Turning the Heat On for the First Time: A Fall Checklist

By Ray Bennett · Updated 2 October 2026 · 5 min read · Checked against the sources at the end

Turning the Heat On for the First Time: A Fall Checklist

Short answer

Book the heating check-up in the fall: ENERGY STAR says contractors get busy once winter comes. Check the filter, and Trane says change it more often while the heating runs longer. Clear furniture and curtains off the vents, check the thermostat, and put carbon monoxide alarms on every level, as the CPSC advises. A dusty smell on the first run is common.

A furnace or heat pump that sat idle all summer shows its faults on the first cold night, which is also the night every heating company is busiest. A little checking a few weeks earlier moves most of those faults to a day when they are easy to fix.

This checklist comes from ENERGY STAR’s maintenance checklist, Trane’s winter preparation advice and owner’s guide, and the U.S. Consumer Product Safety Commission.

Before you start

What to carry: a torch and a new filter of the right size. Fifteen minutes.

Gas or electric? Both, with more to check on gas. ENERGY STAR’s heating check-up covers the gas or oil connections, the gas pressure, the burner and the heat exchanger. An electric heat pump needs its outdoor unit kept clear.

Pick a mild day. Run the heating once before you need it, so a fault turns up while you still have time.

Three things that mean stop. Rotten eggs. That is the warning smell added to gas. Leave the house and call from outside: what each furnace smell means.

A carbon monoxide alarm. The CPSC says get everyone outside, call 911, and do not go back in until the responders say so.

Burning plastic or a hot electrical smell. Switch the furnace off at its switch and the breaker, and find out why.

Book the check-up early

The fall checklist in order. The first job is the one that fills up fastest: the contractor's calendar.

Check 1

Get the heating checked in the fall

When. ENERGY STAR recommends a pre-season check-up every year, the heating in the fall, because contractors get busy once winter comes. It suggests tying it to the clock change.

What it covers on gas or oil. ENERGY STAR lists the gas or oil connections, the gas pressure, the burner combustion and the heat exchanger. It says a dirty burner or a cracked heat exchanger makes the equipment run less safely.

The chimney and flue. The CPSC says the yearly inspection should check chimneys and flues for blockages, corrosion and loose or broken connections.

Everything else. ENERGY STAR adds the thermostat settings, the electrical connections, the moving parts, and a check that the system starts, runs and shuts off properly: how often to service it.

The filter

Check 2

Fit a clean filter

Monthly. ENERGY STAR says to inspect, clean or change the filter once a month, because a dirty one raises energy costs and can damage the equipment.

More often in winter. Trane says the heating runs more often and longer in the cold, so change filters more frequently. Its owner’s guide says the same size and type as the original.

The right way round. Trane says to fit it with the arrows pointing in the direction of the airflow: which way the filter goes.

Vents, thermostat and the first run

Check 3Free, fifteen minutes

Run it once and watch

The vents. Trane says to move furniture and curtains away from the registers, because blocked vents stop warm air circulating and put stress on the system.

The thermostat. Trane says to check it is working. Switch it to Heat, set it a few degrees above the room, and fit fresh batteries if it takes them.

The first smell. Dust that settled over the summer burns off on the first run, and a hot dusty smell for a while is common: when a smell is normal and when it is not.

Nothing happens. Trane’s owner’s guide checks the main switch is on, the breaker or fuses, and the thermostat setting: a furnace that will not work.

Carbon monoxide alarms

The CPSC's rules for carbon monoxide alarms, worth checking before the heating season starts.

Check 4The price of an alarm

Check the alarms

Every level. The CPSC says to put alarms on every level of the home and outside sleeping areas, battery powered or with battery backup. Interconnected alarms are best.

The standard. The CPSC says to use alarms that meet UL 2034.

The test button. The CPSC says it checks the circuitry, not the sensor, and alarms have a replacement age.

If one sounds. The steps are here, and they start with getting out: a carbon monoxide alarm going off.

Heat pumps, and an empty house

Check 5

Keep it clear, keep the pipes warm

The outdoor unit. Trane’s owner’s guide says to keep it clear of snow, ice and debris, with nothing stacked against it or draped over it. Trane’s winter advice adds: never a solid cover on a heat pump: covering the outdoor unit.

The blue light. Trane’s owner’s guide says that as the outdoor temperature falls, an auxiliary heat light that comes on now and then is normal.

Away for the winter. Trane’s owner’s guide says that if the heating will not run in cold months, you must protect the water pipes from freezing, especially in an empty house: frozen pipes.

Questions people ask

When should I have my furnace checked?

In the fall, before the cold. ENERGY STAR says contractors get busy once winter comes, and suggests tying the check-up to the clock change.

Why does my furnace smell when I turn it on for the first time?

Dust that settled over the summer burns off. A hot dusty smell for a while is common. Rotten eggs or exhaust is not: leave and call from outside.

How often should I change the filter in winter?

ENERGY STAR says check it monthly. Trane says change it more often in winter, because the heating runs more and for longer.

Do I need carbon monoxide alarms?

The CPSC recommends them: on every level and outside sleeping areas, meeting UL 2034, with battery power or backup.

Should I test the heating before it gets cold?

Yes. Run it once on a mild day, so any fault turns up while contractors still have time to come.

What if I am away all winter?

Trane’s owner’s guide says to protect the water pipes from freezing if the heating will not run, especially in an empty house.

Sources: The ENERGY STAR Maintenance Checklist, Trane "Extreme Winter Weather Preparation for Your Home and HVAC" and its Owner's Guide 22-5213-WEB01, and the CPSC "Carbon Monoxide Questions and Answers"