NSS Installation and Setup Procedures 3 — Questions and Answers
Question 1: What is the correct pipe size for the cold water inlet on a Navien NPE-240A2 tankless water heater?
- 1/2 inch NPT
- 3/4 inch NPT (Correct answer)
- 1 inch NPT
- 1-1/4 inch NPT
Correct answer: 3/4 inch NPT
The NPE-240A2 requires 3/4-inch NPT connections for both the cold water inlet and hot water outlet.
Question 2: When installing Navien's NFC series combi-boiler, what is the purpose of the buffer tank connection?
- To store excess natural gas
- To provide hydraulic separation and prevent short-cycling of the boiler (Correct answer)
- To act as a secondary heat exchanger
- To store condensate before neutralization
Correct answer: To provide hydraulic separation and prevent short-cycling of the boiler
A buffer tank provides hydraulic separation and sufficient water volume to prevent short-cycling of the combi-boiler.
Question 3: Which DIP switch setting on a Navien NPE series unit enables the 'comfort flow' recirculation mode?
- DIP switch 1, position ON
- DIP switch 3, position ON (Correct answer)
- DIP switch 5, position ON
- DIP switch 7, position ON
Correct answer: DIP switch 3, position ON
DIP switch 3 in the ON position activates the built-in comfort flow (recirculation) feature on NPE series units.
Question 4: During outdoor installation of a Navien tankless unit, what is the minimum ambient temperature rating for the unit's operation?
- -4°F (-20°C) (Correct answer)
- 14°F (-10°C)
- 32°F (0°C)
- 40°F (4°C)
Correct answer: -4°F (-20°C)
Navien outdoor units are rated for ambient temperatures as low as -4°F (-20°C) with the built-in freeze protection active.
Question 5: What action must be taken if the incoming gas pressure to a Navien unit is below the minimum required 3.5 inches W.C.?
- Adjust the internal regulator to compensate
- Contact the gas utility to resolve the supply pressure issue before startup (Correct answer)
- Install the unit and run it at reduced capacity
- Replace the gas valve with a higher-sensitivity model
Correct answer: Contact the gas utility to resolve the supply pressure issue before startup
If supply pressure is below 3.5 inches W.C., the gas utility must correct the pressure before the unit is commissioned.
Question 6: When mounting a Navien unit on an exterior wall, how should the vent termination be positioned relative to gas meters and electrical panels?
- At least 1 foot away from gas meters and 3 feet from electrical panels
- At least 3 feet away from gas meters and electrical panels
- At least 4 feet away from gas meters and 6 feet from electrical panels (Correct answer)
- At least 6 feet away from both gas meters and electrical panels
Correct answer: At least 4 feet away from gas meters and 6 feet from electrical panels
Navien installation guidelines require vent terminations to be at least 4 feet from gas meters and 6 feet from electrical panels.
Question 7: What is the required electrical supply for most Navien tankless water heaters installed in the United States?
- 120V / 15A dedicated circuit (Correct answer)
- 120V / 20A dedicated circuit
- 240V / 30A dedicated circuit
- 240V / 50A dedicated circuit
Correct answer: 120V / 15A dedicated circuit
Standard Navien tankless water heaters require a 120V / 15A dedicated circuit for the electronic controls and ignition.
NSS Installation and Setup Procedures 3
What is the correct pipe size for the cold water inlet on a Navien NPE-240A2 tankless water heater?