Nate Gas Furnace Service Exam Questions
With Correct Answers
What precautions, if any, must be taken when installing a gas furnace on
| | | | | | | | | | | |
a wooden platform in an attic? - CORRECT ANSWER✔✔-Use a zero-
| | | | | | | | | | |
clearance furnace or add a non-combustible base
| | | | | |
A vent connector should have a as few elbows and joints as possible to:
| | | | | | | | | | | | |
- CORRECT ANSWER✔✔-Reduce resistance of flue gases
| | | | | | |
The gas control valve may be damaged if exposed to an inlet pressure
| | | | | | | | | | | | |
above - CORRECT ANSWER✔✔-14in wc
| | | |
To which thermostat is leveling the most critical: - CORRECT
| | | | | | | | | |
ANSWER✔✔-Mercury Bulb |
Which of the following is a reason for the thermostat to short cycle a
| | | | | | | | | | | | | |
gas furnace - CORRECT ANSWER✔✔-A system that is oversized for the
| | | | | | | | | | |
load
,When a thermocouple pilot flame is lost on a standing pilot gas furnace,
| | | | | | | | | | | | |
the primary component which shuts off gas flow to the main burner is: -
| | | | | | | | | | | | | |
CORRECT ANSWER✔✔-Pilot solenoid | |
The most important consideration when working on a gas furnace with
| | | | | | | | | | |
ribbon type insertion burners is - CORRECT ANSWER✔✔-The individual
| | | | | | | | |
burners must be mounted in correct alignment
| | | | | |
Primary air is mixed with the gas within the - CORRECT ANSWER✔✔-
| | | | | | | | | | |
Venturi or throat of the burner
| | | | |
An intermittent pilot gas furnace is one in which a - CORRECT
| | | | | | | | | | | |
ANSWER✔✔-Pilot is lit on every call for heat | | | | | | |
The pressure reading on a monometer is expressed in inches of -
| | | | | | | | | | | |
CORRECT ANSWER✔✔-Water |
How mush of the end of the thermocouple should be enveloped by the
| | | | | | | | | | | | |
pilot flame - CORRECT ANSWER✔✔-3/8 to ½ inch
| | | | | | |
The LP gas manifold pressure is commonly - CORRECT ANSWER✔✔-10
| | | | | | | | | |
to 11in wc
| |
,A thermocouple system usually generates its own control circuit voltage
| | | | | | | | | |
of - CORRECT ANSWER✔✔-750mv
| | |
On a single stage combination gas valve with a thermocouple flame
| | | | | | | | | | |
proving circuit, the main burner gas flow is - CORRECT ANSWER✔✔-In
| | | | | | | | | | |
series with the pilot gas valve | | | | |
What do the initials "A.F.U.E" represent - CORRECT ANSWER✔✔-Annual
| | | | | | | |
Fuel Utilization Efficiency
| | |
A technician measures the return air temperature of a 100,000 btuh
| | | | | | | | | | |
output gas furnace to be 65 F and the supply side air temperature is
| | | | | | | | | | | | | |
135F What is the CFM - CORRECT ANSWER✔✔-135-65=70TD
| | | | | | |
70TD x 1.08 = 75.6 | | | |
100,000/75.6 = 13,227CFM | |
A furnace is inoperative because of a failure in the ignition sequence of
| | | | | | | | | | | | |
the flame proving stage. To check the flame proving circuit the
| | | | | | | | | | |
technician would connect a: - CORRECT ANSWER✔✔-Microammeter set
| | | | | | |
to DC microamps in the flame rod circuit and operate the furnace
| | | | | | | | | | | |
A flame on a high efficiency gas furnace is burning primarily yellow.
| | | | | | | | | | | |
What, if anything is the problem in this furnace - CORRECT
| | | | | | | | | | |
ANSWER✔✔-The flame is burning without sufficient combustion air | | | | | | |
, A typical four-way multi-positional gas furnace is converted from up-
| | | | | | | | |
flow to downflow by - CORRECT ANSWER✔✔-Turning the furnace
| | | | | | | | |
upside down with specified alterations
| | | |
In the sequence of operation of an induced draft, intermittent pilot gas
| | | | | | | | | | | |
furnace, the induced draft motor starts - CORRECT ANSWER✔✔-When
| | | | | | | | |
the thermostat calls for heat
| | | |
A gas furnace with a standing pilot uses a flame switch for proving pilot
| | | | | | | | | | | | | |
flame. What type of signal is generated by such a flame prover -
| | | | | | | | | | | | |
CORRECT ANSWER✔✔-NO Signal is generated by a flame switch, but
| | | | | | | | | |
the flame sensor
| |
Which of the following components is considered a fire protection
| | | | | | | | | |
device on a gas furnace - CORRECT ANSWER✔✔-Roll out switch
| | | | | | | | |
With a non-direct vented furnace located in a what are the
| | | | | | | | | | |
requirements for the space to qualify as an unconfined space - CORRECT | | | | | | | | | | |
ANSWER✔✔-At least 50 ft3 of air volume for every 1000 btuh of all the
| | | | | | | | | | | | | | |
combustion appliances in the space | | | |
A technician is installing a system for a condensing gas furnace. The
| | | | | | | | | | | |
furnace is several feet from a gas water heater. Under what conditions,
| | | | | | | | | | | |
if any, may the technician route the exhaust of the furnace into the
