The answer to 'why is my drain trap no hot water' is that the drain trap is not receiving hot water from the plumbing system. This is likely due to a problem with the hot water supply, such as a malfunctioning water heater or a blockage in the hot water line. The drain trap is designed to hold water to prevent sewer gases from entering the home, and it relies on the hot water supply to maintain the proper water level and temperature.
Some common causes of this issue include a broken or malfunctioning water heater, a clogged hot water line, or a problem with the plumbing fixtures that are connected to the hot water supply. If the water heater is not producing enough hot water, or if the hot water line is blocked, the drain trap will not receive the necessary hot water to maintain its proper function.