Journeyman Plumbers Exam Water Heaters and Hot Water Systems 2

Question 1

At what minimum storage temperature is Legionella bacteria effectively inhibited in a hot water system?

Accepted Answer

140°F (60°C)

Answer

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.

Question 2

What does the 'first-hour rating' (FHR) indicate about a storage water heater?

Accepted Answer

The total gallons of hot water the unit can deliver in the first hour starting with a full tank

Answer

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.

Question 3

Which type of water heater venting uses a concentric pipe system to draw combustion air from outside while exhausting combustion gases directly outdoors?

Accepted Answer

Direct vent (sealed combustion)

Answer

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.

Question 4

What is the maximum hot water delivery temperature typically permitted at fixtures in healthcare facilities and nursing homes?

Accepted Answer

110°F

Answer

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.

Question 5

An atmospheric gas water heater is installed in a confined mechanical room. What is required to ensure safe operation?

Accepted Answer

A dedicated combustion air supply to the confined space

Answer

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.

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Practice Test

Journeyman Plumbers Exam Water Heaters and Hot Water Systems 2