The answer to 'supply line no hot water' is that the most common causes are a faulty water heater, a problem with the home's plumbing system, or a clogged or broken supply line. Symptoms may include lukewarm or cold water coming from the faucet and a lack of hot water throughout the home. Solutions can range from simple fixes like unclogging the supply line to more complex issues like replacing the water heater or repairing the plumbing system.
If the problem is isolated to a single faucet or appliance, it may be a DIY fix. However, if the issue is with the overall plumbing system or water heater, it's best to call a professional plumber. They have the expertise and tools to properly diagnose and repair the problem, ensuring the safety and functionality of your home's plumbing.