As summer temperatures rise, so do electric bills.

Follow these steps to test the performance of your HVAC unit.

The outdoor temperature should be above 80 degrees, and you should set your thermostat well below the room temperature to ensure the system runs long enough for this test. Allow the system to run at least 15 minutes before starting the test proceudres. It is important that the HVAC return filters are clean and non-restrictive.*

1Using a digital probe thermometer (about $12), measure the temperature of the air being pulled into your HVAC return filter. Allow at least 1 minute for the thermometer temperature reading to stablize.

2Measure the temperature of the air blowing out of the supply register (A/C vent) that is nearest the return filter where you took your measurement in step 1. You may also take temperture readings at multiple supply registers and use the average. Again, allow 1 minute for the thermometer temperature reading to stablize at each register.

3Subtract the supply (A/C vent) temperature from the HVAC return filter temperature. You should see a difference of about 14 to 20 degrees. If the difference is significantly out of range (+/- 4 degrees), you may need a licensed HVAC technician to inspect the unit and/or ductwork.

*A non-restrictive HVAC return filter is the non-pleated, inexpensive filter found at most stores that sell HVAC filters.