EPA Section 608 Technician Certification (Universal) — Questions and Answers

Question 1: What test is performed with a 'combustion analyzer' on a gas furnace?

Measuring flue gas composition (CO, CO2, O2, efficiency) to verify safe and efficient combustion (Correct answer)
Checking gas pressure at the manifold
Verifying igniter resistance
Measuring refrigerant combustion products in the heat exchanger

Correct answer: Measuring flue gas composition (CO, CO2, O2, efficiency) to verify safe and efficient combustion

A combustion analyzer measures flue gas composition including carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2), excess air, and calculates combustion efficiency. High CO indicates incomplete combustion (dangerous); efficiency readings guide burner adjustment.

Question 2: What does a capacitor do in an HVAC motor circuit?

Stores electrical energy to help start and run single-phase motors (Correct answer)
Reduces voltage to the motor during startup
Measures current draw for the motor protection circuit
Converts AC power to DC power for the control board

Correct answer: Stores electrical energy to help start and run single-phase motors

Capacitors store electrical energy and create a phase shift that provides starting torque and improves running efficiency in single-phase HVAC motors.

Question 3: What is a 'heat recovery' system in commercial HVAC and when is it most beneficial?

Capturing heat from exhaust air and using it to pre-condition incoming outdoor air, saving energy (Correct answer)
A heat pump system that recovers solar energy
Using waste heat from the building structure to reduce cooling loads
Recovering heat rejected by chillers for use in other building systems

Correct answer: Capturing heat from exhaust air and using it to pre-condition incoming outdoor air, saving energy

Heat recovery (via ERV or HRV) captures energy from exhaust air to pre-condition incoming outdoor air. ERVs transfer both heat and moisture; HRVs transfer heat only. Most beneficial in climates with large indoor/outdoor temperature differences and high ventilation requirements.

Question 4: What does ARI Standard 700 specify for reclaimed refrigerants?

Minimum purity levels refrigerant must meet before it can be resold (Correct answer)
Approved disposal methods for high-GWP refrigerants
Maximum cylinder fill weights for HFC refrigerants
Required recovery vacuum levels before opening a system

Correct answer: Minimum purity levels refrigerant must meet before it can be resold

ARI Standard 700 (now AHRI 700) establishes the purity specifications that reclaimed refrigerant must meet to be resold as 'like-new' quality.

Question 5: What does a low suction pressure reading typically indicate?

Overcharge of refrigerant
Restricted airflow over the evaporator or low refrigerant charge (Correct answer)
High outdoor ambient temperature
Faulty high-pressure switch

Correct answer: Restricted airflow over the evaporator or low refrigerant charge

Low suction pressure commonly indicates a low refrigerant charge, restricted metering device, or insufficient airflow across the evaporator coil.

Question 6: What communication error commonly causes a mini-split to display an 'E6' or similar error code?

Communication failure between indoor and outdoor units, often caused by wiring issues or incorrect wire connections (Correct answer)
Temperature sensor failure on the indoor unit
Refrigerant charge too low triggering a protection mode
Power supply voltage out of acceptable range

Correct answer: Communication failure between indoor and outdoor units, often caused by wiring issues or incorrect wire connections

Communication errors (often E6, E7, or similar codes) occur when the indoor and outdoor units cannot exchange data. Common causes: reversed or disconnected communication wires, damaged wire insulation causing shorts, or electrical interference. Always verify wiring polarity and continuity first.

Question 7: What is 'line set flushing' and when is it required for mini-split installation?

Flushing the line set with water to check for blockages
Pressure testing the line set with nitrogen before charging
Running refrigerant through the line set to pre-condition it
Removing old oil and contaminants from existing copper line sets when reusing them with a new mini-split system (Correct answer)

Correct answer: Removing old oil and contaminants from existing copper line sets when reusing them with a new mini-split system

Line set flushing uses a dedicated flushing agent (not refrigerant) to remove old oil, moisture, and contaminants from existing copper line sets. Required when reusing old line sets from a previous system, especially when switching refrigerant types or after a compressor burnout.

Question 8: What type of cylinder must be used when recovering refrigerant under EPA Section 608?

