What is the minimum clearance on all sides and the rear of an unlisted water heater?

The minimum clearance requirement for an unlisted water heater is established to ensure proper ventilation, allow for servicing, and minimize the risk of fire hazards. Specifically, the NFPA 58 code emphasizes that adequate space is necessary around appliances, particularly those that are unlisted or not subject to the same testing and certification standards as listed appliances.

In this case, the 12 inches clearance is the standard measurement specified for unlisted water heaters, which helps in promoting safety and operational efficiency. This clearance allows sufficient air circulation to the appliance, reducing the risk of overheating and ensuring that any heat or combustion products can dissipate effectively without risk of ignition.

Understanding this clearance is critical for installation practices, as inadequate space can lead to dangerous conditions, such as restricted airflow or increased fire risk, necessitating strict adherence to the regulated distances outlined in the code.