Why does my heater smell when I first turn it on?

Quick Answer

A brief dusty, hot smell the first time heat runs in the fall is usually dust burning off parts that sat idle all summer. It should fade within about an hour. A strong or lasting burning smell means turn the heat off. A rotten-egg smell means leave the house right away.

What you can safely check

Safety first — sort the smell before anything else: -Rotten eggs:do not investigate, do not flip switches, do not use a phone inside the house. Get everyone and pets out. Call 911 and the gas utility from outside (Q97). If you are even asking yourself whether a smell is "dust or eggs," treat it as eggs. -Strong, sharp, electric or plastic burning smell. Or any burning smell that keeps coming back:turn the heat off and call for service. If you see smoke or actual fire: leave, then 911. -Dusty, hot smell on the season's first run:this is the normal one. Notice its type and duration, open a window for a few minutes. Let it fade. - Do not open heating system to hunt for a smell's source. - If the smell comes with weak heat, check the filter. A clogged filter can overheat a furnace (Q33).

What might be causing this

Three smells arrive with first heat, and they have three completely different responses. Learn them before the cold night, not during it.

The normal one: dust. All summer, dust settles on the heat exchanger, the heating elements. The duct surfaces near the registers. The heat exchanger is the metal chamber inside the furnace where fuel burns. The first firing of the season burns that dust off. The result is a dusty, hot, faintly scorched smell. Like a hair dryer or a dusty attic. It is at its strongest in the first minutes. It should fade within roughly an hour of running. Opening a window for a few minutes is the entire remedy. Learn its boundaries, because they are what make it safe to recognize. It starts with the season's first heat. It is dusty rather than sharp or chemical. And it goes away. A dusty smell that returns on later runs is not burn-off. Burn-off happens once. And belongs to the warning family. A test run on a mild day (Q40) burns the dust off early, on purpose.

The warning one: a strong, sharp, electric or plastic burning odor. Or the dusty smell that keeps returning, or grows stronger. Either can mean overheating parts, electric trouble. A blower straining against a clogged filter (compare Q20). That smell does not get the benefit of the doubt. And it does not get run "to see whether it burns off eventually."

The emergency one: rotten eggs. Natural gas has no odor of its own, so a sulfur smell is added to it deliberately, as a built-in alarm. If that is the smell, the response is the leave-first protocol in the checks above. Nothing in your heater is worth one more breath of a possible gas leak.

A closing fact puts all three in perspective: carbon monoxide has no smell at all. Carbon monoxide is a poisonous gas produced when fuel burns incompletely. It has no color and no smell, so you cannot detect it yourself. The most dangerous heating byproduct gives your nose nothing to work with. That is why working CO alarms. Tested and in date. Are part of every fuel-burning home's first-heat routine (Q98). It is also why heating inspections check the combustion parts (Q63).

When to call a professional

Call for the warning family: any strong, sharp, or recurring burning smell, with the heat off while you wait. A technician will inspect the blower and motor, electric connections. The heat exchanger and combustion parts — the places overheating and burning smells come from. The emergency family does not wait for a technician at all: that call is 911 and the gas utility, from outside.

What happens next

Smell sorted as normal burn-off? You are ready for winter — Q40's checklist finishes the job. Sorted as the warning kind? Ask Texas Heat & Air what you will get in writing, and what your approval covers, before you book.

Texas Heat & Air next step

Smell sorted as the warning kind? Heat off and call Texas Heat & Air at (682) 438-8127. Sorted as rotten eggs? Outside first — the call is 911.

Related Questions

Why does my AC smell musty, sour, or burnt?What should I do if I smell gas by my heater?What if my carbon monoxide alarm sounds?How do I prepare my HVAC system for a North Texas cold snap?

Still Have Questions? Ask an HVAC Expert.

Couldn't find the answer you need? Tell us what's happening. Our team will review your question and contact you to help.

Ask Your Question →

Sources