How Often Should a Furnace Be Serviced?
If you've never thought much about furnace maintenance until the heat stopped working on a January night, you're not alone. Most homeowners don't think about their furnace at all — until something goes wrong. The good news is that one simple habit can prevent the majority of furnace breakdowns: annual professional service. Here's what that means, what it includes, and why skipping it costs more in the long run.
The Short Answer: Once a Year, Every Year
Furnaces should be professionally serviced once a year. That's the recommendation from heating equipment manufacturers, energy efficiency experts, and HVAC technicians alike. The U.S. Department of Energy specifically recommends annual professional inspections to keep gas and oil furnaces running safely and efficiently.
Think of it like a car oil change — you don't wait for the engine to knock before you service it. Routine maintenance is what keeps small, inexpensive issues from turning into major repairs.
Why Fall Is the Best Time for a Furnace Tune-Up
In Missouri, the ideal window for furnace service is September through October — before the heating season kicks in. Here's why timing matters:
- Availability: HVAC companies are easier to schedule in fall. Once cold weather hits and furnaces start failing across the area, wait times go up.
- Preparedness: You'll head into winter knowing your system has been inspected, cleaned, and tested — not just hoping it starts up okay.
- Safety lead time: If a technician finds a problem during a fall tune-up, you have time to get it repaired before temperatures drop.
That said, if your furnace hasn't been serviced and it's already December, don't wait until next fall. Get it done now.
What Counts as a Furnace Tune-Up?
A real tune-up is more than a visual check. When an AAA Home Services technician services your furnace, they go through a detailed inspection and cleaning that covers:
- Inspecting the heat exchanger for cracks (a cracked heat exchanger can allow carbon monoxide into your living space)
- Cleaning the burners and checking flame characteristics
- Testing gas pressure and checking for leaks
- Lubricating moving parts in the blower motor and fan
- Checking and tightening electrical connections
- Testing the thermostat and safety controls
- Inspecting the flue and venting for blockages or damage
- Measuring system efficiency and airflow
These aren't things you can do with a flashlight and a YouTube video. They require trained technicians and proper equipment.
What You Should Do Between Annual Service Visits
Professional service is annual, but there are things you should check more frequently:
Replace your air filter every 1–3 months. A clogged filter is one of the most common causes of furnace problems. It restricts airflow, makes the system work harder, and can cause overheating. If you have pets or multiple people in the home, check it monthly.
Keep vents and registers clear. Don't block return air vents with furniture. Blocked airflow strains your system.
Listen for unusual sounds. Banging, rattling, or high-pitched squealing are signs something has changed. Don't ignore them.
Check your carbon monoxide detector. Every home with a gas furnace should have working CO detectors. Test them monthly and replace batteries annually.
What Happens If You Skip Annual Service?
Skipping a year here and there might seem harmless, but the effects add up:
- Higher energy bills: A dirty, poorly tuned furnace uses more fuel to produce the same heat.
- Shortened lifespan: Furnaces that aren't maintained typically fail years earlier than those that are serviced regularly.
- Undetected safety hazards: Heat exchanger cracks and gas leaks don't announce themselves. A technician might catch something during a routine visit that you'd never notice until it became an emergency.
- Warranty issues: Many furnace manufacturers require proof of annual maintenance to honor warranty claims.
Our furnace repair team responds to emergency calls all winter — and a surprising number of those calls are for systems that hadn't been serviced in years. The repair cost almost always exceeds what annual tune-ups would have cost over the same period.
How to Schedule Furnace Service in St. Charles or St. Louis
AAA Home Services has been keeping furnaces running in St. Charles, St. Louis, Lincoln and Warren Counties since 1970. Our technicians do not work on commission, which means they're focused on what's actually best for your system — not on selling you parts or services you don't need.
To schedule your annual furnace tune-up, call us at (636) 397-3200 or request service online. Fall appointments fill up fast, so don't wait until the first cold snap to call. You can also learn more about our full range of heating and cooling services.
