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Oh, no! The heat strips kicked on!

February 04, 2021

The Weather Channel is forecasting an arctic blast, and your mind automatically snaps to auxiliary mode – the one on your heat pump, that is. A hefty utility bill is what you fear because you know auxiliary mode requires more energy than the normal operations of your heat pump.

But did you know auxiliary mode is a normal function for your heat pump? And did you know it kicks in well before the temperature reaches an extreme?

For heat pump newbies, auxiliary or “aux mode” is the function of your heat pump that turns on the electric heat strips. Heat strips are the supplemental heat sources in the air handler that operate much like the heating element in an electric stove. Auxiliary mode turns on automatically when the outdoor temperature dips to about 40 degrees.

Auxiliary heat is an automatic function and should not be confused with emergency heat, a setting you can control on your thermostat. With emergency heat running, the outdoor unit is locked, and heat is provided by the heat strips only. This function will take an unusual toll on your utility bill and should be reserved for occasions when you have no other source of heat, such as when your compressor fails.

Auxiliary heat turns on your electric heat strips for the following reasons:

  • Run time:  Most thermostats feature programming that automatically turns on the electric heat strips if the system runs for more than a certain amount of time – about 15 minutes – without raising the temperature more than half a degree. This is the most common reason heat strips turn on.
  • On demand: Heat strips also turn on when the thermostat setting is increased by more than three degrees at once. To reduce the demand for the heat strips to kick on, raise the temperature on the thermostat in two-degree increments.
  • To defrost: When your heat pump operates in heat mode, frost can develop on the condenser outside and turn to ice. At that point, the amount of warm air produced by the heat pump is greatly reduced. To counteract this issue, after it reaches a certain temperature, the condenser thaws itself by switching to air conditioning mode. Switching from heating to cooling mode forces hot refrigerant to the condenser where it melts the ice. To prevent a blast of cold air inside the house, the heat strips come on to balance the temperature.

While you can’t prevent your heat pump from shifting to auxiliary mode, you can take steps to ensure your heat pump runs efficiently – and more cost-efficiently – as cold temperatures move into North Alabama. The Tennessee Valley Authority offers the following advice for improving your home’s energy efficiency:

  • Let there be light: Keep curtains open on the south side of the house and closed on the north during the day to trap the warming sunlight.
  • Increase your home’s IQ: Install an Energy Star certified programmable thermostat.
  • Steady as you go: Set your thermostat to 68 degrees. Turn it down even more when no one is home for several days.
  • Bundle up: Insulate heating and cooling ducts and repair any air leaks. Add insulation to your attic, crawlspaces and any accessible exterior walls.
  • Keep it clean: Change air filters monthly. Dirty filters force your heating system to work harder.
  • Seal it up: Caulk and weather-strip around windows and doors and install insulating gaskets to exterior light switches and electrical outlets to stop air leaks.
  • Family meals: Take advantage of the heat generated by cooking.
  • Close the damper: Don’t send warm air up the chimney. Make sure the fireplace damper is closed when not in use.
  • Decorate: Use area rugs if you have hardwood or tile floors to keep your feet warm.
  • Create breathing room: Keep weeds and debris away from the outdoor unit of your heating system.

Alabama Power recommends these additional tips for saving energy and maximizing the comfort of your home year-round:

  • Change air filters more frequently if you have pets.
  • Turn off ceiling fans when you leave a room to cut back unnecessary energy usage.
  • Set the thermostat and then forget it. If you change the temperature often during the day, you are more likely to waste energy.
  • Have your equipment checked by a qualified dealer each year before the heating or cooling season begins. Even the best insulated home will waste energy unless special attention is given to the efficiency of its mechanical equipment.
  • Get your duct system inspected and repaired if necessary.
  • Vacuum refrigerator condenser coils to improve efficiency.
  • Choose to buy new equipment instead of repairing it if it’s more than 15 years old and has had continuing major repairs. Today’s energy-efficient equipment can save enough in operating costs to make up quickly for the initial expense. Consider a heat pump, the most advanced and efficient heating and cooling system available today.

At Air Care Systems, our certified technicians are available to check your heating system with 24-hour emergency services available. We service all makes and models and stand by our work with a 100 percent certification guarantee.

Call us anytime you need us at (256) 537-9987. We offer 24/7 emergency HVAC service for Huntsville, Athens & Decatur, AL. And remember, our middle name is “Care” for a reason.