Tip 20: More Air Conditioner Information
In the last issue we talked about normal maintenance that all residents should be doing, such as changing filters and washing the condenser fins. In this issue, we will discuss some of the things you can do when using your air conditioner to get the most out of it.
The temperature at which you set the thermostat will affect how much it costs to run your air conditioner. Mine is set at 78°, which we find comfortable. For every degree you set the thermostat below that number, you will use 6% more energy. My brother likes his house cooled to 72°. His electric bill for cooling his house is more than one-third more than mine. In the winter heating season, I set the thermostat at 68°, with nighttime set back to 63°.
The air conditioner does two things to make your house comfortable. It lowers the temperature and it lowers the humidity. When the temperature outside is high, say 90°, the air conditioner will run about 45 minutes out of every hour. This will bring your indoor temperature down to the setting on your thermostat, say 78°. It will also lower the humidity by condensing it on the outside of the evaporator in the furnace the way a cold drink sweats on a humid day. It does this for the 45 minutes of each hour that the air conditioner runs. When the temperature outside is 80°, the air conditioner will only run about 12 minutes of each hour. The indoor temperature will come down to the thermostat setting, say 78°, but with the short run times, not much of the humidity is removed from the air. That is why on a humid day with an outside temperature only a few degrees above the thermostat setting, you may not feel as comfortable as when the outside temperature is ten or more degrees above the thermostat setting.
The houses in Sun City seem to have the air conditioners properly sized. We discussed this at the woodshop and no one seemed to have a problem. The biggest problem with poor sizing is air conditioners that are too large. If three tons is good, four tons is better…NOT. The problem with a too large air conditioner is that it will not run enough to remove the humidity. I mention this because it will be time soon to start replacing the air conditioners in some of the older neighborhoods. Don’t put in a larger unit, as you may end up without enough run time to remove the humidity.
Ceiling fans cool the occupants of a room by passing air over the skin, which evaporates moisture, cooling the skin. This is the same phenomenon that makes you feel cooler on a hot day when a breeze is blowing. With a ceiling fan running in a room, you can set the thermostat 2° warmer and feel just as comfortable while enjoying a 12% reduction in energy costs. When you leave the room, you are no longer cooled by the fan’s breeze. The room is not being cooled by the fan, in fact, it is actually being heated. The motor on the fan gives off a small amount of heat that adds heat to the room. Now that you know the basic heat transfer of a ceiling fan, you should turn it off when no one is in the room.
If you use the fan in the winter, be sure to reverse the fan direction. In the summer, you want the air to blow down so that you have a breeze across your skin. In the winter, the fan blows upward to move the warmer air near the ceiling outward and down the walls to where you live in the room so that you feel warmer.
You can reduce the heat load on rooms in your house by closing the blinds when the sun is shining through south or west facing windows. This will reduce the load on your air conditioner and save you electricity.
If you have suggestions for future tips or have questions about maintenance around your home, submit them to firstname.lastname@example.org