The original manufacturer's refrigerant cylinder
A stainless steel vacuum tank
A DOT-approved recovery cylinder that is properly color-coded and not filled above 80% capacity (Correct answer)
Any pressure vessel rated above 150 PSI

Correct answer: A DOT-approved recovery cylinder that is properly color-coded and not filled above 80% capacity

Recovered refrigerant must be stored in DOT-approved recovery cylinders (gray with yellow collar) and must not be filled above 80% of their capacity to allow for liquid expansion.

Question 9: What is the effect of 'air stratification' on coil performance in a large duct?

It only affects filter performance, not coil performance
Uneven air temperature and humidity distribution across the coil face reduces efficiency and may cause condensation problems (Correct answer)
It improves coil efficiency by creating turbulent flow
It has no effect if the coil is properly sized

Correct answer: Uneven air temperature and humidity distribution across the coil face reduces efficiency and may cause condensation problems

Air stratification (temperature/humidity layers in the airstream) causes uneven conditions across the coil face. Some portions may be oversaturated (causing moisture carryover) while others are underloaded, reducing overall efficiency and creating IAQ issues.

Question 10: During a gas furnace call for heat, the inducer motor starts but the ignitor never glows. Which component is most likely at fault?

Limit switch
Pressure switch (Correct answer)
Gas valve solenoid
Flame sensor

Correct answer: Pressure switch

If the pressure switch fails to close after the inducer starts, the control board will not energize the ignitor because it has not confirmed proper draft.

Question 11: What is the purpose of a 'nitrogen pressure test' on an HVAC system?

To flush oil from the refrigerant lines
To test the strength of the compressor
To pressurize the refrigerant circuit to check for leaks before charging with refrigerant (Correct answer)
To remove moisture from the refrigerant circuit

Correct answer: To pressurize the refrigerant circuit to check for leaks before charging with refrigerant

A nitrogen pressure test introduces dry nitrogen into the refrigerant circuit at a safe test pressure to check for leaks. Nitrogen is inert, dry, and inexpensive, making it ideal for leak testing. The system is pressurized and monitored with gauges — pressure drop indicates a leak.

Question 12: Under the EPA 608 program, which certification type covers small appliances (under 5 lbs of refrigerant)?

Universal
Type III
Type I (Correct answer)
Type II

Correct answer: Type I

Type I certification covers technicians who service small appliances containing 5 lbs or less of refrigerant, such as household refrigerators and window AC units.

Question 13: What is the purpose of a modulating gas valve in a high-efficiency furnace?

To shut off gas flow immediately if a flame failure is detected
To allow the furnace to switch between natural gas and propane fuels
To vary the gas flow rate so the furnace can operate at partial capacity to match heating demand (Correct answer)
To regulate gas pressure from the utility supply to burner pressure

Correct answer: To vary the gas flow rate so the furnace can operate at partial capacity to match heating demand

A modulating valve allows the furnace to fire at varying percentages of its rated capacity (e.g., 40–100%) rather than only full-on or full-off. This closely matches heat output to actual demand, improving comfort, efficiency, and reducing temperature swings.

Question 14: Which federal agency regulates the sale and use of refrigerants under Section 608?

DOT
EPA (Correct answer)
NIOSH
OSHA

Correct answer: EPA

The Environmental Protection Agency (EPA) administers and enforces Section 608 of the Clean Air Act, which governs refrigerant handling, recovery, and technician certification.

Question 15: What is a common indicator of a dirty condenser coil on a manifold gauge set?

Low suction pressure with low superheat
High head (discharge) pressure with normal subcooling (Correct answer)
High suction pressure with low superheat
Low subcooling with normal suction pressure

Correct answer: High head (discharge) pressure with normal subcooling

A dirty condenser coil restricts airflow, reducing heat rejection. This causes high discharge (head) pressure. Subcooling may be normal or slightly low because the issue is heat rejection, not refrigerant quantity. This distinguishes dirty condenser from overcharge (which increases both head pressure and subcooling).

Question 16: What does 'total equivalent length' mean when designing a duct system?

The actual straight duct length plus the equivalent straight-duct resistance of all fittings and transitions (Correct answer)
The maximum allowable duct run length before pressure drop becomes excessive
The actual measured length of all duct runs from supply to return
The total combined length of all supply and return duct branches

Correct answer: The actual straight duct length plus the equivalent straight-duct resistance of all fittings and transitions

Total equivalent length accounts for friction losses in both actual duct lengths and fittings by expressing fitting resistance as an equivalent length of straight duct.

