NATE GAS HEATING EXAM COMPREHENSIVE
REVIEW 2026
◉ The gas control valve may be damaged if exposed to an inlet
pressure above what? Answer: 14 inch W.C.
◉ How many elbows and joints should a vent connector have?
Answer: As few as possible to reduce resistance of flue gases.
◉ Under what conditions, if any may the technician route the
exhaust of the furnace into the exhaust vent of the water heater:
Answer: Under no conditions may you use the water heater exhaust
vent.
◉ How may a technician terminate the intake and exhaust for
proper operation of a high efficiency gas furnace when using
scheduled 40 PVC pipe: Answer: By using the specific manufacturers
termination kit or make one to meet their requirements.
◉ When suspended with metal strap and no saddle, flexible duct
should be: Answer: supported with a minimum strap width of
1/2".
,◉ A technician is installing a gas furnace and the customer has
decided not to install an air conditioner. Making this decision, the
affect it will have on the installation of the supply ductwork is:
Answer: Leave adequate space should be allowed for addition of a
coil in the future when feasible.
◉ Leveling of a Mercury bulb is __________ Answer: Critical
◉ Spray-type atomizing humidifiers are installed to do what?
Answer: Discharge moisture into the supply duct.
◉ Electronic air cleaners (EAC) installed in a gas furnace system
should be wired so they: Answer: Only operate any time the EAC On-
Off switch is turned to ON.
◉ The LP gas manifold pressure is commonly what? Answer: 10 to
11 in. W.C.
◉ The polarity of a 120V gas furnace equipped with electronic flame
rectification is important because: Answer: The ignition control may
not prove flame.
◉ Using a voltmeter, a technician can determine voltage drop at a
gas furnace: Answer: With the furnace not operating and then with
the furnace operating.
, ◉ The setting on a 4 speed PSC blower motor can be changed by
changing the: Answer: Motor tap connection.
◉ When starting up a dual system, the temperature rise method for
determining airflow cannot be used with compressor cycle of the
heat pump because: Answer: The capacity of the system varies too
much with outdoor temperature.
◉ The flame pattern a technician would expect to see on a properly
operating single stage gas furnace equipped with "in shot" type
burner is a: Answer: Hard and forceful flame with a light blue
appearance and little or no yellow.
◉ What is recommended method for a pressurization leak test of a
fuel gas pipe? Answer: Compressed air
◉ What is a diaphragm type differential pressure gauge used for?
Answer: Measure air pressure.
◉ The pressure reading on a manometer is expressed in: Answer:
Inches of water.
◉ A technician measures the return air temperature of a 100,000
BTU output gas furnace to be 65°F and the supply side air
REVIEW 2026
◉ The gas control valve may be damaged if exposed to an inlet
pressure above what? Answer: 14 inch W.C.
◉ How many elbows and joints should a vent connector have?
Answer: As few as possible to reduce resistance of flue gases.
◉ Under what conditions, if any may the technician route the
exhaust of the furnace into the exhaust vent of the water heater:
Answer: Under no conditions may you use the water heater exhaust
vent.
◉ How may a technician terminate the intake and exhaust for
proper operation of a high efficiency gas furnace when using
scheduled 40 PVC pipe: Answer: By using the specific manufacturers
termination kit or make one to meet their requirements.
◉ When suspended with metal strap and no saddle, flexible duct
should be: Answer: supported with a minimum strap width of
1/2".
,◉ A technician is installing a gas furnace and the customer has
decided not to install an air conditioner. Making this decision, the
affect it will have on the installation of the supply ductwork is:
Answer: Leave adequate space should be allowed for addition of a
coil in the future when feasible.
◉ Leveling of a Mercury bulb is __________ Answer: Critical
◉ Spray-type atomizing humidifiers are installed to do what?
Answer: Discharge moisture into the supply duct.
◉ Electronic air cleaners (EAC) installed in a gas furnace system
should be wired so they: Answer: Only operate any time the EAC On-
Off switch is turned to ON.
◉ The LP gas manifold pressure is commonly what? Answer: 10 to
11 in. W.C.
◉ The polarity of a 120V gas furnace equipped with electronic flame
rectification is important because: Answer: The ignition control may
not prove flame.
◉ Using a voltmeter, a technician can determine voltage drop at a
gas furnace: Answer: With the furnace not operating and then with
the furnace operating.
, ◉ The setting on a 4 speed PSC blower motor can be changed by
changing the: Answer: Motor tap connection.
◉ When starting up a dual system, the temperature rise method for
determining airflow cannot be used with compressor cycle of the
heat pump because: Answer: The capacity of the system varies too
much with outdoor temperature.
◉ The flame pattern a technician would expect to see on a properly
operating single stage gas furnace equipped with "in shot" type
burner is a: Answer: Hard and forceful flame with a light blue
appearance and little or no yellow.
◉ What is recommended method for a pressurization leak test of a
fuel gas pipe? Answer: Compressed air
◉ What is a diaphragm type differential pressure gauge used for?
Answer: Measure air pressure.
◉ The pressure reading on a manometer is expressed in: Answer:
Inches of water.
◉ A technician measures the return air temperature of a 100,000
BTU output gas furnace to be 65°F and the supply side air
