AND REVISED IN 2025-2026 DECEMBER
Metal ductwork tends to transmit noise and fan vibrations to
conditioned space. What connections are used to control it. -
ANSWER ->flex connectors
Duct wrap is used to insulate round metal ducts. What is the
approximate R-vale for "one inch" of this insulation? - ANSWER
->R = 3
A Category I natural gas furnace has a typical air temperature
rise of: - ANSWER ->40 F - 70 F
80,000 BTU gas furnace with a 3-ton cooling system and the fan
motor 1/3 HP @ 120 VAC. What size conductor would be used -
ANSWER ->12 - 14 AWG
A GFCI circuit breaker detects: - ANSWER ->Current leaks to
ground
Furnace makes a loud bang upon ignition. The gas pressure and
finds 3.2 in. WC at the manifold. You should: - ANSWER ->check
supply gas pressure
How much current does a typical flame sensor produce? -
ANSWER ->1 - 30 microamps
,A typical vent stack temperature on a NATURAL DRAFT furnace
is: - ANSWER ->350 F - 450 F
A 2-year old gas furnace will not light. The furnace locks out
trying to light. The gas valve reads 19 VAC you conclude. -
ANSWER ->transformer could be faulty
The pilot assembly orifice of a spark ignition furnace is
completely clogged. The technician should: - ANSWER ->replace
it
Carbon monoxide is dangerous. What percentage of CO is
acceptable in a sample of the flue gas? - ANSWER ->.04%
a 5 year old natural gas furnace. The main burner lights and the
flame wavers after 60 sec. The technician suspects: - ANSWER -
>a faulty heat exchanger
The main burners light, but the spark igniter keeps going. The
blower fan comes on and the burner goes out. Why? - ANSWER
->ignition board
The proper instrument for calculating carbon dioxide in flue gas
is a: - ANSWER ->combustion analyzer
If voltage is applied across two speed terminals on a fan motor,
the motor will: - ANSWER ->short out/burn out
, The maximum external static pressure on a typical gas furnace
blower system is: - ANSWER ->.2 - .6 in. WC
Induce draft furnaces have a vent safety switch that should
open at ...? - ANSWER ->140*F
Thermostat wire comes in two standard gauges - ANSWER ->18
and 16 AWG
A gas valve with 100% shut off means: - ANSWER ->Gas to a
pilot and manifold is shut-off
A gas furnace has an electronic control board. How is the fan
cycled during heating? - ANSWER ->time
A primary cause of burner "flashback" is: - ANSWER ->Low
manifold pressure
The reason for a crossover on a gas burner is to - ANSWER -
>Provide smooth lighting of all burners
A technician need to run thermostat wire 75 feet. To avoid a
voltage drop, the technician should use: - ANSWER -># 16 AWG
A gas furnace has an induced draft fan. Which switch must
operate properly before ignition sequence starts? - ANSWER -
>differential air pressure
You read 0 ohms between the common and low speed wires on
a 120 VAC furnace motor. You determine the winding is: -
ANSWER ->shorted
Metal ductwork tends to transmit noise and fan vibrations to
conditioned space. What connections are used to control it. -
ANSWER ->flex connectors
Duct wrap is used to insulate round metal ducts. What is the
approximate R-vale for "one inch" of this insulation? - ANSWER
->R = 3
A Category I natural gas furnace has a typical air temperature
rise of: - ANSWER ->40 F - 70 F
80,000 BTU gas furnace with a 3-ton cooling system and the fan
motor 1/3 HP @ 120 VAC. What size conductor would be used -
ANSWER ->12 - 14 AWG
A GFCI circuit breaker detects: - ANSWER ->Current leaks to
ground
Furnace makes a loud bang upon ignition. The gas pressure and
finds 3.2 in. WC at the manifold. You should: - ANSWER ->check
supply gas pressure
How much current does a typical flame sensor produce? -
ANSWER ->1 - 30 microamps
,A typical vent stack temperature on a NATURAL DRAFT furnace
is: - ANSWER ->350 F - 450 F
A 2-year old gas furnace will not light. The furnace locks out
trying to light. The gas valve reads 19 VAC you conclude. -
ANSWER ->transformer could be faulty
The pilot assembly orifice of a spark ignition furnace is
completely clogged. The technician should: - ANSWER ->replace
it
Carbon monoxide is dangerous. What percentage of CO is
acceptable in a sample of the flue gas? - ANSWER ->.04%
a 5 year old natural gas furnace. The main burner lights and the
flame wavers after 60 sec. The technician suspects: - ANSWER -
>a faulty heat exchanger
The main burners light, but the spark igniter keeps going. The
blower fan comes on and the burner goes out. Why? - ANSWER
->ignition board
The proper instrument for calculating carbon dioxide in flue gas
is a: - ANSWER ->combustion analyzer
If voltage is applied across two speed terminals on a fan motor,
the motor will: - ANSWER ->short out/burn out
, The maximum external static pressure on a typical gas furnace
blower system is: - ANSWER ->.2 - .6 in. WC
Induce draft furnaces have a vent safety switch that should
open at ...? - ANSWER ->140*F
Thermostat wire comes in two standard gauges - ANSWER ->18
and 16 AWG
A gas valve with 100% shut off means: - ANSWER ->Gas to a
pilot and manifold is shut-off
A gas furnace has an electronic control board. How is the fan
cycled during heating? - ANSWER ->time
A primary cause of burner "flashback" is: - ANSWER ->Low
manifold pressure
The reason for a crossover on a gas burner is to - ANSWER -
>Provide smooth lighting of all burners
A technician need to run thermostat wire 75 feet. To avoid a
voltage drop, the technician should use: - ANSWER -># 16 AWG
A gas furnace has an induced draft fan. Which switch must
operate properly before ignition sequence starts? - ANSWER -
>differential air pressure
You read 0 ohms between the common and low speed wires on
a 120 VAC furnace motor. You determine the winding is: -
ANSWER ->shorted
