealed and caulked well. Make some of those things that sit in the bottom of the windows or roll up some old towel and put them in the windows. They also make a plastic cover type thing that you can seal your window with if you want to go that far.
Invest in a Programmable Thermostat

We invested in an electronic programmable thermostat. They aren't real expensive and they are worth their cost in heating/cooling savings. Since we're gone about 9 hours each day during the work week, we program it to 75 degrees during the summer days and 62 degrees during the winter days. It's programmed to change to a reasonable temperature about 30 minutes before we arrive home. So we don't really notice much change except in our bill. With electric, you may find that 30 minutes is not enough to cool or warm up your house before you get home. Weekends can be programmed separately depending on your use of the house on those days. If you aren't away from your house, then this may not work for you.