GUIDE 2026
◉ A damaged section of double wall vent pipe is to be replaced with
a section produced by a different manufacturer: Answer: The
installer should check the new section for compatible locking joints.
◉ If too much primary air is used the flame will: Answer: Lift off the
burner.
◉ What is the problem when a flame on a high efficiency gas furnace
is burning primarily yellow: Answer: The flame is burning without
sufficient combustion air.
◉ The cause of a voltage reading across a closed contact in a 24V
control circuit is: Answer: Pitted or dirty contacts.
◉ The following are the first two checks typically made on an
electronic control: Answer: Presence of any on board transformer
voltage.
Proper output voltage.
◉ During a service call on a unit the technician finds that the wiring
diagram is missing from the access panel. The technician may begin
,troubleshooting by: Answer: Tracing the circuits either mentally or
on a sketch pad.
◉ The first check made for most electrical troubleshooting is a:
Answer: Voltage check of the supply line.
◉ The test to be used to check the wiring and connections to the
terminals of an energized blower motor is a: Answer: Voltage test.
◉ The following conditions exist in a circuit that supplies power to
three parallel loads. Answer: The total current in the circuit when
operating will be the sum of the currents through each load.
◉ To test the continuity of an internal overload protector in a single-
phase motor the motor: Answer: Must be cool.
◉ A control string is defined as two or more switch contacts
connected in a circuit, or set of circuits, to control a load. In order to
troubleshoot a load controlled by a control string, the technician
must first: Answer: Check for proper voltage applied across the load.
◉ When troubleshooting a blower motor circuit on a packaged
system, 244V is measured across the motor and no amperage is
measured: Answer: The likely problem with this system is an
internal overload device is open.
, ◉ The continuity through a de-energized relay coil is checked by
using what? Answer: Ohmmeter
◉ What is the industry accepted method for locating a suspected
natural gas leak? Answer: A soap solution.
◉ A customer has concerns about carbon monoxide (CO) in their
hone. Many of their reported symptoms indicate there may indeed
be a CO problem but on each trip the technician makes to check their
home the technician finds normal CO levels. Answer: CO detector
reader/recorder would be appropriate to use for determining if a
problem truly exists.
◉ Prior to performing an air balancing check of a newly installed
duct system: Answer: Dampers should be open completely in all
rooms.
◉ An external static check with a high reading indicates that the
blower is developing enough: Answer: RPM
◉ The following readings, are most appropriate for complete air
balancing report Answer: Total pressure
Static pressure
Outlet pressure