How far must the flue gas outlet be above grade?

The correct answer indicates that the flue gas outlet must be 1 foot above grade. This requirement typically stems from safety regulations aimed at ensuring that flue gases, which can contain harmful substances and high temperatures, are adequately dispersed into the atmosphere and do not pose risks to people or structures nearby.

Positioning the flue gas outlet just 1 foot above grade helps to ensure that the exhaust gases are released at a sufficient height to minimize the chance of re-entering living spaces or affecting ground-level air quality. Such regulations are in place to prevent issues such as carbon monoxide build-up, which can occur if exhaust gases are not vented properly.

While it may seem beneficial to have the outlet higher, codes are designed to balance safety with practical considerations for installation and maintenance. Higher installations may also introduce additional challenges in terms of structural integrity and access for service and repairs. Thus, a requirement of 1 foot provides an effective compromise for safety standards while still being practical for operational needs.