Improving Your Air Conditioner

Why Does The Temperature Go Up When My Air Conditioner Starts?

If you watch your thermostat when your air conditioner first starts running, you may notice that it goes up a few degrees before it starts to go down. This may be perfectly natural, or it may be the sign of a serious problem. Here's how to tell the difference.

Natural Causes of a Thermostat Jump

To understand why a thermostat might jump up, it's important to understand how a central air conditioning system works. All of the cooled air is sent out into your vents by a central blower. It gets the air that it cools from a single intake vent located near the blower.

When the air conditioner runs, the intake vent acts like a giant vacuum sucking warm air out of your house. Often, it is pulling in air that was near your sunlit windows and is typically warmer than the air in the shady interior of your house near the intake vent.

So, as the warm air is pulled in from throughout your home, the temperature near the intake vent goes up. Because the thermostat is usually placed next to the intake vent, you'll see a temperature increase.

Uninsulated Ducts

Another source of hot air might come from your ducts. Your attic is typically well over 100 degrees, and your air ducts will be heated up from the radiant heat.

When the air conditioner starts up again, the heated air will first be blown out into your home before cool air starts flowing behind it. This is more than just a temporary nuisance.

If your ducts are getting hot enough that the air initially blowing out of them causes a noticeable temperature swing, you are losing a lot of energy efficiency. Your air conditioned air is also being heated and not coming out as cold. Have your ducts insulated as soon as possible.

Drafts and Air Leaks

Temperature swings might also be a sign of drafty windows, doors that aren't properly sealed, or other air leaks. When your air conditioner starts up, the suction pulls in hot air from the outside in through these holes. This leaves your air conditioner fighting to cool outside air as well as inside air.

Annually check your caulking and weatherstripping to ensure that your home is airtight for energy efficiency.

To have your air conditioner inspected to see if it's working properly or to schedule energy efficiency improvements, contact a local HVAC contractor today. Click here to learn more about air conditioning.   


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