Heating in St. Louis, MO

Heating in St. Louis falls into three families, and the one you own decides what repairs cost and what replacement looks like. Gas furnaces dominate, heat pumps are growing, and the older brick housing stock still leans on boilers and radiators. NWS St. Louis counted 4,100 heating degree days in 2025, against a 4,433 normal, so even a mild winter asks a lot of the equipment.

Which heating system do you have, and what does that change?

Start by identifying the equipment, because each type fails differently.

• Gas furnace. Blows heated air through ducts. Common faults are ignition, a failed capacitor or blower motor, and a dirty flame sensor. See furnace repair and furnace maintenance.
• Heat pump. Moves heat in both directions with one outdoor unit. Frozen coils and weak heat point to defrost or airflow trouble. See heat pump repair.
• Boiler with radiators. Heats water and sends it through pipes. Leaks, air in the lines and cold radiators are the usual signs. See boiler service.

If you smell gas, leave the house before doing anything else. Touch no switches and light nothing. From outside, call 911 or Spire's St. Louis emergency line at 800-887-4173. Spire says it does not charge to investigate a gas smell. When the utility clears the house, call us about the furnace.

Should you repair the furnace or replace it?

Repair when the failed part is small and the furnace is sound, and replace when repairs keep coming on equipment near 15-20 years. The federal gas furnace minimum is 80 AFUE, so ask any quote to show the AFUE of the unit it prices and compare it with your current one.

A Google reviewer wrote that another company said a new furnace was needed because the heat would not come on, and Kenan Corporation found a capacitor and fixed it. That pattern is why we diagnose before replacing parts. When replacement does fit, furnace replacement and furnace installation cover sizing and the permit steps.

Does a heat pump make sense in a St. Louis home?

Sometimes, and the quote should prove it with a load calculation. Homeyou reports heat pump installs in the St. Louis area at $5,300-$6,971 on average across 332 projects (2025), and that is a market figure, not our quote. Ameren Missouri's 2026 chart, valid January 1 to December 31, 2026, lists $2,000 per system for qualifying air-source models at 15.2+ SEER2. Confirm eligibility in writing before you sign.

Read heat pump installation for the sizing and cold-weather questions to ask, and compare it with a furnace and AC pair before you decide.

What should an older brick home do about heat?

Inspect first. Census figures put the middle of the City's housing stock at 1938 construction (ACS via Neilsberg), and boilers, radiators and narrow chases are common in homes that old. Ducts in plaster walls mean opening them, so keeping a healthy boiler can be the cheaper path, while a ductless mini-split can add cooling without opening them. Whichever path fits, the permit and the inspection belong in the written quote.