Question 17: What is the role of a 'cooling tower' in a commercial HVAC system?

It is a large air handler unit mounted on the roof
It stores chilled water for peak demand periods
It rejects heat from chiller condenser water to the atmosphere through evaporative cooling (Correct answer)
It cools outdoor air before it enters the building

Correct answer: It rejects heat from chiller condenser water to the atmosphere through evaporative cooling

A cooling tower rejects heat from the chiller's condenser water loop to the atmosphere using evaporative cooling (water evaporation). Hot condenser water from the chiller is sprayed over fill media; evaporation cools the water before it returns to the chiller condenser.

Question 18: In commercial buildings, ASHRAE Standard 62.1 governs:

Electrical requirements for HVAC installations
Refrigerant safety classifications
Ventilation rates for acceptable indoor air quality (Correct answer)
Energy efficiency minimums for HVAC equipment

Correct answer: Ventilation rates for acceptable indoor air quality

ASHRAE 62.1 sets minimum ventilation rates for commercial buildings to ensure acceptable indoor air quality for occupants.

Question 19: What is the ODP (Ozone Depletion Potential) of R-410A?

0.00 (Correct answer)
0.50
0.05
1.00

Correct answer: 0.00

R-410A has an ODP of 0 because it contains no chlorine or bromine atoms, which are the elements that destroy stratospheric ozone. This is why it replaced R-22 (ODP = 0.05).

Question 20: A Building Automation System (BAS) is more commonly found in commercial buildings than residential because:

Residential buildings do not require energy management
Residential thermostats cannot be programmed
Commercial buildings have multiple HVAC zones and systems requiring centralized control (Correct answer)
BAS systems only work with three-phase electrical systems

Correct answer: Commercial buildings have multiple HVAC zones and systems requiring centralized control

BAS integrates control of multiple HVAC systems, lighting, and other building systems across many zones, which is impractical to manage manually in large commercial buildings.

Question 21: Which standard governs cybersecurity requirements for building automation and control network systems?

NFPA 72
ASHRAE 90.1
NIST SP 800-82 and ASHRAE Guideline 13 (Correct answer)
UL 864

Correct answer: NIST SP 800-82 and ASHRAE Guideline 13

NIST SP 800-82 and ASHRAE Guideline 13 address cybersecurity best practices for industrial and building control network systems.

Question 22: What is 'zoning' in HVAC systems and how does it differ between residential and commercial applications?

Residential zoning uses dampers and multiple thermostats in one system; commercial uses separate AHUs or VAV systems serving multiple zones (Correct answer)
Commercial zoning uses zone thermostats; residential uses VAV boxes
Zoning is only used in commercial buildings
Zoning refers to geographic service areas for HVAC contractors

Correct answer: Residential zoning uses dampers and multiple thermostats in one system; commercial uses separate AHUs or VAV systems serving multiple zones

Zoning divides a building into areas with independent temperature control. Residential zoning uses motorized dampers and a zone controller with multiple thermostats on one system. Commercial buildings use VAV systems, multiple AHUs, or fan coil units to independently control many zones.

Question 23: What is the ASHRAE refrigerant safety classification system based on?

Toxicity (A=lower, B=higher) and flammability (1=no flame, 2=lower, 3=higher) classes (Correct answer)
Ozone depletion potential and global warming potential
Pressure rating and temperature range only
Chemical composition and molecular weight

Correct answer: Toxicity (A=lower, B=higher) and flammability (1=no flame, 2=lower, 3=higher) classes

ASHRAE's refrigerant classification uses a two-character system: a letter for toxicity (A=lower, B=higher) and a number for flammability (1=none, 2L=lower, 2=higher, 3=highest).

Question 24: What is a key code difference between residential and commercial HVAC installations regarding refrigerant room requirements?

