The answer to 'why is my pressure regulator no hot water' is that a malfunctioning pressure regulator is a common cause of no hot water. The pressure regulator controls the water pressure entering your home, and if it's not functioning properly, it can disrupt the flow of hot water.
Some common symptoms of a bad pressure regulator include low water pressure, fluctuating water pressure, or no hot water at all. This can happen if the regulator is set too low, worn out, or stuck open or closed. To fix the issue, you may need to adjust, repair, or replace the pressure regulator. However, this is a job best left to a professional plumber, as improper handling can lead to further damage or even water leaks.