NATE AIR DISTRIBUTION QUESTIONS AND ANSWERS
What is the function of a transformer in a gas furnace? - Answers- It reduces line
voltage to control voltage.
On a call for heat, the thermostat energizes the __________ terminal - Answers- W
What is the function of the inducer in a gas furnace? - Answers- It brings in air for
combustion
Rollout limit switches are located in the __________. - Answers- Burner area
Which of the following statements is true regarding inshot burners? - Answers- They
require a seperate flame carryover channel.
A furnace with an AFUE of 90% or higher has ___________. - Answers- Both primary
and secondary heat exchangers.
For natural gas applications, an ideal line pressure is __________ - Answers- 7.0 in.
w.g.
For natural gas applications, the manifold pressure typically is set at _____________. -
Answers- 3.5 in. wg.
In a gas furnace application, "ESP" refers to the ___________. - Answers- resistance
to air flow in the supply and return ducts
What is the first step in the sequence of operation for a typical gas ignition system? -
Answers- The thermostat closes the R-W circuit
In a counterflow furnace, air passes from ___________. - Answers- The top to the
bottom of the furnace
Regarding combustion air requirements, a "confined space" is defined as a space who's
volume is ___________ per 1,000 BTUH of the combined input rating of all appliances
installed in that space. - Answers- Less than 50 ft.^3
Oil furnaces are vented with _________ venting material. - Answers- Type L
The purpose of a CAD cell in an oil furnace is to _______________. - Answers- Prove
the presence of flame
Normal CAD cell resistance is ______________ with flame present. - Answers- Less
than 1,600 Ohms
Oil furnaces typically are designed to burn _____________. - Answers- #2 fuel oil only
, The compressor changes refrigerant from a ________ to a _________. - Answers-
Low-pressure vapor, high-pressure vapor
In the condenser, refrigerant is changed from a _________ to a _________. - Answers-
High-pressure vapor, high-pressure liquid
The purpose of a metering device is to __________. - Answers- Create a pressure drop
A system that uses a TEV as a metering device _____________. - Answers- Must be
charged by the subcooling method
What is the state of the refrigerant leaving the evaporator? - Answers- Low-pressure
vapor
When you use the superheat method of verifying a system's refrigerant charge, adding
refrigerant should ____________. - Answers- Increase suction pressure and decrease
suction temperature
Why is it necessary to bleed fuel lines prior to burner operation? - Answers- To remove
air bubbles.
What tools are used to adjust an oil burner? - Answers- CO2 analyzer and smoke gun.
A properly adjusted oil burner should have a smoke test reading of _________. -
Answers- 0
Net stack temperature should be within the range of _____________ - Answers- 400 to
500 *F
If the measured temperature rise is ___________ than the range shown on the furnace
rating plate, you should __________ the blower speed. - Answers- Higher, increase
Air flow should be as close as possible to _________ per ton of air conditioning. -
Answers- 400 CFM
When you use the subcooling method of verifying a system's refrigerant charge, what
should you do if the measured subcooling is more than 3 *F lower than the
recommended subcooling value? - Answers- Add refrigerant in the vapor state.
Many "no cooling" calls are due to ________. - Answers- Neglected air filters
What type of refrigerant oil must be used with R-410A? - Answers- POE
What is the function of a transformer in a gas furnace? - Answers- It reduces line
voltage to control voltage.
On a call for heat, the thermostat energizes the __________ terminal - Answers- W
What is the function of the inducer in a gas furnace? - Answers- It brings in air for
combustion
Rollout limit switches are located in the __________. - Answers- Burner area
Which of the following statements is true regarding inshot burners? - Answers- They
require a seperate flame carryover channel.
A furnace with an AFUE of 90% or higher has ___________. - Answers- Both primary
and secondary heat exchangers.
For natural gas applications, an ideal line pressure is __________ - Answers- 7.0 in.
w.g.
For natural gas applications, the manifold pressure typically is set at _____________. -
Answers- 3.5 in. wg.
In a gas furnace application, "ESP" refers to the ___________. - Answers- resistance
to air flow in the supply and return ducts
What is the first step in the sequence of operation for a typical gas ignition system? -
Answers- The thermostat closes the R-W circuit
In a counterflow furnace, air passes from ___________. - Answers- The top to the
bottom of the furnace
Regarding combustion air requirements, a "confined space" is defined as a space who's
volume is ___________ per 1,000 BTUH of the combined input rating of all appliances
installed in that space. - Answers- Less than 50 ft.^3
Oil furnaces are vented with _________ venting material. - Answers- Type L
The purpose of a CAD cell in an oil furnace is to _______________. - Answers- Prove
the presence of flame
Normal CAD cell resistance is ______________ with flame present. - Answers- Less
than 1,600 Ohms
Oil furnaces typically are designed to burn _____________. - Answers- #2 fuel oil only
, The compressor changes refrigerant from a ________ to a _________. - Answers-
Low-pressure vapor, high-pressure vapor
In the condenser, refrigerant is changed from a _________ to a _________. - Answers-
High-pressure vapor, high-pressure liquid
The purpose of a metering device is to __________. - Answers- Create a pressure drop
A system that uses a TEV as a metering device _____________. - Answers- Must be
charged by the subcooling method
What is the state of the refrigerant leaving the evaporator? - Answers- Low-pressure
vapor
When you use the superheat method of verifying a system's refrigerant charge, adding
refrigerant should ____________. - Answers- Increase suction pressure and decrease
suction temperature
Why is it necessary to bleed fuel lines prior to burner operation? - Answers- To remove
air bubbles.
What tools are used to adjust an oil burner? - Answers- CO2 analyzer and smoke gun.
A properly adjusted oil burner should have a smoke test reading of _________. -
Answers- 0
Net stack temperature should be within the range of _____________ - Answers- 400 to
500 *F
If the measured temperature rise is ___________ than the range shown on the furnace
rating plate, you should __________ the blower speed. - Answers- Higher, increase
Air flow should be as close as possible to _________ per ton of air conditioning. -
Answers- 400 CFM
When you use the subcooling method of verifying a system's refrigerant charge, what
should you do if the measured subcooling is more than 3 *F lower than the
recommended subcooling value? - Answers- Add refrigerant in the vapor state.
Many "no cooling" calls are due to ________. - Answers- Neglected air filters
What type of refrigerant oil must be used with R-410A? - Answers- POE