Commercial facilities with large refrigerant charges require mechanical equipment rooms with ventilation, refrigerant detectors, and emergency shutoffs per ASHRAE 15 (Correct answer)
Residential installations require dedicated equipment rooms; commercial does not
Both have identical installation requirements
Residential systems require refrigerant detectors; commercial does not

Correct answer: Commercial facilities with large refrigerant charges require mechanical equipment rooms with ventilation, refrigerant detectors, and emergency shutoffs per ASHRAE 15

ASHRAE Standard 15 (Safety Standard for Refrigeration Systems) requires mechanical equipment rooms for large refrigerant charges in commercial facilities, with ventilation systems, refrigerant leak detectors, emergency shutoffs, and occupancy sensors. Residential systems have much simpler requirements.

Question 25: What does a dual-capacitor (dual-run capacitor) contain and what does it power?

Two run capacitors in series to reduce voltage to the motors
A capacitor for the blower motor and one for the control transformer
Two separate capacitor sections in one housing: one for the compressor and one for the condenser fan motor (Correct answer)
A start capacitor and a run capacitor wired in parallel for the compressor only

Correct answer: Two separate capacitor sections in one housing: one for the compressor and one for the condenser fan motor

A dual-run capacitor contains two separate capacitor sections in one round or oval housing, with one section running the compressor and the other running the condenser fan motor.

Question 26: What is the purpose of a compressor hard start kit?

To start the compressor manually when the thermostat fails
To allow the compressor to start against a high-pressure difference
To reduce the starting voltage applied to the compressor
To provide extra starting torque using a start capacitor and potential relay when the compressor struggles to start (Correct answer)

Correct answer: To provide extra starting torque using a start capacitor and potential relay when the compressor struggles to start

A hard start kit adds a start capacitor and potential relay to boost starting torque for compressors that struggle to start, often due to voltage issues or worn motor windings.

Question 27: A customer reports that their ductless heat pump's heating capacity drops significantly when outdoor temperature falls below 35°F. This is MOST likely caused by:

A defective reversing valve sticking in cooling mode
The normal thermodynamic reduction in heat pump heating capacity at low outdoor temperatures (Correct answer)
A failed start capacitor on the outdoor fan motor
A refrigerant overcharge condition

Correct answer: The normal thermodynamic reduction in heat pump heating capacity at low outdoor temperatures

Heat pump heating capacity naturally decreases as outdoor temperature drops because less heat energy is available to absorb from cold outdoor air—this is normal operation, not a fault.

Question 28: A technician recovers R-134a from an automotive system into a recovery cylinder and wants to reuse this refrigerant in an HVAC system. What is the problem with this plan?

R-134a recovered from automotive systems contains PAG oil incompatible with HVAC systems using POE oil (Correct answer)
R-134a is not approved for use in stationary HVAC equipment by EPA
Automotive R-134a is a different grade than HVAC-grade R-134a
Recovery cylinders used for automotive refrigerant cannot be used for HVAC refrigerant

Correct answer: R-134a recovered from automotive systems contains PAG oil incompatible with HVAC systems using POE oil

Automotive systems use PAG oil which is immiscible with the POE oil used in most stationary HVAC systems, making cross-use problematic without reclamation.

Question 29: Which refrigerant has been the standard for new residential split systems since R-22 was phased out?

R-22
R-134a
R-410A (Correct answer)
R-407C

Correct answer: R-410A

R-410A replaced R-22 as the standard residential refrigerant after the EPA phased out R-22 production due to its ozone-depleting properties.

Question 30: A retail store with 10,000 sq ft requires HVAC. Compared to a home of the same square footage, the commercial space will likely need:

Less heating capacity only
The same cooling capacity
Less cooling capacity due to lower ceilings
More cooling capacity due to higher occupancy and lighting loads (Correct answer)

Correct answer: More cooling capacity due to higher occupancy and lighting loads

Commercial spaces have higher internal heat gains from occupants, lighting, equipment, and frequent door openings, requiring more cooling capacity per square foot.

Question 31: Duct leakage testing is required by energy codes primarily in:

New residential construction to verify duct system integrity (Correct answer)
Only buildings in Climate Zone 1 and 2
Any building using hydronic heating
Commercial buildings over 50,000 sq ft only

Correct answer: New residential construction to verify duct system integrity

Energy codes such as IECC require duct leakage testing in new residential construction to ensure systems perform as designed and minimize energy waste.

