The answer to 'water line no hot water' is that the most common causes are a faulty water heater, a problem with the plumbing system, or a malfunctioning mixing valve. Symptoms may include no hot water coming from any taps, lukewarm water, or hot water that runs out quickly. Solutions can range from simple DIY fixes like checking the water heater's thermostat or flushing the system, to more complex issues that require a professional plumber to repair or replace the water heater or other components.
If the issue is with the water heater, you may be able to troubleshoot and fix it yourself, such as adjusting the thermostat or flushing the tank. However, if the problem is in the plumbing system or requires more extensive repairs, it's best to call a licensed plumber to diagnose and resolve the issue properly and safely.