In short
- A boom as the burners light is what HVAC guides link to delayed ignition, and they treat it as urgent.
- Squealing and grinding point to blower motor bearings or a worn belt; a blower motor runs $300–$650 on HomeStars' Canada-wide guide.
- Enbridge Gas lists hissing or whistling near the meter, pipes or appliances among the warning signs of a gas leak.
Typical prices in Ottawa
| Job | Typical range | Notes |
|---|---|---|
| Diagnostic or service call | $80–$150 | Canada-wide guide; often credited to the repair, so ask |
| Ignitor replacement | $150–$300 | Canada-wide guide |
| Blower motor replacement | $300–$650 | Canada-wide guide |
| Draft inducer motor or gas valve failure | $700–$1,500+ | Canada-wide guide, total for a major component |
| Heat exchanger repair or replacement | $500–$1,500+ | Canada-wide guide |
| Burner cleaning | $80–$150 | Canada-wide maintenance guide |
| HVAC labour, hourly | $75–$150/h | HomeStars Ottawa guide, average about $110 an hour |
| After-hours surcharge | $100–$200+ | Added to the base bill, Canada-wide guide |
Sources. Costs: HomeStars, Furnace Repair Cost, Canada-wide, seen 29.10.2026; HomeStars, Furnace Maintenance Cost, Canada-wide, seen 29.10.2026; HomeStars, Heating and Cooling Costs in Ottawa, seen 29.10.2026. Sounds and causes: HVAC.com, Why Is My Furnace So Loud?, US guide, seen 29.10.2026; HomeTips, Furnace Making Noise, US guide, seen 29.10.2026; Trane, Gas Furnace Troubleshooting and Trane, Oil Furnace Troubleshooting, seen 29.10.2026. Gas and CO safety: Enbridge Gas, Smell gas? and Ontario, Carbon monoxide safety, seen 29.10.2026. Gas work: TSSA, Be Fuels Wise and TSSA, Find a Registered Fuels Contractor, seen 29.10.2026. Ottawa distributor: OEB Decision EB-2024-0339, seen 29.10.2026. Contracts: Ontario, guide for home renovation businesses, seen 29.10.2026. Canada-wide figures are labelled; the company that calls you prices your own repair.
Name the sound, then the moment
Trane’s oil furnace page advises owners to note the sound and when it occurs, then pass both to the dealer. The table sums up what public HVAC guides link each sound to.
| Sound | When people hear it | What guides link it to |
|---|---|---|
| Bang or boom | As the burners light | Delayed ignition: dirty burners, low gas pressure, a failing ignition system |
| Bang in the ducts | Once warm air arrives | Ductwork expanding (HomeTips) |
| Squeal, screech or grinding | While the fan runs | Blower motor bearings, a worn belt |
| Rattle | During a cycle | A loose panel or screw, loose ductwork |
| Loud hum or buzz | Fan start or all the time | Blower motor, capacitor, transformer, loose wiring |
| Continuous clicking | Around start-up | Ignition system or a relay |
| Whistle | While air moves | Clogged filter, duct leak; near gas piping, a possible gas leak |
Bangs and booms when the burners light
A boom from the cabinet as the furnace starts is what HVAC.com calls delayed ignition, where gas collects and lights all at once. It calls the problem potentially dangerous. HomeTips adds a second source of banging: ducts expanding as warm air reaches them.
Timing separates the two: a boom at ignition belongs with the burners, a pop from a duct run with the metal.
Squeals, grinding and hums from the fan side
HVAC.com and HomeTips connect squealing to blower motor bearings or a worn belt, and HomeTips adds grinding. A soft, steady hum is normal on HVAC.com; a louder hum or buzz may be electrical. For a noisy oil furnace, Trane names a loose access panel or an unlubricated belt.
Rattles, pops and whistles in the ducts
HVAC.com puts rattling down to a loose panel, screw or duct, and whistling to air forcing its way through a clogged filter or a duct leak. A whistle traced to one register or duct joint saves the technician time.
