Why won't my furnace ignite?

The two most common causes are a dirty flame sensor (it can't confirm the burner lit, so the furnace shuts down for safety) and a cracked hot-surface igniter. Both are inexpensive parts. A good tech rules these out before quoting a control board or condemning the furnace.

How much should an igniter or flame sensor cost?

The parts are inexpensive; the service call and labor make up most of the bill. An honest shop prices the specific failed part directly rather than bundling it into a vague 'ignition system' quote or using it to upsell a replacement.

When is the busiest season for furnace repair in Knoxville and how should I schedule service before a cold snap?

Late fall into winter is the busiest season because cold snaps trigger ignition and no-heat calls. Schedule inspections or tune-ups in early fall to avoid peak demand. Prioritize contractors who list emergency service availability and offer scheduled pre-season visits. In neighborhoods like Downtown and Old North Knoxville, earlier scheduling is common due to older housing stock.

What signs indicate an igniter or flame sensor issue specific to Knoxville homes?

Repeated ignition failure, delayed ignition, or the furnace cycling off shortly after start suggest igniter or flame sensor problems. In Knoxville, moisture and cycling from cold snaps increase these failures. A technician should test the control sequence, inspect the sensor alignment, and check for corrosion or moisture-related faults before recommending replacement.

When should a Knoxville furnace heat exchanger be inspected for corrosion or cracks after repeated short‑cycling?

Inspect the heat exchanger promptly after repeated short‑cycling or unexplained pressure changes. Short‑cycling increases thermal stress and can reveal hairline cracks or corrosion. A qualified technician should perform a visual and combustion‑analysis inspection and recommend containment or replacement if the exchanger fails safety checks.

How do I get a quote from these furnace repair companies?

Submit one request on this page and we send it to the vetted furnace repair pros in Knoxville, TN listed here. They send quotes back — no obligation.

Best Furnace Igniter & Flame Sensor Repair in Knoxville, TN

Last updated July 8, 2026

What to look for in Igniter & Flame Sensor Repair in Knoxville

A fouled flame sensor or cracked hot-surface igniter is the most common reason a furnace stops heating — and the cheapest fix when diagnosed honestly. We weight providers who rule out the common, low-cost parts before quoting a control board or a new furnace.

Common-failure-first diagnosis. Provider lists igniter and flame-sensor repair as distinct service lines and states it isolates the failed part before quoting major components.
Combustion / method evidence. Stated combustion or measured diagnosis corroborates that the shop tests rather than guesses.
Google rating. A strong rating floor is the minimum trust threshold for a common repair.

Verify before you book

Whether the cheap parts were actually ruled out first — ask which component tested bad.
The flat-rate price for your specific furnace model — confirm before authorizing.
License status with your state board — verify TDLR (TX), ROC (AZ), or your local equivalent before paying.

See full ranking methodology for Igniter & Flame Sensor Repair →

Furnace Igniter Repair in Knoxville: what fails first

The flame sensor and hot-surface igniter are the high-frequency, low-cost no-heat failures — ruling them out first tells an honest shop apart from one that jumps to a control board or a new furnace. Here is what each of the 1 pro below publishes: Verify your state's HVAC contractor license through the state licensing board before paying a deposit.

How we rank Igniter & Flame Sensor Repair providers → · Top picks meet at least one of: a category award, ≥2 verified signals, or Vouched Score ≥ 70.

Top picks

Pioneer Heating, Cooling, Plumbing and Electrical★ Best for Igniter & Flame-Sensor Repair
Consistently strong customer feedback (4.8★ from 5,035+ Google reviews).
Google 4.8★ (5,035+)

Typical Igniter & Flame Sensor Repair costs in Knoxville, TN (2026)

Last updated June 21, 2026

Estimated ranges for Knoxville, TN. Actual cost varies with home size, equipment, and scope — always request a written quote for your job.

Service	Typical range
Flame sensor cleaning / replacement	$65–$205
Hot surface igniter replacement (installed)	$125–$370
Limit or pressure switch replacement (installed)	$125–$330

Why Knoxville, Tennessee winters make Furnace Repair different

Knoxville, Tennessee winters bring frequent cold snaps and humidity swings that strain older furnaces and ductwork in many downtown brick bungalows and midcentury homes. Homeowners searching for the best furnace repair companies in Knoxville, TN should prioritize licensed furnace repair contractors who offer emergency service, clear pricing, and parts warranties.

What Knoxville-specific questions do homeowners ask about Furnace Repair?

Why won't my furnace ignite?: The two most common causes are a dirty flame sensor (it can't confirm the burner lit, so the furnace shuts down for safety) and a cracked hot-surface igniter. Both are inexpensive parts. A good tech rules these out before quoting a control board or condemning the furnace.
How much should an igniter or flame sensor cost?: The parts are inexpensive; the service call and labor make up most of the bill. An honest shop prices the specific failed part directly rather than bundling it into a vague 'ignition system' quote or using it to upsell a replacement.
When is the busiest season for furnace repair in Knoxville and how should I schedule service before a cold snap?: Late fall into winter is the busiest season because cold snaps trigger ignition and no-heat calls. Schedule inspections or tune-ups in early fall to avoid peak demand. Prioritize contractors who list emergency service availability and offer scheduled pre-season visits. In neighborhoods like Downtown and Old North Knoxville, earlier scheduling is common due to older housing stock.
What signs indicate an igniter or flame sensor issue specific to Knoxville homes?: Repeated ignition failure, delayed ignition, or the furnace cycling off shortly after start suggest igniter or flame sensor problems. In Knoxville, moisture and cycling from cold snaps increase these failures. A technician should test the control sequence, inspect the sensor alignment, and check for corrosion or moisture-related faults before recommending replacement.
When should a Knoxville furnace heat exchanger be inspected for corrosion or cracks after repeated short‑cycling?: Inspect the heat exchanger promptly after repeated short‑cycling or unexplained pressure changes. Short‑cycling increases thermal stress and can reveal hairline cracks or corrosion. A qualified technician should perform a visual and combustion‑analysis inspection and recommend containment or replacement if the exchanger fails safety checks.
How do I get a quote from these furnace repair companies?: Submit one request on this page and we send it to the vetted furnace repair pros in Knoxville, TN listed here. They send quotes back — no obligation.