Question 32: What is the primary purpose of a mixing box or outside air damper on an air handling unit?

To prevent condensation on the supply duct
To balance supply air pressure between zones
To introduce a controlled amount of outdoor fresh air into the return air stream (Correct answer)
To mix hot and cold refrigerant streams

Correct answer: To introduce a controlled amount of outdoor fresh air into the return air stream

The outside air damper and mixing box introduce a controlled quantity of fresh outdoor air into the return air stream to meet ventilation requirements per ASHRAE standards.

Question 33: What does a filter-drier do in a refrigeration system?

Dries the condenser coil after rain
Removes moisture and contaminants from the refrigerant (Correct answer)
Filters compressor oil
Filters air entering the return duct

Correct answer: Removes moisture and contaminants from the refrigerant

A filter-drier removes moisture, acids, and debris from the refrigerant to protect system components from corrosion and blockage.

Question 34: Which BAS sequence of operation step typically follows the morning warm-up mode?

Freeze protection mode
Occupied mode (Correct answer)
Smoke purge mode
Night setback mode

Correct answer: Occupied mode

Morning warm-up pre-conditions the building before occupancy, after which the system transitions to occupied mode for normal operation.

Question 35: A customer reports their split system produces a musty odor whenever it runs. What is the most likely cause?

Cracked heat exchanger
Microbial growth on the evaporator coil or drain pan (Correct answer)
Refrigerant leak at the evaporator coil
Dirty condenser coil

Correct answer: Microbial growth on the evaporator coil or drain pan

Musty odors from HVAC systems are almost always caused by mold or bacteria growing on the wet evaporator coil surface or standing water in the drain pan.

Question 36: What is the purpose of a disconnect switch near an outdoor HVAC unit?

To provide a local means of de-energizing the unit for safe service work (Correct answer)
To protect the unit from voltage spikes and surges
To manually switch the system between heating and cooling modes
To connect the thermostat wiring to the outdoor unit

Correct answer: To provide a local means of de-energizing the unit for safe service work

The disconnect switch allows service technicians to safely de-energize the outdoor unit locally without going to the main electrical panel, as required by OSHA and NEC.

Question 37: What effect does moisture contamination have on an R-22 refrigerant system?

Improves lubrication of the compressor
Reacts with refrigerant and oil to form hydrochloric and hydrofluoric acids (Correct answer)
Has no significant effect
Raises evaporator pressure, reducing efficiency

Correct answer: Reacts with refrigerant and oil to form hydrochloric and hydrofluoric acids

Moisture reacts with refrigerant and oil at high temperatures to form hydrochloric and hydrofluoric acids. These acids corrode system components, damage the compressor, and cause copper plating.

Question 38: Which factor most significantly increases the design complexity of commercial HVAC versus residential?

Use of higher SEER equipment
Larger duct sizes required
Requirement for gas heating only
Multiple simultaneous occupancy zones with varying loads and schedules (Correct answer)

Correct answer: Multiple simultaneous occupancy zones with varying loads and schedules

Commercial buildings have diverse zones (conference rooms, server rooms, lobbies) with different occupancy schedules and load profiles, requiring complex zoning strategies.

Question 39: What is the function of a 'hard-start kit' (potential relay and start capacitor) on an air handler?

It provides backup power during voltage sags
It helps the blower motor start under high static pressure conditions
It is not used on air handlers — only on compressors (Correct answer)
It reduces starting current for the compressor in systems with long refrigerant lines

Correct answer: It is not used on air handlers — only on compressors

Hard-start kits (potential relay + start capacitor) are installed on compressors, not air handlers. They boost starting torque to help compressors start under high pressure differential or during low voltage conditions.

Question 40: What is the primary advantage of a ductless mini-split system over a central ducted system?

Elimination of duct losses (typically 20-30% of energy in ducted systems) and ability to serve spaces without existing ductwork (Correct answer)
Simpler refrigerant circuit with fewer components
Lower initial equipment cost
Higher cooling capacity per outdoor unit

Correct answer: Elimination of duct losses (typically 20-30% of energy in ducted systems) and ability to serve spaces without existing ductwork

Ductless mini-splits eliminate duct losses (typically 20-30% of system energy in leaky or poorly insulated ductwork), enabling direct zone-level conditioning. They are ideal for additions, converted spaces, and buildings where installing ductwork is impractical or too costly.