| | | | | | | | | | | | |
With Correct Answers
What precautions, if any, must be taken when installing a gas furnace on
| | | | | | | | | | | |
a wooden platform in an attic? - CORRECT ANSWER✔✔-Use a zero-
| | | | | | | | | | |
clearance furnace or add a non-combustible base
| | | | | |
A vent connector should have a as few elbows and joints as possible to:
| | | | | | | | | | | | |
- CORRECT ANSWER✔✔-Reduce resistance of flue gases
| | | | | | |
The gas control valve may be damaged if exposed to an inlet pressure
| | | | | | | | | | | | |
above - CORRECT ANSWER✔✔-14in wc
| | | |
To which thermostat is leveling the most critical: - CORRECT
| | | | | | | | | |
ANSWER✔✔-Mercury Bulb |
Which of the following is a reason for the thermostat to short cycle a
| | | | | | | | | | | | | |
gas furnace - CORRECT ANSWER✔✔-A system that is oversized for the
| | | | | | | | | | |
load
,When a thermocouple pilot flame is lost on a standing pilot gas furnace,
| | | | | | | | | | | | |
the primary component which shuts off gas flow to the main burner is: -
| | | | | | | | | | | | | |
CORRECT ANSWER✔✔-Pilot solenoid | |
The most important consideration when working on a gas furnace with
| | | | | | | | | | |
ribbon type insertion burners is - CORRECT ANSWER✔✔-The individual
| | | | | | | | |
burners must be mounted in correct alignment
| | | | | |
Primary air is mixed with the gas within the - CORRECT ANSWER✔✔-
| | | | | | | | | | |
Venturi or throat of the burner
| | | | |
An intermittent pilot gas furnace is one in which a - CORRECT
| | | | | | | | | | | |
ANSWER✔✔-Pilot is lit on every call for heat | | | | | | |
The pressure reading on a monometer is expressed in inches of -
| | | | | | | | | | | |
CORRECT ANSWER✔✔-Water |
How mush of the end of the thermocouple should be enveloped by the
| | | | | | | | | | | | |
pilot flame - CORRECT ANSWER✔✔-3/8 to ½ inch
| | | | | | |
The LP gas manifold pressure is commonly - CORRECT ANSWER✔✔-10
| | | | | | | | | |
to 11in wc
| |
,A thermocouple system usually generates its own control circuit voltage
| | | | | | | | | |
of - CORRECT ANSWER✔✔-750mv
| | |
On a single stage combination gas valve with a thermocouple flame
| | | | | | | | | | |
proving circuit, the main burner gas flow is - CORRECT ANSWER✔✔-In
| | | | | | | | | | |
series with the pilot gas valve | | | | |
What do the initials "A.F.U.E" represent - CORRECT ANSWER✔✔-Annual
| | | | | | | |
Fuel Utilization Efficiency
| | |
A technician measures the return air temperature of a 100,000 btuh
| | | | | | | | | | |
output gas furnace to be 65 F and the supply side air temperature is
| | | | | | | | | | | | | |
135F What is the CFM - CORRECT ANSWER✔✔-135-65=70TD
| | | | | | |
70TD x 1.08 = 75.6 | | | |
100,000/75.6 = 13,227CFM | |
A furnace is inoperative because of a failure in the ignition sequence of
| | | | | | | | | | | | |
the flame proving stage. To check the flame proving circuit the
| | | | | | | | | | |
technician would connect a: - CORRECT ANSWER✔✔-Microammeter set
| | | | | | |
to DC microamps in the flame rod circuit and operate the furnace
| | | | | | | | | | | |
A flame on a high efficiency gas furnace is burning primarily yellow.
| | | | | | | | | | | |
What, if anything is the problem in this furnace - CORRECT
| | | | | | | | | | |
ANSWER✔✔-The flame is burning without sufficient combustion air | | | | | | |
, A typical four-way multi-positional gas furnace is converted from up-
| | | | | | | | |
flow to downflow by - CORRECT ANSWER✔✔-Turning the furnace
| | | | | | | | |
upside down with specified alterations
| | | |
In the sequence of operation of an induced draft, intermittent pilot gas
| | | | | | | | | | | |
furnace, the induced draft motor starts - CORRECT ANSWER✔✔-When
| | | | | | | | |
the thermostat calls for heat
| | | |
A gas furnace with a standing pilot uses a flame switch for proving pilot
| | | | | | | | | | | | | |
flame. What type of signal is generated by such a flame prover -
| | | | | | | | | | | | |
CORRECT ANSWER✔✔-NO Signal is generated by a flame switch, but
| | | | | | | | | |
the flame sensor
| |
Which of the following components is considered a fire protection
| | | | | | | | | |
device on a gas furnace - CORRECT ANSWER✔✔-Roll out switch
| | | | | | | | |
With a non-direct vented furnace located in a what are the
| | | | | | | | | | |
requirements for the space to qualify as an unconfined space - CORRECT | | | | | | | | | | |
ANSWER✔✔-At least 50 ft3 of air volume for every 1000 btuh of all the
| | | | | | | | | | | | | | |
combustion appliances in the space | | | |
A technician is installing a system for a condensing gas furnace. The
| | | | | | | | | | | |
furnace is several feet from a gas water heater. Under what conditions,
| | | | | | | | | | | |
if any, may the technician route the exhaust of the furnace into the
| | | | | | | | | | | | |
