Furnace London Ontario
Complete Guide
Everything a London Ontario homeowner needs to know about gas furnaces — how the four-stage combustion cycle works, the difference between single-stage, two-stage, and modulating units, how long a furnace lasts in London Ontario's climate, the 8 signs it needs replacing, why natural gas is the right fuel for most Southwestern Ontario homes, and what every component does when something goes wrong. Gas furnace installation from $3,400. Enbridge $650 rebate handled. $175 diagnostic. 24/7 zero surcharge. TSSA certified. BBB A+. 138 five-star reviews.
Furnace Repair, Installation & Maintenance — London Ontario
Whether your furnace needs repair, replacement, or annual maintenance — published pricing, 24/7 emergency, and TSSA certified service throughout Southwestern Ontario.
Furnace Repair
Applied to repair cost. Written repair vs replace recommendation. 24/7 emergency zero surcharge. Igniter, flame sensor, inducer, control board, gas valve, heat exchanger assessment.
Repair Details ›Furnace Installation
Goodman or Midea from $3,400. Carrier or Lennox from $4,200. 96% AFUE. Enbridge $650 rebate handled. Old furnace removed. Permit and gas inspection included. No rental.
Installation Details ›Annual Maintenance
12-point inspection, combustion analysis, CO test, flame sensor cleaning, flue inspection, thermostat check. Premium $249/yr with priority dispatch. No monthly subscription.
Maintenance Details ›How a Gas Furnace Works — The Four Stages
Understanding the combustion cycle helps you understand what each component does — and what it means when something goes wrong. Every gas furnace in London Ontario follows the same four-stage sequence every time it fires.
Thermostat Calls for Heat
The thermostat detects that room temperature has dropped below the setpoint and sends a 24-volt signal to the furnace control board. The control board starts the safety sequence before allowing any gas to open.
Inducer Motor Creates Draft
The inducer motor starts and purges any residual gas from the heat exchanger and confirms the flue is clear. The pressure switch measures the negative pressure created by the inducer — only when it confirms proper draft does the control board allow ignition to proceed. This prevents combustion gas back-draft into the home.
Ignition and Flame Confirmation
The hot surface igniter heats to approximately 900°C. The gas valve opens and delivers gas to the burner. Gas ignites on the igniter. The flame sensor rod, positioned in the flame, generates a small electrical current that confirms combustion — keeping the gas valve open. If the flame sensor cannot confirm flame, the gas valve closes within seconds as a safety measure.
Heat Exchange and Air Distribution
Combustion occurs inside the sealed heat exchanger. The heat exchanger walls absorb combustion heat. The blower motor starts and circulates return air from the home across the hot heat exchanger walls, picking up heat, and distributing warm air through supply ducts. Combustion gases — never touching the circulating air — exit through the flue or PVC direct-vent pipe. In a 96% AFUE condensing furnace, a secondary heat exchanger extracts additional latent heat from the cooling flue gases before they exit.
Why the heat exchanger matters so much: Stage 4 is where the heat exchanger does its job — transferring combustion heat to circulating air while keeping combustion gases completely separated. A crack in the heat exchanger breaks this separation and allows carbon monoxide to enter the living space. This is why annual combustion analysis (measuring CO in circulating air) is the primary safety purpose of annual furnace maintenance — and why a confirmed cracked heat exchanger requires immediate furnace replacement.
Furnace Types — Single-Stage, Two-Stage & Modulating
The three types differ in how many output levels they have — which affects comfort, efficiency, and noise. For most London Ontario homes, two-stage is the sweet spot.