Question 41: A technician is recovering R-410A from a system and notices the recovery machine is running hot and slowing down. What is the most likely cause?

The recovery machine's internal filter is clogged
The recovery cylinder is almost full (Correct answer)
The ambient temperature is too low for R-410A recovery
The system still has refrigerant oil contaminating the circuit

Correct answer: The recovery cylinder is almost full

As a recovery cylinder fills, discharge pressure increases dramatically, causing the recovery machine to work harder, run hotter, and slow down.

Question 42: What is 'integration' in BAS, and why is it important for modern smart buildings?

Combining multiple BAS brands into one system without protocols
Integrating BAS with the utility meter for billing
Installing BAS in existing buildings with existing controls
Connecting HVAC, lighting, fire, security, and other building systems to share data and coordinate control through a common platform (Correct answer)

Correct answer: Connecting HVAC, lighting, fire, security, and other building systems to share data and coordinate control through a common platform

BAS integration connects multiple building systems (HVAC, lighting, access control, fire safety) to share data and coordinate operation. For example, fire alarm integration can override HVAC for smoke control; occupancy sensors from security can trigger HVAC setback.

Question 43: A variable air volume (VAV) box controlled by a BAS fails to open beyond 30% even at maximum cooling demand. What should be checked first?

Actuator wiring, travel limits, and calibration (Correct answer)
BACnet network topology
CO2 sensor accuracy
Chiller setpoint in the supervisory controller

Correct answer: Actuator wiring, travel limits, and calibration

When a VAV actuator doesn't fully travel, the first checks are wiring integrity, actuator calibration, and mechanical travel limit settings.

Question 44: Which condition requires a technician to evacuate a recovery cylinder before reusing it for the same refrigerant?

When the cylinder's last fill date was over 30 days ago
When the cylinder contains a different refrigerant or is contaminated (Correct answer)
When the cylinder has been stored outdoors
When the residual pressure is above atmospheric

Correct answer: When the cylinder contains a different refrigerant or is contaminated

A recovery cylinder must be evacuated before reuse if it contains a different refrigerant or any contamination to prevent cross-contamination.

Question 45: A technician measures superheat of 25°F on a TXV-equipped system. What does this indicate?

Filter-drier is saturated with moisture
Condenser fan motor is failing
TXV bulb may have lost its charge or TXV is underfeeding (Correct answer)
System is overcharged with refrigerant

Correct answer: TXV bulb may have lost its charge or TXV is underfeeding

High superheat on a TXV system typically points to a restricted or malfunctioning TXV that is underfeeding refrigerant to the evaporator.

Question 46: What is the purpose of 'minimum outdoor air' control in a commercial HVAC system?

To prevent equipment from operating in extremely cold weather
To maintain adequate ventilation for indoor air quality by ensuring a minimum quantity of outdoor air is always introduced (Correct answer)
To prevent the economizer from introducing too much outdoor air in hot weather
To control the exhaust air balance in the building

Correct answer: To maintain adequate ventilation for indoor air quality by ensuring a minimum quantity of outdoor air is always introduced

Minimum outdoor air ensures adequate ventilation per ASHRAE 62.1, regardless of cooling load. Even when economizer mode is not active or when cooling demand is low, a minimum quantity of outdoor air must be introduced to dilute indoor air pollutants and CO2.

Question 47: A residential mini-split system differs from a standard split system in that it:

Requires three-phase electrical power
Can only provide cooling, not heating
Uses water as a refrigerant
Delivers conditioned air directly to zones without ductwork (Correct answer)

Correct answer: Delivers conditioned air directly to zones without ductwork

Mini-split (ductless) systems connect an outdoor unit to one or more indoor air handlers mounted on walls or ceilings, eliminating the need for duct distribution.

Question 48: Commercial rooftop units (RTUs) differ from residential split systems primarily because RTUs:

Operate only in cooling mode
Require more frequent filter changes
House all components in a single cabinet on the roof (Correct answer)
Use R-410A refrigerant exclusively

Correct answer: House all components in a single cabinet on the roof

RTUs are self-contained units with all components (compressor, condenser, evaporator) in one cabinet mounted on the roof.

