The answer to 'why is my shut-off valve no hot water' is that the shut-off valve may be closed or malfunctioning, preventing hot water from reaching the faucet. This could be due to a problem with the water heater, plumbing lines, or the shut-off valve itself.
Common causes include a stuck or corroded shut-off valve, a problem with the water heater (such as a malfunctioning thermostat or heating element), or a blockage in the plumbing lines. Symptoms may include no hot water coming from the faucet or the water taking a long time to heat up. Solutions can range from simply turning the shut-off valve back on to replacing the valve or repairing the water heater, depending on the specific issue.