My gas fireplace makes a high-pitched whistling sound when the wind blows hard in Ottawa — how much does fixing that cost?

That whistling sound during high winds is almost certainly a pressure or airflow issue with your venting system, and it is one of the more common complaints from Ottawa gas fireplace owners — particularly during the gusty conditions along the Ottawa River corridor and in exposed suburban areas like Barrhaven, Kanata, and Orleans. The good news is that this is usually a diagnosable and fixable problem, and it rarely requires replacing the fireplace itself.

The most common culprit is the exterior vent termination cap. Direct-vent gas fireplaces exhaust through a coaxial vent pipe that terminates on an exterior wall or through the roof, and the cap at that termination point is designed to prevent backdrafting while allowing exhaust gases to escape. When wind hits that cap at certain angles — especially during Ottawa's winter northwest winds — it can create a pressure differential that causes the vent pipe to resonate, producing exactly the kind of high-pitched whistle you are describing. Replacing the termination cap with a wind-resistant model designed for high-exposure locations typically costs $150 to $400 including labour, and it solves the problem in many cases.

If the cap is not the issue, the next suspects are the vent pipe joints themselves. In Ottawa's extreme temperature range — from -30°C in January to +35°C in summer — metal vent components expand and contract significantly over the years. Joints that were sealed properly at installation can develop small gaps that whistle under wind pressure. A TSSA-licensed gas fitter can inspect the full vent run, reseal any compromised joints, and check that all connections are properly secured. This kind of service call typically runs $150 to $250 for the diagnostic visit, with any additional parts and labour on top.

A less common but worth-mentioning cause is the glass or door seal on the firebox itself. If the gasket that seals the glass panel to the firebox frame has deteriorated — which happens over time, especially in a fireplace that sees heavy use during Ottawa's long heating season — wind-driven pressure changes can cause air to whistle through the gap. Gasket replacement is a relatively straightforward repair costing $100 to $200 depending on the unit.

One important caution: do not ignore this issue or assume it is purely cosmetic. A gas fireplace that responds audibly to wind pressure changes is telling you that the venting system may not be fully sealed or properly balanced. An improperly vented gas appliance can allow combustion gases — including carbon monoxide — to enter the living space under certain wind conditions. Make sure your carbon monoxide detector is functioning and up to date, and have a TSSA-licensed gas fitter assess the system before the next Ottawa cold snap hits.

If you are ready to have someone look at it, you can browse gas fireplace service professionals through the Ottawa Construction Network directory at justynrookcontracting.com/directory — it is worth getting this sorted before the deep cold of January when service calls back up significantly.