For a 60,000 Btuh water heater with no draft diverter in a closet type enclosure, what is the appropriate lower opening size for air supply?

In considering the requirements for air supply to a water heater, particularly one with high BTU input in a closet-type enclosure, the appropriate ventilation is crucial for safe operation. For a 60,000 BTUh water heater, it is essential to ensure that there is adequate air supply to support combustion and prevent backdrafting or improper venting.

The requirement for ventilation openings is typically based on the BTU capacity of the appliance. In this case, a water heater rating of 60,000 BTUh generally necessitates a substantial opening to allow fresh air into the enclosure. Standard practices dictate that a specific square inch value of openings per BTU is required to maintain proper air flow.

Therefore, a 60 square inch lower opening provides the necessary airflow to adequately support the combustion process for a water heater of this size without the need for an upper opening. This arrangement ensures that there is a sufficient supply of air drawn in from below, which can contribute to efficient operation and safety, as the appliance will not struggle to intake the air needed for combustion.

In contrast, smaller openings would not meet the airflow requirements and could result in improper combustion, increased carbon monoxide levels, and operational inefficiencies, as the equipment would be starved of the necessary air