Single-Stage Furnace
- One output level: 100% capacity always
- Fires at full blast, reaches setpoint, shuts off
- Short-cycles in milder weather (October, March)
- More temperature swings — noticeable blasts of heat
- Simpler, fewer components, lower initial cost
- Good for smaller or tightly zoned London homes
Two-Stage Furnace
- Two output levels: typically 65% and 100%
- Runs at low stage (65%) in mild weather for longer, quieter cycles
- Switches to 100% only when demand requires it
- More even temperatures throughout the home
- Better efficiency in real London Ontario conditions
- Goodman and Carrier models from $3,400–$4,200
Modulating Furnace
- Adjusts output continuously: ~40% to 100%
- Most precise temperature control — within 0.5°C
- Quietest operation — often inaudible at low fire
- Highest real-world efficiency in variable conditions
- Carrier Infinity Greenspeed, Lennox variable-capacity
- Higher initial cost — longer payback period
Honest recommendation for most London Ontario homes: For a 1,400 to 2,000 square foot post-2000 build — which describes the majority of London Ontario family homes — a two-stage Goodman at $3,400 installed provides comfort and efficiency that is indistinguishable from a modulating Lennox at $4,200+ for most households. Holm K.'s review below illustrates exactly this scenario — honest advice over a higher-margin recommendation.
Furnace Lifespan in London Ontario — What to Expect
Expected Furnace Lifespan — London Ontario
What Shortens Furnace Life
The three biggest factors that shorten furnace life in London Ontario: (1) Skipping annual maintenance — flame sensor oxidation, heat exchanger stress from combustion byproducts, and venting blockages all accelerate wear when left unchecked. (2) Oversizing — a furnace that is too large for the home short-cycles (fires and shuts off frequently), which puts more thermal stress on the heat exchanger than longer, lower-intensity cycles. (3) Running with a clogged filter — restricted airflow causes the heat exchanger to run hotter and the blower motor to work harder.
What Extends Furnace Life
Annual maintenance is the highest-value life-extension action. A $149 tune-up that catches early inducer motor bearing wear means a $400 repair done on your terms rather than a $600 emergency repair with no heat. Heat exchanger fatigue is the most common cause of furnace retirement — annual combustion analysis tracks deterioration so replacement can be planned rather than forced.
The 15-Year Decision Rule
Hawana's repair vs replace guidance: repair if the furnace is under 15 years old and the repair cost is under $1,700 (50% of a $3,400 new furnace). After 15 years, any significant repair triggers a replacement assessment — not because the furnace necessarily needs replacing, but because the economics of additional repair investment in an aging unit need to be compared against a new 96% AFUE furnace with a 20+ year life and the Enbridge $650 rebate. Hawana provides both quotes at every $175 diagnostic visit.
Do Harsh London Ontario Winters Shorten Life?
London Ontario's climate — cold but not extreme — does not significantly shorten furnace life compared to other Ontario cities. The design outdoor temperature of approximately -20°C means London furnaces run more hours per season than furnaces in milder climates, but Canadian-market furnaces are designed for these conditions. A correctly sized unit running 2,200 to 2,800 hours per heating season in London Ontario is within the normal design range.
Signs Your Furnace Needs Replacing — Not Just Repairing
Some signs call for a repair. Others call for immediate replacement. Here is how to tell the difference.
CO Detector Alarmed While Furnace Was Running
This is a safety emergency. Shut off the furnace, leave the home, call 911. A CO detector alarm while the furnace is running almost always indicates a cracked heat exchanger or a blocked flue. The furnace must be inspected before being restarted — and if a cracked heat exchanger is confirmed, replaced immediately.
Cracked Heat Exchanger Confirmed
A cracked heat exchanger allows combustion gases including carbon monoxide to enter circulating air. It cannot be safely repaired in most residential furnaces. Immediate replacement is required. Hawana condemns the unit in writing and provides a same-day replacement quote.
Over 15 Years Old with a Major Repair Needed
If the furnace is over 15 years old and requires a repair costing more than $1,000, replacement is usually the better investment. Remaining useful life does not justify the repair cost, and additional repairs are likely to follow.
Repair Cost Exceeds $1,700 (50% of New Furnace)
If a single repair would cost more than $1,700 — 50% of a $3,400 new furnace — the economics favour replacement at any age under 20 years. Hawana provides both quotes at the $175 diagnostic visit.
Gas Bills Have Increased Significantly Without Explanation
A furnace that has declined to 70% or lower efficiency — through heat exchanger cracks, burner fouling, or inducer wear — costs significantly more to operate. The Enbridge $650 rebate plus $200–$300 annual fuel savings can make replacement the financially correct decision on a furnace that is still technically running.
