The answer to 'water heater freezing up' is that a water heater freezing up is typically caused by a malfunction that allows the water in the tank to freeze. Common symptoms include the water not getting hot, the tank feeling cold, and potentially leaking or bursting. Solutions can include insulating the tank, adjusting the thermostat, or repairing any issues with the heating element or other components.
In many cases, a frozen water heater can be addressed with some basic troubleshooting and DIY repairs. However, if the problem persists or you're not comfortable working on the unit, it's best to call in a professional HVAC technician to diagnose and repair the issue. They'll have the expertise and tools to get your water heater back up and running safely and efficiently.