How does outside temperature influence chimney draft?

The influence of outside temperature on chimney draft is significant because the draft is affected by the temperature difference between the hot gases inside the chimney and the cooler outside air. When outside temperatures are lower, this creates a greater temperature differential. The hotter the gases inside the chimney compared to the outside air, the more buoyant the gases become, leading to an increase in draft. This enhanced upward movement helps to efficiently remove combustion gases from the appliance.

Conversely, when outside temperatures are higher, the temperature differential diminishes, which can reduce the effectiveness of the draft. This is due to the fact that the warmer outside air can cause the gases within the chimney to cool more quickly, thereby reducing their buoyancy and resulting in a weaker draft.

Therefore, lower outside temperatures can indeed improve chimney draft, facilitating better venting of combustion gases and contributing to the overall efficiency of the heating system.