If an auxiliary drain pan under an air handler cannot gravity drain, what alternative protection is acceptable by Code?

The acceptable alternative protection for an auxiliary drain pan under an air handler that cannot gravity drain is a water level detection device. This device is designed to monitor the water level within the drain pan. If the water level rises to a certain threshold—indicating a potential blockage or backup—it will trigger a safety mechanism, such as sending an alarm or shutting off the air handler. This proactive approach helps to prevent water damage, mold growth, and other issues associated with excess water accumulation.

Water level detection devices are commonly required by plumbing codes in situations where gravity drainage is not feasible. They provide a reliable method of ensuring that the system does not lead to overflows, making them a crucial safety feature in HVAC installations. This adherence to code requirements promotes safety and efficiency in residential and light commercial HVAC applications.