One whistle belongs elsewhere. Enbridge Gas lists hissing or whistling near the meter, pipes or appliances among the warning signs of a gas leak.
When the sound is a safety matter
- Hissing near gas piping, or a rotten-egg smell. Enbridge Gas, the gas supplier in the City of Ottawa, says to leave the area and call 1-866-763-5427 or 911 from a safe location.
- A CO alarm sounding. Ontario says to get everyone out and call 9-1-1 from outside. Our carbon monoxide page covers where alarms are required.
- Strange noises from a gas furnace. Trane tells gas furnace owners to call an HVAC professional right away for strange noises. HomeStars’ repair guide says a furnace should not run with a cracked heat exchanger.
- Snow at the vents. Ontario’s CO page asks owners to keep outside furnace vents clear of snow and debris. After an Ottawa snowfall, say whether the pipes on the outside wall are buried.
If a furnace is found unsafe and red-tagged, see red tag notices.
What the repair bill is built from
A noise repair is usually one part plus labour. HomeStars’ Canada-wide repair guide lists a diagnostic visit at $80–$150, often credited to the repair, an ignitor at $150–$300 and a blower motor at $300–$650. A draft inducer motor or gas valve failure can bring the total to $700–$1,500 or more.
In Ottawa, HVAC labour runs $75–$150 an hour, per HomeStars’ Ottawa guide. The Canada-wide guide adds $100–$200 or more for after-hours calls. The repair guide suggests a second opinion before approving a blower motor, control board or gas valve on the spot. More figures by part: furnace repair cost in Ottawa.
The quote should name the part making the noise and list parts, labour, any after-hours charge and HST separately. Ontario’s guide for home renovation businesses says a contract over $50 needs a written agreement and the final price may not exceed the estimate by more than 10%.
Who handles your request
Ottawa Heating Desk passes your request to one independent local heating company. That company calls you back, sends a technician to find the source of the sound and quotes the repair. You decide whether the work goes ahead.
Questions to ask the company
- Which part is making the noise, and how did you confirm it?
- Is the furnace safe to run until the part arrives?
- Is the diagnostic fee credited if I go ahead with the repair?
- What do the part and the labour cost, on separate lines, with HST?
- Is your company registered with TSSA, so I can check it on TSSA's lookup?
Have this ready for the call
- A short phone recording of the sound, started a few seconds before it begins
- When it happens: as the burners light, while the fan runs, or as the furnace shuts off
- Where it seems to come from: the furnace cabinet, a duct run, one register or the vent pipe
- Brand, model and age from the label, and the fuel: natural gas, propane, oil or electric
- The filter type and the date it was last changed
- A photo of the vent pipes on the outside wall if snow has drifted around them
Questions people ask
Is a loud bang when the furnace starts dangerous?
HVAC guides link a bang at start-up to delayed ignition, where gas collects and lights all at once, and HVAC.com calls it potentially dangerous. Trane tells owners of gas furnaces to call an HVAC professional right away for strange noises. Mark the request as urgent and say the boom comes at ignition.
The furnace squeals when the fan starts. What is likely?
Guides name worn blower motor bearings or a worn belt on a belt-driven fan. HomeStars’ Canada-wide guide puts a blower motor replacement at $300–$650; a belt or bearing job is priced after the technician sees it.
Is humming normal?
HVAC.com treats a soft, steady hum as normal. A louder hum or a buzz may point to an electrical problem: a failing blower motor, capacitor, transformer or loose connection.
Can a furnace noise mean carbon monoxide?
A noise alone tells you little about CO. HomeStars’ repair guide says a furnace should not run with a cracked heat exchanger because of the CO risk. Ontario requires a CO alarm next to each sleeping area of a home with a fuel-burning appliance, and since 1 January 2026 on every storey.
Who may repair a gas furnace in Ontario?
TSSA says furnaces and fuel-fired appliances must be maintained by TSSA-registered contractors, who must employ certified gas technicians. Its website has a lookup to check registration.
