Massachusetts Plumbers Journeyman Practice Exam

What is the minimum discharge requirement in BTU per hour for the temperature relief valve to be compliant?

1. Equal to the tank size

2. Twice the tank size

3. Half the tank size

4. Equal to the heat source input

The correct answer is: Equal to the heat source input

The minimum discharge requirement for a temperature relief valve is indeed compliant when it is equal to the heat source input. This is critical because the relief valve is designed to protect the water heater from excessive pressure and temperature buildup. The heat input of the system determines how much energy is being applied, and consequently, how quickly the water heater can potentially build up dangerous levels of pressure if something were to go wrong. By ensuring that the discharge capacity of the temperature relief valve matches the heat source input, the system can effectively manage the excess pressure and prevent hazardous situations. This is particularly important in maintaining safety standards in plumbing systems, as the valve serves as a critical fail-safe. The other options focus on tank size, which does not adequately account for the rate at which heat is being added to the water. Ultimately, proper regulation requires that the valve's discharge capabilities are aligned with the heat input rather than the tank's volume.