The Reliance standard condensing gas tankless water heater delivers robust, on-demand performance and the flexibility to install in practically any residential setting. Built-in X3 Scale Prevention Technology provides protection for the heat exchanger making it last three times longer compared to other brands tankless water heater and maintaining like-new performance,. Features a built-in control display for setting and reviewing up to two recirculating schedules, as well as checking heater status and error codes. Manage temperature settings and activate the heater and recirculation remotely with optional kits (sold separately). Also complies with Ultra-Low NOx regulations. Field convertible from natural gas to liquid propane, kit included, and can be installed indoors or outdoors with an outdoor vent cap kit (sold separately).