Question 49: What is the primary reason R-22 (HCFC) refrigerant is being phased out under the Montreal Protocol and US Clean Air Act?

It has poor energy efficiency compared to newer refrigerants
It is highly flammable and presents a fire hazard
It is highly toxic and dangerous to human health
It contains chlorine that destroys stratospheric ozone when released (Correct answer)

Correct answer: It contains chlorine that destroys stratospheric ozone when released

R-22 is an HCFC (hydrochlorofluorocarbon) that releases chlorine atoms when it breaks down in the stratosphere, catalytically destroying ozone molecules.

Question 50: What is MERV rating and why are commercial HVAC filters rated higher than typical residential filters?

MERV rates particle capture efficiency; commercial buildings have higher air quality standards, more occupants, and more pollutant sources requiring better filtration (Correct answer)
Higher MERV always means better energy efficiency
MERV only applies to commercial filters; residential uses FPR
MERV is the energy efficiency rating; commercial filters are larger but the same efficiency

Correct answer: MERV rates particle capture efficiency; commercial buildings have higher air quality standards, more occupants, and more pollutant sources requiring better filtration

MERV (Minimum Efficiency Reporting Value, ASHRAE 52.2) rates particle removal efficiency. Commercial buildings require higher MERV filters (MERV 8-14) due to more occupants, regulatory requirements (ASHRAE 62.1), and higher expectations for air quality, despite the increased pressure drop.

Question 51: What is an 'occupied/unoccupied' setback schedule in a BAS?

Temperature setpoint schedules that relax HVAC control setpoints during unoccupied periods to save energy (Correct answer)
A schedule that increases outdoor air during occupied hours
A fire alarm schedule that tests smoke detectors during unoccupied hours
A schedule that increases maintenance frequency during occupied hours

Correct answer: Temperature setpoint schedules that relax HVAC control setpoints during unoccupied periods to save energy

Setback scheduling programs the BAS to use relaxed temperature setpoints (higher cooling setpoint, lower heating setpoint) during unoccupied periods. This reduces HVAC energy consumption without sacrificing comfort during occupied hours.

Question 52: What is the primary purpose of an oil separator used during refrigerant recovery?

To filter acid from contaminated refrigerant
To regulate pressure entering the recovery machine
To separate compressor oil from refrigerant before it enters the recovery cylinder (Correct answer)
To remove moisture from the refrigerant before storage

Correct answer: To separate compressor oil from refrigerant before it enters the recovery cylinder

An oil separator prevents compressor oil from entering the recovery cylinder, keeping the refrigerant cleaner and reducing contamination.

Question 53: What is 'compressor superheat' and why is it important?

Heat added to liquid refrigerant before expansion
The discharge temperature of refrigerant leaving the compressor
The temperature rise of refrigerant vapor above its saturation point before entering the compressor (Correct answer)
Heat removed from refrigerant in the condenser

Correct answer: The temperature rise of refrigerant vapor above its saturation point before entering the compressor

Compressor superheat is the temperature of refrigerant vapor above its saturation point at the compressor inlet, ensuring only dry vapor enters to protect the compressor.

Question 54: When replacing an evaporator coil, why must the refrigerant circuit be properly evacuated before recharging?

To remove air and moisture that entered the system during the open coil replacement (Correct answer)
To remove excess oil that accumulated during the coil replacement
To clear error codes from the system control board
To reset the TXV superheat setting to factory defaults

Correct answer: To remove air and moisture that entered the system during the open coil replacement

Evacuation removes air and moisture that entered the open refrigerant system during coil replacement; moisture in the system can cause acid formation, freezing at the metering device, and compressor damage.

Question 55: In commercial HVAC design, what is the purpose of a smoke control system?

To filter cigarette smoke from tenant spaces
To detect refrigerant leaks in mechanical rooms
To provide makeup air for commercial kitchen exhaust
To manage airflow during a fire to protect egress paths and aid firefighting (Correct answer)

Correct answer: To manage airflow during a fire to protect egress paths and aid firefighting

Smoke control systems use HVAC equipment to pressurize stairwells and create smoke-free evacuation paths during a building fire.

