Journeyman Plumbers Exam Water Heaters and Hot Water Systems 3

Question 1

A water heater is rated for a maximum working pressure of 150 PSI. What is the maximum pressure rating allowed for the T&P relief valve installed on this heater?

Accepted Answer

150 PSI

Answer

The T&P relief valve must be rated at or below the maximum allowable working pressure of the water heater so it opens before the vessel reaches its pressure limit.

Question 2

Which pipe material is NOT permitted for use as a T&P relief valve discharge pipe?

Accepted Answer

Schedule 40 PVC pipe

Answer

Schedule 40 PVC is not approved for T&P relief valve discharge because it can soften and fail when exposed to the superheated water (up to 210°F) that may discharge from the valve.

Question 3

What is the primary energy advantage of a tankless (on-demand) water heater compared to a conventional storage water heater?

Accepted Answer

Elimination of standby heat loss

Answer

Tankless water heaters eliminate standby heat loss by only heating water when demand exists, unlike storage heaters that continuously maintain a tank of hot water.

Question 4

What is the purpose of a thermostatic mixing valve (tempering valve) installed at the outlet of a water heater?

Accepted Answer

To blend hot and cold water to deliver a safe, preset mixed temperature

Answer

A thermostatic mixing valve blends hot water from the tank with cold water to deliver a safe preset temperature (typically 120°F) to fixtures, allowing the tank to store water at 140°F for Legionella control.

Question 5

What is the minimum horizontal clearance required between a power vent water heater exhaust termination cap and a window or door opening?

Accepted Answer

4 feet

Answer

Power vent exhaust terminations must be located at least 4 feet horizontally from windows, doors, and other openings to prevent combustion gases from re-entering the building.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Water Heaters and Hot Water Systems 3