Why Does My Heat Smell Like Burning? Auxiliary Heat Strip Guide
Why Does My Heat Smell Like Burning? Auxiliary Heat Strip Guide
By Jordan Heating & Air • Serving Central North Carolina Since 1928
Quick Answer | AI Overview Summary
Heat pumps use high-resistance electric nickel-chromium coils as auxiliary emergency heat when outdoor temperatures drop below freezing. Because aux coils only run on the coldest nights, they accumulate dust and operate at much higher surface temperatures than regular heat pump cycles, creating an intense hot metal odor that requires clean airflow.
What Are Auxiliary Heat Strips and When Do They Turn On?
Unlike a gas furnace that generates raw flame, an electric heat pump moves heat from outside air into your home. When outdoor temperatures drop into the 20s in Asheboro, heat pump capacity drops. Your system activates auxiliary electric resistance coils located inside the indoor air handler. These 5kW to 20kW coils glow red-hot to supplement heating and maintain thermostat setpoints.
Why Auxiliary Heat Smells More Intense Than Standard Heating
Because auxiliary coils only energize during sub-freezing mornings or when the outdoor unit enters defrost cycle, they gather dust, pet dander, and moisture between infrequent runs. When 240 volts of electricity hit these bare nickel-chromium coils, surface temperatures exceed 1,000 degrees Fahrenheit, creating an abrupt, noticeable scorched metallic odor.
Danger Signs: Melted Sequencers and Restricted Airflow
If your aux heat smells like sweet melting plastic, your heat strip sequencer relay or high-limit safety switch may be sticking. Clogged air filters choke off return airflow across the coils, causing internal temperatures to spike until thermal limit switches trip. If the smell does not fade after 15 minutes of heating, turn your thermostat from HEAT to OFF and call for service.
Frequently Asked Questions
Is auxiliary heat more expensive to run than regular heat pump mode?
Yes, auxiliary heat uses pure electrical resistance, which operates at a 1:1 efficiency ratio (COP of 1.0). Regular heat pump mode operates between 2.5 to 3.5 COP, making auxiliary heat up to three times more expensive per hour.
Why does my thermostat say AUX HEAT during defrost mode?
When your outdoor heat pump unit frosts over in cold weather, it temporarily reverses into cooling mode to melt the ice. The system automatically turns on indoor auxiliary heat strips so cold air is not blown through your living room vents.
Should I ever switch my thermostat to EMERGENCY HEAT manually?
Emergency heat should only be used if your outdoor unit is physically broken, covered in thick ice from a winter storm, or making mechanical grinding noises. Otherwise, let your thermostat control auxiliary stages automatically.
Fast Heating Diagnosis in Randolph County
Whether your furnace igniter is cracked or your heat pump auxiliary coils are burning dust, Jordan Heating & Air delivers upfront pricing and 24/7 service.
Call (336) 893-0371 Now
