NATE Gas Heat Practice Guide QUESTIONS AND ANSWERS 100% ACCURATE.
Leveling of a Mercury bulb is __________ - Critical
Spray-type atomizing humidifiers are installed to do what? - Discharge moisture into the supply
duct.
Electronic air cleaners (EAC) installed in a gas furnace system should be wired so they: - Only
operate any time the EAC On-Off switch is turned to ON.
The LP gas manifold pressure is commonly what? - 10 to 11 in. W.C.
The polarity of a 120V gas furnace equipped with electronic flame rectification is important
because: - The ignition control may not prove flame.
Using a voltmeter, a technician can determine voltage drop at a gas furnace: - 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: - 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: - 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: - 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? - Compressed air
What is a diaphragm type differential pressure gauge used for? - Measure air pressure.
The pressure reading on a manometer is expressed in: - 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 temperature is 135°F. Calculate the CFM. - The CFM would be
1323.
A dirty or clogged air filter in an operating gas furnace can cause what? - Increase temperature
rise.
What can bent vanes on a direct drive blower wheel in a gas furnace cause? - Loss in airflow,
excessive blower motor wear, and increase noise.
, A gas clothes dryer can interfere with the operation of a nearby natural draft gas furnace with an
atmospheric burner by: - Stealing combustion air preventing complete fuel burning.
During a preventive maintenance check of a gas furnace, what should always be checked for on
the ductwork? - Ductwork should always be checked for leaks and damage.
When performing a cycle check during a preventive maintenance call, the technician should: -
~First check with the owner of the equipment for their opinion of performance.
~The next step is to turn the unit off at the thermostat system switch. ~Next the technician should
set the FAN switch to ON and check that the blower is running.
What measurements are required to calculate the CFM of a gas furnace are? - ~Entering air
temperature
~Leaving air temperature
~Outdoor ambient and rated capacity.
The reason for checking the temperature rise across the heat exchanger of a gas furnace is to: -
Compare temperature differential to nameplate rating.
The technician is checking the operation of an induced draft furnace with an atmospheric burner
and a direct ignition system. On a call for heat the sequence is what? - ~Vent blower comes on
~Igniter glows
~Main burner does not light
~The next check would be the gas supply and/or gas valve
The technician is servicing a gas furnace located in a basement and the complaint is "not enough
heat". The following conditions exist: - Properly sized furnace is operating correctly
Temperature rise is within specification
Filter is clean and CFM from blower is proper
The most likely problem with this system is the air side is leaking at one or more supply ducts.
The complaint is that there is static electricity throughout the house. The home has a bypass
humidifier. The technician has checked the humidistat and verified that it is set properly. - The
next check would be to see if the humidifier damper is open.
A customer complains the unit is "blowing cold air". The technician determines that the problem
occurs at the end of the heating sequence. The furnace used an electronic integrated blower
control. - The likely problem with the system is the blower off delay is set too long.
Undersized ductwork often causes: - ~High sound levels
~Insufficient air quantities
~High static pressures.
Leveling of a Mercury bulb is __________ - Critical
Spray-type atomizing humidifiers are installed to do what? - Discharge moisture into the supply
duct.
Electronic air cleaners (EAC) installed in a gas furnace system should be wired so they: - Only
operate any time the EAC On-Off switch is turned to ON.
The LP gas manifold pressure is commonly what? - 10 to 11 in. W.C.
The polarity of a 120V gas furnace equipped with electronic flame rectification is important
because: - The ignition control may not prove flame.
Using a voltmeter, a technician can determine voltage drop at a gas furnace: - 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: - 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: - 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: - 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? - Compressed air
What is a diaphragm type differential pressure gauge used for? - Measure air pressure.
The pressure reading on a manometer is expressed in: - 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 temperature is 135°F. Calculate the CFM. - The CFM would be
1323.
A dirty or clogged air filter in an operating gas furnace can cause what? - Increase temperature
rise.
What can bent vanes on a direct drive blower wheel in a gas furnace cause? - Loss in airflow,
excessive blower motor wear, and increase noise.
, A gas clothes dryer can interfere with the operation of a nearby natural draft gas furnace with an
atmospheric burner by: - Stealing combustion air preventing complete fuel burning.
During a preventive maintenance check of a gas furnace, what should always be checked for on
the ductwork? - Ductwork should always be checked for leaks and damage.
When performing a cycle check during a preventive maintenance call, the technician should: -
~First check with the owner of the equipment for their opinion of performance.
~The next step is to turn the unit off at the thermostat system switch. ~Next the technician should
set the FAN switch to ON and check that the blower is running.
What measurements are required to calculate the CFM of a gas furnace are? - ~Entering air
temperature
~Leaving air temperature
~Outdoor ambient and rated capacity.
The reason for checking the temperature rise across the heat exchanger of a gas furnace is to: -
Compare temperature differential to nameplate rating.
The technician is checking the operation of an induced draft furnace with an atmospheric burner
and a direct ignition system. On a call for heat the sequence is what? - ~Vent blower comes on
~Igniter glows
~Main burner does not light
~The next check would be the gas supply and/or gas valve
The technician is servicing a gas furnace located in a basement and the complaint is "not enough
heat". The following conditions exist: - Properly sized furnace is operating correctly
Temperature rise is within specification
Filter is clean and CFM from blower is proper
The most likely problem with this system is the air side is leaking at one or more supply ducts.
The complaint is that there is static electricity throughout the house. The home has a bypass
humidifier. The technician has checked the humidistat and verified that it is set properly. - The
next check would be to see if the humidifier damper is open.
A customer complains the unit is "blowing cold air". The technician determines that the problem
occurs at the end of the heating sequence. The furnace used an electronic integrated blower
control. - The likely problem with the system is the blower off delay is set too long.
Undersized ductwork often causes: - ~High sound levels
~Insufficient air quantities
~High static pressures.
