Water Heaters and Hot Water Systems Flashcards
7 cards from real Journeyman Plumbers Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Water Heaters and Hot Water Systems flashcards as text
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?
Answer: 150 PSI
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.
Which pipe material is NOT permitted for use as a T&P relief valve discharge pipe?
Answer: Schedule 40 PVC pipe
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.
What is the primary energy advantage of a tankless (on-demand) water heater compared to a conventional storage water heater?
Answer: Elimination of standby heat loss
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.
What is the purpose of a thermostatic mixing valve (tempering valve) installed at the outlet of a water heater?
Answer: To blend hot and cold water to deliver a safe, preset mixed temperature
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.
What is the minimum horizontal clearance required between a power vent water heater exhaust termination cap and a window or door opening?
Answer: 4 feet
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.
When may a plumber reduce the diameter of a T&P relief valve discharge pipe below the size of the valve outlet?
Answer: Never — reducing the pipe size below the valve outlet is prohibited
T&P relief valve discharge pipes must never be reduced below the size of the valve outlet, as a smaller pipe could restrict flow and prevent the valve from relieving pressure effectively.
What is required when a water heater is installed in an area subject to flooding or where the unit could be submerged?
Answer: The heater must be elevated above the base flood elevation
Water heaters must be elevated above the base flood elevation (BFE) in flood-prone areas to prevent submersion, which could damage the unit and create hazards from gas leaks or electrical faults.