What size wire mesh screen should cover combustion air vent openings that terminate on the outside of a building?

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The appropriate size for wire mesh screens covering combustion air vent openings that terminate on the outside of a building is 1/4 inch. This size is adequate for preventing the entry of small animals and debris while allowing sufficient airflow necessary for combustion processes within appliances.

Using a mesh screen that is too small, such as 1/8 inch, could restrict airflow, leading to potential combustion efficiency issues or safety hazards, such as the risk of carbon monoxide buildup. Conversely, larger sizes, like 1/2 inch or 3/4 inch, may not effectively prevent small pests from entering through the vent, potentially creating blockages or introducing contaminants.

In summary, a 1/4 inch wire mesh screen strikes a balance between protection against pests and allowing enough air for proper combustion, which is critical for the safe operation of heating appliances.

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