Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which tool is most commonly used to measure the electrical
resistance in a thermostat circuit?
A) Screwdriver
B) Hammer
C) Multimeter
D) Pliers
A multimeter measures resistance, voltage, and current, which is
essential for diagnosing thermostat circuits.
2. What is the purpose of a thermostat in an HVAC system?
A) To increase water pressure
B) To filter air
C) To regulate temperature
, D) To circulate coolant
A thermostat controls heating or cooling equipment to maintain a
set temperature.
3. A thermostat with a mercury switch is considered:
A) Digital
B) Analog
C) Smart
D) Wireless
Mercury switches operate mechanically, making the thermostat
analog.
4. What type of maintenance is essential to prevent thermostat
malfunction?
A) Painting
B) Cleaning contacts and checking wiring
C) Lubricating ducts
D) Replacing filters only
Regular cleaning and inspection prevent buildup and loose
connections that could cause inaccurate temperature readings.
5. If a thermostat is not turning on the HVAC system, the first thing a
technician should check is:
A) The air filter
B) Power supply to the thermostat
C) The refrigerant level
, D) Duct insulation
Without power, the thermostat cannot signal the system to operate.
6. What does the “anticipator” in a mechanical thermostat do?
A) Adjusts humidity
B) Prevents overshooting the set temperature
C) Measures airflow
D) Increases voltage
The anticipator provides a small heating current to shut the system
off at the right time.
7. Which type of thermostat is controlled via Wi-Fi or smartphone?
A) Mechanical
B) Smart
C) Mercury
D) Bimetallic
Smart thermostats allow remote temperature control and
programming via connected devices.
8. A thermostat labeled “SPDT” refers to:
A) Single Power Double Terminal
B) Single Pole Double Throw
C) Standard Pressure Device Type
D) Single Phase Device Toggle
SPDT switches have one input and two outputs, commonly used in
thermostats for switching heating or cooling circuits.
, 9. The main reason for calibrating a thermostat is to:
A) Increase airflow
B) Reduce humidity
C) Ensure accurate temperature control
D) Reduce energy usage only
Calibration ensures the thermostat turns on/off at the correct
temperature.
10. In a bimetallic strip thermostat, the strip bends because:
A) Different metals expand at different rates
B) Air pressure changes
C) Magnetic field interference
D) Current fluctuations
Bimetallic strips use two metals with different expansion rates to
mechanically operate the switch.
11. Which safety precaution is most important when servicing a
thermostat?
A) Wearing gloves only
B) Checking the filters
C) Turning off electrical power
D) Cleaning ducts first
Electrical power must be disconnected to avoid shocks when
servicing a thermostat.