Two or More Major Repairs in the Past 3 Years
Multiple significant repairs on the same furnace within a few years indicates the unit is reaching the end of its service life. Component failures cluster as units age. The next repair is likely coming.
Cannot Maintain Setpoint on Coldest London Ontario Days
If the furnace runs continuously but cannot reach the thermostat setpoint when outdoor temperature is below -15°C, the unit may have declined in capacity or may have been undersized for the home. Replacement with a correctly sized unit resolves both issues.
Existing Unit Is 80% AFUE — Upgrade Makes Financial Sense
An 80% AFUE furnace that is still running but ageing can be a good candidate for proactive replacement. Upgrading to 96% AFUE saves $200–$300/yr in gas. The Enbridge $650 rebate applies. On a 10-year horizon, the upgrade typically pays back within 3–5 years even if the old unit has a few more years of life.
Gas Furnace Components — What Each Part Does & How It Fails
Every component a London Ontario homeowner should know when a technician is diagnosing their furnace.
Hot Surface Igniter
Heats to ~900°C to ignite the gas burner. When it cracks or burns out, the burner will not light. Most common furnace repair: $150–$250. Usually completed same visit as the diagnostic.
Flame Sensor
Metal rod in the burner flame that confirms combustion by generating a small current. Oxidation on the rod reduces current — causing the burner to light and shut off in seconds. Annual cleaning prevents failure. Repair: $150–$250.
Inducer Motor
Creates draft through the heat exchanger before ignition. Confirms flue is clear via the pressure switch. Grinding or rattling noise indicates bearing wear. Failure causes no-heat with no burner fire. Repair: $400–$600.
Pressure Switch
Monitors the draft created by the inducer. Only allows ignition when draft is confirmed. Failure (or a blocked condensate drain causing it to trip) prevents the burner from firing. Repair: $200–$350.
Heat Exchanger
The sealed metal component that transfers combustion heat to circulating air while keeping combustion gases separated. A crack allows CO to enter the home. Annual combustion analysis detects cracks early. Cracked exchanger = replace furnace.
Gas Valve
Controls gas flow to the burner. If the igniter glows and draft is confirmed but no gas reaches the burner, the gas valve has failed. Repair: $300–$500. On older units, replacement vs repair economics should be assessed.
Control Board
The furnace's central processor. Sequences the startup cycle, monitors safety controls, and displays error codes. Erratic operation or unresponsive furnace often indicates control board failure. Repair: $350–$600.
Blower Motor
Circulates air from the home across the heat exchanger and into supply ducts. If the furnace fires but no air comes from vents, or the high-limit trips repeatedly, blower motor failure is likely. Repair: $300–$500.
High-Limit Switch
Safety device that shuts off the gas valve if the air plenum overheats. Most commonly trips due to a clogged filter or blocked return air. Check the filter before calling for service — replacing a severely clogged filter often resolves a high-limit shutdown.
Furnace Fuel Types — Why Gas Is Right for Most London Ontario Homes
Over 85% of London Ontario homes use natural gas for space heating. Here is why, and when propane or electric alternatives make sense.
| Attribute | Natural Gas (Enbridge) | Propane | Electric Resistance | Heat Pump (Electric) |
|---|---|---|---|---|
| Availability in London ON | Universal (Enbridge grid) | Rural only (no pipeline) | Universal | Universal |
| Operating cost (heating) | Lowest — ~$0.04/kWh equivalent | Higher than gas — ~$0.06/kWh eq. | Highest — ~$0.14/kWh | Lowest to mid — COP 2.5–3.5 |
| Installation cost (London ON) | From $3,400 | From $3,900 | From $2,500 | From $3,700 |
| Enbridge $650 rebate | Yes — 95%+ AFUE | No | No | No (separate grant programs) |
| Greener Homes / OHRSP grants | No | Yes (up to $12,500 combined) | No | Yes (up to $12,500 combined) |
| TSSA LP certification required | No | Yes — Hawana holds LP cert | No | No |
| Best for | Most London Ontario homes | Rural SW Ontario without gas | Older condos, very small spaces | Propane homes, all-electric buildings |
When a heat pump is a better choice than a gas furnace: For rural Southwestern Ontario homes on propane — Aylmer, Grand Bend, Strathroy area — a cold-climate heat pump paired with Greener Homes grants (up to $5,000) and OHRSP grants (up to $7,500) can be more cost-effective than a propane furnace over a 10-year horizon. Hawana advises on the heat pump vs propane comparison at every estimate visit for rural propane homes. For homes on the Enbridge natural gas grid, gas furnace is almost always the most cost-effective heating choice.
