Sudden temperature drops in Texas can cause severe damage to exterior-mounted tankless water heaters. Isolation valves, which connect the water supply to the unit, are especially prone to freezing and cracking. This can lead to water leaks, system failure, and costly repairs. Power outages during winter storms render built-in freeze protection ineffective, leaving systems vulnerable. Homeowners who fail to winterize their units risk losing access to hot water and facing significant repair costs (Burnside AC, 2026).