Running your Air Conditioner when its 100+ Degrees Outside

Here in Houston we just set a record for a straight 15 days in a row with daytime temperatures reaching or exceeding 100 degrees Fahrenheit. Yes it’s hot, and air conditioners are taxed to their performance limits to try to keep up with cool air demands. Here’s some things you need to know about running your AC unit in these kinds of conditions.

Should Your AC Unit be Bigger? No!

Central air conditioning systems are designed to suite the size of your home and the amount of air it needs to cool or heat. The size of the specific AC unit, the condenser, is chosen to be efficient for 98% of the typical high temperatures in your area (climate). So for that 2% extreme, like we are having this summer, your AC system may actually be undersized. But this is by design. Otherwise, if you went with a larger system that had no troubles pumping the volumes of cool air needed during these extremely hot days, your system would be quite inefficient 98% of the time. And that’s really almost all the time – not a good thing.

The larger system costs more to install and it consumes more energy to run, all costing you more money. Because it pumps more air volume it cools the house much faster. You might think this was a good thing but instead it means the system is running through off and on cycles at a much higher rate. The shorter cooling cycles means it is not quite running long enough to be pulling humidity out of your home. Removing humidity is part of how an air conditioner works. The condensing coil condenses water out of the air and the heat exchange process during that activity is what creates the cooler air. Warmer air and moisture is then exited from your home. Dryer air, even when warmer, is more comfortable for the human body as it allows our internal air conditioning, evaporation of sweat, to be more efficient. Not removing sufficient humidity from your home could also lead to mold problems.

These are some of the reasons an over-sized AC system is just an all around bad idea. But you can still make the system you have work for you in these 100+ degree conditions.

Juicing More Efficiency out of Your AC System

To make it easier for your AC system to reliably pump out cool air when it’s over 100 degrees outside you need to give it some help. We previously wrote a huge list of tips for energy savings in relation to ac usage. Apply as many of those as you can to help your cooling system cope in this heat.

In a nutshell it comes down to reducing heat gains in the home. Some of the basics are;

  • turn the thermostat up a couple degrees and be happy with 76 to 78 degree temperatures indoors
  • close off unused rooms – close doors and vents – don’t cool what you don’t use
  • shade your windows on the sunny side of the house
  • cook outdoors – enjoy the summer BBQ
  • don’t use dry cycle on dishwasher – leave door open and let them air dry
  • don’t run clothes dryer during the heat of the day
  • read more tips here

Anything you can do to keep the house cooler, even a little bit, means the AC does not need to be running as long for each cooling cycle.

AC Maintenance is KEY!

Your central air system should be getting a maintenance check up at least once a year. Ideally the AC unit should be checked before peak demand in the summer heat, to ensure it’s running at it best when you need it most. It will be running long and hard through these multiple 100+ degrees days and may even need a check up later on after all that heavy use.

If you’ve not had your system serviced yet this year, call your ac contractor (in Houston and area, that’s us) and get it done. But you might need to wait a while, we get very very busy in times like this (does everyone wait till the last minute? Seems they do).

At the very least, go check your filters. Fresh clean filters allow more cool air to flow unobstructed. If the filters are only a little bit dirty, put fresh ones in now for this extreme heat period. You can still reuse those slightly dirty filters if you wish later once the summer begins to die down.