Prepare Your Heating System for Winter

The single highest-value step: run your heating system for a full cycle before the first cold snap. Switch the thermostat to HEAT, set it a few degrees above room temperature, and let it run 15–20 minutes. Listen for unusual banging, squealing, or rumbling, check that warm air comes from the vents, and confirm it cycles off when the setpoint is reached.

A dusty burning smell on the first run of the season is normal — it is dust burning off the heat exchanger and elements — and should fade within an hour. A persistent burning smell, or any smell of gas, is not normal: for gas odors, leave the house and call your gas utility or emergency services from outside.

Start the heating season with a fresh air filter — a clogged filter is the most common cause of poor heating performance and can overheat a furnace by restricting airflow. Walk the house and open every supply vent; closing vents in unused rooms does not save energy the way people think, and it raises system pressure and reduces efficiency.

Make sure return grilles are unblocked by furniture, rugs, and curtains, and clear the area around the furnace or air handler itself — no storage boxes, paint cans, or clutter against the unit. Combustion appliances need clear space and combustion air; crowding them is both a performance and a safety issue.

For gas furnaces, check that the flue and vent pipes are clear and undamaged — birds and debris love to nest in them over summer, and a blocked flue can push combustion gases back into the home. Look at the burner flames through the sight glass if your furnace has one: they should burn steady and blue. Yellow, flickering, or lazy flames warrant a professional look.

Note the age and service history of the unit. If it has not been professionally serviced in more than a year, fall is the time — heat exchangers develop cracks with age, and a cracked heat exchanger can leak carbon monoxide. This is the inspection that matters most for gas heating safety.

Heat pump owners: clear leaves and debris from around the outdoor unit, gently rinse the coil, and make sure nothing blocks airflow within a couple of feet. Know where your auxiliary or emergency heat setting is on the thermostat — auxiliary heat engaging constantly in mild weather signals a problem, while emergency heat is a manual backup mode for when the heat pump itself cannot run.

Expect the outdoor unit to frost up and run defrost cycles in cold weather — steam rising from the unit during defrost is normal. What is not normal: the unit encased in ice that never clears, or the system running auxiliary heat all winter in moderate cold. Both deserve a technician's attention before the deep cold arrives.

Heating season is detector season. Test every smoke and carbon monoxide detector, replace batteries, and check manufacture dates — detectors expire, typically after about a decade. Every home with gas appliances or an attached garage needs working CO detectors on each level, especially near sleeping areas.

Know where your gas shutoff valve is and how it operates before you need that knowledge in a hurry, and make sure everyone in the household old enough to act knows too. Keep the furnace area clear of flammables, and never store gasoline, solvents, or aerosols near combustion appliances.

Annual professional maintenance in fall is the standard recommendation for heating equipment, and it is genuinely worthwhile: a technician cleans and inspects the heat exchanger, checks gas pressure and ignition, tests safety controls and CO levels, verifies airflow, and catches the worn parts that fail on the coldest night of the year.

Book early in the season — HVAC companies get slammed with no-heat calls during the first real cold snap, and maintenance appointments scheduled in early fall get better availability and unhurried technicians. If your system is aging or has needed repairs two seasons running, ask the technician for an honest assessment of remaining life so a replacement can be planned, not panicked.