Your Gas Furnace Specialist — London Ontario & Southwestern Ontario
Abdullah Ghzail — Lead HVAC Technician & Founder
Abdullah has diagnosed, repaired, and installed gas furnaces across London Ontario and Southwestern Ontario since 2018 — single-stage vs two-stage vs modulating explained honestly at every estimate because a homeowner who understands what they are buying makes better decisions; heat exchanger cracks condemned in writing because a verbal recommendation to replace is not good enough when the reason is a CO safety issue; propane furnace installations across rural Southwestern Ontario with LP propane TSSA certification because rural communities deserve the same level of service as London. Gas from $3,400. $175 diagnostic. Enbridge $650 rebate handled. No rental. BBB A+. 138 five-star reviews.
Furnace Reviews — London Ontario
138 five-star reviews — cracked heat exchanger on 21-year Carrier condemned in writing, honest two-stage vs modulating advice (Goodman recommended over Lennox), flame sensor + return air duct diagnosis on high-limit trip. Read all ↗
"Called Hawana when our 21-year-old Carrier made a grinding noise then stopped heating. The technician explained what the inducer motor does in a way that made the diagnosis understandable. He confirmed the inducer was failing but also found a heat exchanger crack — confirmed by elevated CO in the circulating air. He condemned the furnace in writing and quoted a Goodman 96% AFUE from $3,400. Same week installation, Enbridge $650 rebate handled. The written condemnation and the explanation of what a cracked heat exchanger means gave us complete confidence."
"I had researched furnace types for months — single-stage, two-stage, modulating — and couldn't get a straight answer until I called Hawana. The technician explained the difference practically for our specific home: 1,600 sq ft in Westmount, newer build, fairly tight. His recommendation was a two-stage Goodman at $3,400 rather than the more expensive modulating Lennox I was considering. His reasoning: the comfort difference between two-stage and modulating in our size home is marginal, and the Lennox payback is too long. That kind of honest advice is exactly what I needed."
"Furnace kept firing then shutting off after 30 seconds. Before calling Hawana I replaced the filter — it resolved the problem for a week then started again. Hawana diagnosed both a partially blocked return air duct and a dirty flame sensor. Cleaned the sensor, cleared the duct, recommended monthly filter checks given our two dogs. Furnace running perfectly since. $175 diagnostic, total under $400. Everything explained clearly before any work started."
Gas Furnace Service — Southwestern Ontario
Same published pricing across the entire service area. No travel surcharge. 24/7 emergency throughout.
Furnace FAQ — London Ontario 2026
How furnaces work, types, lifespan, components, fuel types, signs to replace, sizing, and what services Hawana provides across London Ontario and Southwestern Ontario.
Furnace Repair or Installation in London Ontario?
Gas furnace from $3,400 — all-in, Enbridge $650 rebate handled. $175 repair diagnostic applied to cost. 24/7 zero surcharge. TSSA certified. BBB A+. 138 five-star reviews. Published pricing before you call.
More Furnace & Heating Services
🔥 Furnace Hub — All Services
Repair $175, install from $3,400, maintenance $149/yr. Emergency 24/7.
🔥 Furnace Installation — From $3,400
Goodman, Carrier, Lennox. Enbridge $650. Combo with AC or tankless from $6,500.
🔧 Repair & Maintenance — $175 / $149/yr
Emergency repair and annual tune-up. Priority dispatch Premium plan.
🌡️ Heat Pumps — OHRSP $7,500
Cold-climate heat pump replaces furnace + AC. Better for propane homes.
❄️ Air Conditioning — From $3,500
Combo furnace + AC from $6,500. One visit, one permit.
💇 Gas Line Services
TSSA certified. Gas valve, line upgrades, pressure testing.
