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
At what minimum storage temperature is Legionella bacteria effectively inhibited in a hot water system?
Answer: 140°F (60°C)
Legionella bacteria are killed at 140°F (60°C); storing domestic hot water at or above this temperature prevents bacterial colonization and growth in the system.
What does the 'first-hour rating' (FHR) indicate about a storage water heater?
Answer: The total gallons of hot water the unit can deliver in the first hour starting with a full tank
First-hour rating (FHR) measures how many gallons of hot water a storage water heater can supply per hour when starting with a fully heated tank, indicating its ability to meet peak demand.
Which type of water heater venting uses a concentric pipe system to draw combustion air from outside while exhausting combustion gases directly outdoors?
Answer: Direct vent (sealed combustion)
Direct vent (sealed combustion) water heaters use a concentric or two-pipe system that draws all combustion air from outdoors and exhausts gases outside, making them completely independent of indoor air.
What is the maximum hot water delivery temperature typically permitted at fixtures in healthcare facilities and nursing homes?
Answer: 110°F
Healthcare facilities typically limit hot water to 110°F at fixture outlets to protect vulnerable patients — including the elderly, infants, and those with reduced sensitivity — from scalding.
An atmospheric gas water heater is installed in a confined mechanical room. What is required to ensure safe operation?
Answer: A dedicated combustion air supply to the confined space
Atmospheric gas water heaters require adequate combustion air; when installed in a confined space, openings or ducts providing a dedicated combustion air supply from outside or an adjacent unconfined space are required.
What is the minimum required diameter of a drain line from a water heater drain pan per most US plumbing codes?
Answer: 3/4 inch
Water heater pan drain lines must be at least 3/4 inch in diameter to carry away water from a leaking or failed water heater quickly and prevent flooding.
In which seismic design categories are water heaters typically required to be anchored or strapped to prevent overturning during an earthquake?
Answer: Seismic Design Categories C, D, E, and F (high seismic risk areas)
Seismic strapping is required in higher seismic design categories (C through F) to prevent water heaters from tipping during earthquakes, which could rupture gas lines and cause fires or flooding.