PC Troubleshooting & Diagnostics 2

Question 1

A customer reports that their water heater produces hot water for only a few minutes before it turns cold. What is the MOST likely cause?

Accepted Answer

Faulty dip tube allowing cold and hot water to mix

Answer

A broken or missing dip tube allows incoming cold water to mix directly with hot water near the top of the tank, drastically reducing hot water supply time.

Question 2

A floor drain is emitting sewer gas odors intermittently. The FIRST diagnostic step should be to:

Accepted Answer

Pour water into the drain to refill the trap

Answer

An evaporated P-trap is the most common cause of intermittent sewer gas odors from floor drains, and pouring water restores the water seal immediately.

Question 3

A pressure gauge on a well pump system reads normal when the pump is off but drops significantly when any fixture is opened. This indicates:

Accepted Answer

Waterlogged pressure tank

Answer

A waterlogged pressure tank has lost its air cushion, causing rapid pressure drop when water is drawn because the tank holds almost no reserve.

Question 4

A gas water heater pilot light keeps going out repeatedly. After relighting, it extinguishes within seconds. The MOST likely faulty component is the:

Accepted Answer

Thermocouple

Answer

A defective thermocouple fails to sense the pilot flame and signals the gas valve to close, extinguishing the pilot within seconds of lighting.

Question 5

During a visual inspection, a plumber notices the cold water pipe at a water heater is warm to the touch when no hot water is being used. This condition is called:

Accepted Answer

Thermal siphoning / convection loop

Answer

Thermal siphoning occurs when hot water naturally rises and circulates backward through cold supply lines due to convection when no check valve is present.

(PC) Plumber Certification Practice Test

(PC) Plumber Certification Practice Test

PC Troubleshooting & Diagnostics 2