Technician Examination Advanced 100-
Question Practice Exam 2026 |
Questions & Answers with Detailed
Rationales | Complete Exam Prep &
Study Guide
1. A hydronic heating system has a circulator that is operating, but the remote
terminal units receive very little flow. The pump suction pressure is normal,
while the discharge pressure is substantially higher than expected. What is
the most likely cause?
A. Air entrainment at the expansion tank
B. Excessive system differential pressure
C. A partially closed or obstructed discharge-side valve
D. An undersized expansion tank
Answer: A partially closed or obstructed discharge-side valve
,Rationale: A restriction downstream of the circulator increases discharge
pressure while reducing actual system flow. An expansion tank problem or air
issue would not normally create this characteristic pressure differential.
2. When sizing a hydronic circulation pump for a closed-loop system, which
two primary parameters determine the required pump selection?
A. Boiler input and pipe material
B. Required flow rate and total dynamic head
C. Water temperature and expansion-tank volume
D. Pipe insulation thickness and boiler efficiency
Answer: Required flow rate and total dynamic head
Rationale: Pump selection is based primarily on the design flow rate and the
head loss the pump must overcome through piping, fittings, equipment, and
terminal devices.
3. A forced-air furnace has adequate gas pressure and ignition, but the flame
repeatedly shuts down shortly after ignition. Which component should be
checked first?
A. Blower capacitor
B. High-limit switch
C. Flame-sensing device and its electrical ground path
D. Return-air grille
Answer: Flame-sensing device and its electrical ground path
Rationale: A furnace that lights and then quickly drops the gas valve commonly
has a flame-proving problem. A contaminated sensor, poor grounding, or
defective flame-proving circuit can cause this condition.
4. A 120/240-volt single-phase motor draws excessive current on one branch
while the other measured voltage remains normal. What should be
investigated first?
,A. Refrigerant charge
B. Voltage imbalance, loose connections, or winding problems
C. Duct velocity
D. Boiler relief-valve pressure
Answer: Voltage imbalance, loose connections, or winding problems
Rationale: Unequal electrical conditions or deteriorated motor windings can
cause excessive current and overheating. Connections should be inspected and
voltage/current measurements compared under load.
5. What is the primary purpose of an expansion tank in a closed hydronic
heating system?
A. Increase boiler firing rate
B. Remove dissolved oxygen
C. Accommodate thermal expansion of the system fluid
D. Increase circulator speed
Answer: Accommodate thermal expansion of the system fluid
Rationale: Water expands as temperature increases. The expansion tank
provides a compressible volume that absorbs this expansion and helps control
system pressure.
6. A boiler operates normally at low load but repeatedly reaches high-limit
temperature before the building is adequately heated. Which condition is
most likely?
A. Excessive combustion air
B. Insufficient hydronic flow through the boiler or distribution system
C. Oversized expansion tank
D. Low outdoor humidity
Answer: Insufficient hydronic flow through the boiler or distribution system
, Rationale: If heat cannot be transported away from the boiler rapidly enough,
boiler temperature rises quickly and the high-limit control interrupts firing even
though the building still requires heat.
7. In a refrigerant circuit, a substantially higher-than-normal superheat with a
low suction pressure most commonly indicates:
A. Overfeeding of the evaporator
B. Insufficient refrigerant feed to the evaporator
C. Excessive condenser flooding
D. An oversized evaporator
Answer: Insufficient refrigerant feed to the evaporator
Rationale: High superheat means the refrigerant is becoming fully vaporized
early in the evaporator. A restricted metering device, low charge, or liquid-line
restriction can produce this condition.
8. A thermostatic expansion valve system has low superheat and a high
suction pressure. What condition should be suspected?
A. Starved evaporator
B. Excessive refrigerant feeding or an improperly adjusted/faulty expansion
valve
C. Severe liquid-line restriction
D. Completely blocked filter-drier
Answer: Excessive refrigerant feeding or an improperly adjusted/faulty
expansion valve
Rationale: Excessive refrigerant flow can cause low evaporator superheat and
elevated suction pressure because the evaporator is being overfed.
9. What is the principal purpose of a filter-drier installed in a refrigeration
system?
A. Increase compressor displacement
B. Remove moisture and contaminants from the refrigerant circuit