Vent, Valve & Volt
No heat in the house at all

This one needs a licensed pro

Stop: a burning or electrical smell

A burning plastic or hot wiring smell is a safety problem. Turn the furnace off and have an HVAC technician check it before you run it again.

Why this happens

Trane says a burning plastic smell from a furnace can mean an electrical problem, such as the casing on the wires melting, and calls it a big safety hazard. Carrier says burning plastic or an electrical odor can come from an overheated blower motor or damaged wiring, and recommends you stop using the furnace until a qualified HVAC professional inspects it.

What to do right now

  1. If you see smoke or flames, or the smell gets much stronger, get everyone out and call 911 from outside. If you smell gas or rotten eggs, leave now without touching any switch and call 911 or your gas utility from outside.
  2. Set the thermostat to Off.
  3. Carrier says to shut off power to the furnace. If its power switch is on the outside of the furnace or on a nearby wall, and you can reach it with dry hands, away from any smoke, heat or scorch marks, switch it off. If you can't do that easily, skip it.
  4. If the smell lingers while you wait, Carrier suggests running exhaust fans or cracking a few windows, because burning plastic can give off fumes that can be toxic.
  5. If the smell is strongest at an outlet, a switch or something plugged in, not at the furnace, don't touch or unplug anything there yet. Use the outlet burning smell guide, or the warm switch or outlet guide for a switch, both linked below. Each one turns the breaker off first.
  6. Don't open the furnace or try to find the problem yourself. Call an HVAC technician.

When to stop. If you smell gas or rotten eggs, leave the house without touching any switch and call 911 or your gas utility from outside. If a carbon monoxide alarm sounds, or anyone feels dizzy, sick or has a headache, get everyone outside to fresh air and call 911. If you see smoke or flames, get out and call 911. Don't turn the furnace back on until an HVAC technician has inspected it.

What to tell the HVAC technician

  • What the smell was like and where it was strongest: the vents, the furnace or somewhere else.
  • Whether it started when the furnace turned on, or the heat had already stopped.
  • Any hum, grinding or other new sound before the heat stopped.
  • The furnace brand, model and serial from its label.

Build the full list: what to tell the HVAC technician.

Related troubleshooters

Start this troubleshooter over

References (every fact above comes from one of these pages)
  1. Trane: Furnace smells like burning
  2. Carrier: Burning smell in house
  3. American Red Cross: What to do if a fire starts
  4. American Gas Association: Using natural gas safely
  5. CPSC: Carbon monoxide information center

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