Furnace Maintenance in St. Louis, MO

A furnace tune-up is a scheduled inspection of every part that has to work for your furnace to heat safely, and it is the cheapest time to find a problem. The U.S. Department of Energy's home energy checklist says to have a furnace or heat pump professionally maintained each year. EPA adds that any fuel-burning furnace should be serviced before each heating season to prevent carbon monoxide poisoning.

What does a furnace maintenance visit include?

A visit covers nine checks, and each one produces a result you can ask to see.

• Thermostat call for heat. The furnace starts when the thermostat asks and shuts off when the house is warm.
• Filter and blower. We inspect the filter, check the blower motor and capacitor, and clean the blower wheel if dust has built up.
• Igniter and flame sensor. The igniter is tested, and the flame sensor rod is cleaned, because a film on it is a common reason a furnace starts and then quits.
• Burners. Flame color and pattern tell us whether combustion is clean.
• Heat exchanger. A visual and camera check for cracks, rust and soot, where access allows.
• Flue and venting. Pipes and joints are checked for blockage, sagging and signs of backdrafting.
• Gas connections. Visible fittings are checked for leaks.
• Safety switches and condensate drain. Limit and rollout switches are tested, and a high-efficiency furnace gets its drain traced.
• Carbon monoxide reading. Taken at the flue while the burners run.

You get the findings in plain language. Any repair is priced separately, and you see the number before work begins.

How does a tune-up visit run?

1. Confirm the symptoms and the furnace's history.
2. Test the call for heat and the start-up sequence.
3. Clean and test the igniter, flame sensor and burners.
4. Inspect the heat exchanger, flue and gas connections.
5. Test the safety switches and take the carbon monoxide reading.
6. Explain the findings and quote any repair before starting it.

When should you book furnace maintenance in the St. Louis area?

Book between late August and early October, before the first cold snap. St. Louis sits in ASHRAE Climate Zone 4A, and the National Weather Service recorded 4,100 heating degree days in 2025 against a normal of 4,433. Even a mild winter asks a furnace to run for months.

Waiting for the first freeze means a failed part meets a 10-degree night. Age matters too. Contractor sources put furnace life at about 15 to 20 years with routine care, and a tune-up on an older unit shows how much life is left before you spend on furnace replacement.

Which signs mean a check cannot wait for fall?

Book now if you see black stains on the outside of a chimney or flue, vent pipes that are loose or disconnected, or burners that start and quit. CPSC says stains and loose vents can mean pollutants are leaking into the house, and lists headache, fatigue, nausea and dizziness as carbon monoxide symptoms.

What does maintenance prevent, and what does it leave alone?

Maintenance prevents the slow failures: a dirty sensor, a clogged vent, a worn motor, a gas fitting that has started to weep. It also gives a technician a look at the heat exchanger, the part that separates combustion gases from the air your family breathes.

It does not repair or rebuild anything. These are outside a standard visit:

• Parts and repairs, quoted separately after the findings. See furnace repair for how diagnosis works.
• Duct cleaning, which EPA does not recommend as routine. Our air duct cleaning page explains when it is worth buying.
• Humidifier pads, whole-house filters and thermostat replacement unless you ask.

A tune-up also cannot make an old furnace young. If the heat exchanger is cracked, we say so and explain the options.

Does a tune-up need a permit or a license?

St. Louis County lists installing, altering, repairing and replacing heating systems as permit work, and says filter changes and refrigerant recharges are not. We found no county or city page treating an inspection and cleaning alone as permit work. A repair found during the visit may be, so ask who applies. County mechanical licensing answers at (314) 615-7096, and the City of St. Louis requires a City-licensed contractor for replacement units.

What should you do yourself before the visit?

Do five small jobs, none of which needs tools. They also make the visit faster.

• Replace the filter. EPA says to use MERV 13 or the highest rating your system can handle, and to replace it about every 60 to 90 days.
• Clear three feet around the furnace and keep registers open.
• Check that outdoor vent and intake pipes are free of leaves, snow and nests.
• Test carbon monoxide alarms. The Consumer Product Safety Commission says to place them on every level and outside sleeping areas.
• Write down symptoms: odd noises, short cycles, rooms that run cold.

If you ever smell gas, leave first. Do not touch switches or flames. Call 911 or Spire's St. Louis emergency line at 800-887-4173 from outside.

What affects the price of a furnace tune-up?

Price depends on the furnace, the access and the condition it is in. Angi reports St. Louis HVAC labor at about $75 to $150 per hour in 2026, which is a market figure and not our quote.

• Furnace type: a standard 80 percent unit and a condensing unit with drain and intake piping take different time.
• Access: an attic or crawl space adds labor.
• Condition: a blower wheel packed with dust takes longer to clean.
• Scope: a filter swap and a glance is not a combustion and heat exchanger inspection.

Ask any company for the visit's scope in writing. We give a clear, upfront quote before work starts. A camera look and a combustion reading take more time than a filter swap, and at Angi's labor range, time is most of the price.

Why Kenan Corporation for a furnace check

The proof sits in what customers wrote on Google, where Kenan Corporation holds 4.6★ from 29 reviews as of October 2026.

• Gas-side follow-through. Frederick E. wrote that after a gas inspection the leaks were found and fixed, the pressure was tested, and the work passed Spire's reinspection.
• Parts tested, not guessed. Wendy R. was told by another company that a new furnace was needed. The real fault was a capacitor.
• Open 24 hours. If a part fails after the visit, the same number answers in January.
• Founded on fairness. Kenan Bruce Martz started the company in 2010 after 20-plus years at St. Louis area HVAC companies, disliking the hard-sell pitches and commission goals he saw in the trade.

Missouri has no statewide HVAC license. Ask any company, ours included, for the license number the City of St. Louis or St. Louis County issued.

Where do you do furnace checks near Spanish Lake?

Furnaces installed 15 to 20 years ago in postwar homes are at the age where a yearly check earns its keep. Minutes are from our Broadhead Lane base in normal traffic.

• Spanish Lake, about 5 minutes: basement gas furnaces in ranch homes, a few minutes from the shop.
• Ferguson, about 20 minutes: a 1957 median build year, and old boiler chimneys that get a venting check.
• Florissant, about 20 minutes: 18,000 houses built from 1947 to 1980, so yearly records show each furnace's condition.
• Jennings, about 20 minutes: 55 percent of homes are rented, so findings come in plain language for a landlord.
• Hazelwood, about 25 minutes: 1960s ranches with closet furnaces, where clearance is checked.
• Bridgeton, about 30 minutes: damp low ground near the river levee puts the condensate drain under watch.
• Webster Groves, about 40 minutes: say whether heat comes from radiators or registers.
• Kirkwood, about 50 minutes: houses built before air conditioning have tight utility space.
• Ballwin, about 55 minutes: furnaces tucked between floors in 1970s split-levels leave little room.