Furnace won't start
Thermostat calls for heat but nothing happens — usually an igniter, thermocouple, or control board issue. Most are same-day repairs.
Gas Furnace Repair
Gas Furnace Repair in Sumter, SC
When your gas furnace stops working, restoring heat is only part of the job. Every gas furnace repair starts with verifying the safe operation of the entire system, including combustion, gas pressure, and heat exchanger integrity.
Our licensed technicians diagnose the actual problem, explain your options clearly, and get your heat back on safely.
Safety First. Then the Repair.
See how we approach every call →
Every furnace call starts with combustion analysis.
Unlike many HVAC repairs, gas furnace service involves testing the combustion process itself. Our technicians verify gas pressure, inspect the heat exchanger, test for carbon monoxide, and confirm that exhaust gases are venting safely through the flue before the repair is considered complete. It’s a more thorough process because it protects both your heating system and your family.
We hold the South Carolina State Mechanical License required for gas piping work, and our technicians are trained to perform combustion analysis, inspect heat exchangers, and verify carbon monoxide levels as part of every furnace service call. You’ll receive the repair price in writing before any work begins, and if a repair doesn’t hold, we’ll return to make it right at no additional charge.
Common Furnace Calls
Six furnace problems that need a licensed tech.
Some are quick fixes. Some are safety calls. Know the difference.
Short-cycling
Runs for 60–90 seconds then shuts off and repeats. Often a dirty flame sensor, a tripped limit switch, or an airflow restriction causing overheat.
Furnace blower won't stop running
Furnace cycles complete but the blower keeps pushing cold air. Usually a faulty fan limit switch or a thermostat wiring issue.
Yellow or flickering flame
A healthy burner flame is steady blue. Yellow or flickering means incomplete combustion — a combustion analysis call, not a “wait and see.”
Loud boom on startup
Delayed ignition — gas accumulates briefly before lighting. The boom is the accumulated gas catching at once. Not normal; can crack heat exchangers over time.
Gas smell, CO alarm, or soot
Stop running the furnace immediately. Shut off at the gas valve, get everyone outside, and call us from outside. These are emergencies.
No heat or a safety concern? Call (803) 481-8200 now — we dispatch 24/7.
Our Process
What to Expect During Your Gas Furnace Repair
Every gas furnace repair follows the same safety-first process, from combustion testing to final system verification.
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Same-day scheduling
Call or request online. Same-day on most weekday calls; faster on no-heat emergencies.
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Safety check first
CO ambient reading, combustion analysis, gas-pressure verification, heat exchanger inspection — before we name the part.
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Written options
Repair price, alternatives, and recommendation in writing — with safety implications spelled out plainly.
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Repair + verification
Most furnace repairs wrap same day. Combustion zone resealed, electrical connections re-torqued, system run through a full heat cycle.
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Post-repair combustion check
Before we leave, we re-run combustion analysis, confirm CO levels are normal, and document the readings for your file.
Why homeowners trust Advance for gas furnace repair
Safety first, then the repair. Every time.
- NATE-certified technicians trained specifically in gas combustion diagnostics
- SC State Mechanical License — required for gas system work
- Heat exchanger inspection on every furnace call — not optional, not an upsell
- Combustion analysis and CO verification before and after every repair
- Repair price in writing before any work starts
- 24/7 emergency dispatch — live answering at (803) 481-8200
Repair or replace? How to think about it.
Honest math, not a push toward the bigger ticket.
- Under 12 years old, fix under $700 — repair almost always makes sense
- 12–15 years old — weigh repair cost vs. current efficiency and remaining life
- 15+ years old — if fix exceeds ⅓ of replacement cost, replacement usually wins
- Cracked heat exchanger — there’s no safe repair; only replacement resolves it
- More than $1,200 in repairs in 12 months — pattern matters more than any single fix
- We show you the math — payback period, efficiency gain, financing options
Frequently Asked
Furnace repair questions, answered straight.
When should I shut the furnace down and call immediately?
If you smell gas, if your CO detector alarms, if you see a yellow or orange flame instead of steady blue, or if you notice soot around the burner area — shut off the furnace at the gas valve, get everyone out of the house, and call us from outside. These are not “schedule a visit” situations.
How much do furnace repairs cost?
Most furnace repairs in our area land between $200 and $700. Flame sensors, thermocouples, and igniters usually run under $400 installed. Blower motors, gas valves, and control boards typically $500–$900. Heat exchanger replacement is priced at full system replacement because the part alone often costs more than a new furnace.
Should I repair or replace my furnace?
Repair almost always makes sense if the furnace is under 12 years old and the fix is under $700. Replace usually makes sense if it’s 15+ years old, has a cracked heat exchanger, or has cost more than $1,200 in repairs over the past 12 months. We’ll show you the math, not just a recommendation.
What is a heat exchanger and why does it matter?
The heat exchanger is a metal chamber that separates the burner flame from the air blown into your house. A crack means combustion gases — including carbon monoxide — can leak into the air your family breathes. There’s no safe repair for a cracked heat exchanger; the only safe path is replacement. On most furnaces over 12–15 years old, a cracked exchanger means replacing the whole furnace.
Do you inspect the heat exchanger on every visit?
Yes. Heat exchanger inspection is part of every furnace service call — it’s not optional, and it’s not an upsell. We check it on repairs, on maintenance visits, and on any call where combustion behavior looks unusual.
How long does a furnace repair usually take?
Many common gas furnace repairs can be completed during the same visit once the problem has been diagnosed. If specialty parts are needed or a heat exchanger issue is discovered, we’ll explain the repair timeline and provide written pricing before any work begins.
Is furnace repair safe to attempt as a DIY project?
No. Furnace work involves an active gas line, combustion under pressure, a flue moving exhaust gases out of your living space, and a heat exchanger that can put carbon monoxide into the air. Each of these requires diagnostic equipment and training to evaluate correctly. The consequences of getting it wrong are serious.
Why is my furnace blowing cold air?
A furnace may blow cold air because of a dirty flame sensor, faulty igniter, thermostat issue, overheating safety switch, or problems with the gas supply. Our technicians perform a complete diagnostic to identify the cause before recommending a repair.
Why won’t my furnace turn on?
If your furnace won’t start, the issue could be a tripped breaker, thermostat problem, failed igniter, dirty flame sensor, faulty control board, or gas supply interruption. Some problems are simple fixes, while others require professional diagnosis to restore safe operation.
Financing & Payment Options
Flexible Financing for Repairs, Replacements & New Systems
HVAC investments shouldn't put your comfort on hold. We work with qualifying customers to spread the cost of repairs, replacements, and indoor air quality upgrades into manageable monthly payments.
Repair or replace — financing available either way. If the repair is approaching replacement territory, financing lets you make the right long-term decision without the full up-front cost.
Subject to credit approval. Financing options, terms, and qualifications may vary by lender and project type. Not all applicants will qualify. Our team can walk you through available options when you request service or an estimate.
Heat restored
Safety verified. Problem fixed.
Combustion analysis on every call. Heat exchanger inspection included. Repair price in writing before any work starts. Live answering 24/7.