Question 56: What does it mean when a gas furnace is described as 'direct vent' or 'sealed combustion'?

It requires no venting because combustion is complete
It draws combustion air from outside and vents exhaust gases directly to outside (Correct answer)
It uses the building's indoor air for combustion
It vents through an existing masonry chimney

Correct answer: It draws combustion air from outside and vents exhaust gases directly to outside

A direct vent/sealed combustion furnace uses a two-pipe system: one pipe brings outdoor combustion air in and another exhausts flue gases directly outside, without using indoor air.

Question 57: What is a 'hyper-heat' or 'cold climate' mini-split and what technology enables its low-temperature performance?

A system with supplemental electric resistance heat strips for very cold days
A mini-split with enhanced vapor injection (EVI) compressor technology that maintains rated capacity down to extreme outdoor temperatures (-13°F to -22°F) (Correct answer)
A system that uses R-32 refrigerant for better low-temperature performance
A system with larger outdoor coils for more surface area

Correct answer: A mini-split with enhanced vapor injection (EVI) compressor technology that maintains rated capacity down to extreme outdoor temperatures (-13°F to -22°F)

Cold climate (hyper-heat) mini-splits use Enhanced Vapor Injection (EVI) compressor technology that injects refrigerant vapor at an intermediate pressure into the compression process. This boosts heating capacity and maintains efficiency at outdoor temperatures as low as -13°F to -22°F (-25 to -30°C).

Question 58: What unit is used to measure the cooling capacity of HVAC equipment in the US?

BTU/hr or tons (Correct answer)
SEER
Horsepower (HP)
Kilowatts (kW)

Correct answer: BTU/hr or tons

Cooling capacity in the US is rated in BTU/hr or tons (1 ton = 12,000 BTU/hr), describing how much heat the system can remove per hour.

Question 59: What is the purpose of the defrost cycle in a heating-mode ductless mini-split system?

To melt frost accumulation on the outdoor coil that restricts airflow and heat transfer (Correct answer)
To reset the electronic expansion valve to its factory position
To purge moisture from the refrigerant circuit
To cool the indoor coil to prevent overheating during peak heating demand

Correct answer: To melt frost accumulation on the outdoor coil that restricts airflow and heat transfer

During heating operation in cold, humid conditions, frost builds on the outdoor coil; the defrost cycle temporarily reverses refrigerant flow to melt this frost and restore efficiency.

Question 60: What does a 'two-stage' recovery machine do differently than a single-stage unit?

It uses two condensers to lower discharge temperature
It uses two separate refrigerant circuits to increase speed
It recovers vapor first then switches to liquid recovery automatically (Correct answer)
It can recover two different refrigerants simultaneously

Correct answer: It recovers vapor first then switches to liquid recovery automatically

A two-stage recovery machine first removes vapor refrigerant, then automatically switches to remove liquid refrigerant for more complete recovery.

Question 61: What is the 'dual manifold' gauge technique for checking a system with two circuits (as in some commercial units)?

Using two refrigerant manifolds in parallel to speed up recovery
Connecting separate manifold gauge sets to each independent refrigerant circuit to compare pressures and diagnose imbalances (Correct answer)
Measuring both R-410A and R-22 pressures simultaneously
Using one gauge for high side and one for low side simultaneously on a single-circuit system

Correct answer: Connecting separate manifold gauge sets to each independent refrigerant circuit to compare pressures and diagnose imbalances

Some commercial units have two independent refrigerant circuits (two compressors, two coils). Using a separate gauge set on each circuit allows direct comparison of circuit pressures to identify if one circuit is underperforming, making multi-circuit diagnostics more efficient.

Question 62: What type of indoor unit is most commonly used in residential ductless mini-split installations?

Ceiling-concealed ducted unit
Wall-mounted high-wall unit (Correct answer)
Floor-mounted console unit
Ceiling cassette (four-way blow)

Correct answer: Wall-mounted high-wall unit

The wall-mounted high-wall unit is the most common residential ductless indoor unit. It mounts high on the wall, delivers conditioned air across the room with a wide sweep, is the lowest cost option, and is easiest to install. Ceiling cassettes and floor units are also available for specific applications.

Question 63: What happens to R-410A if it is charged as a liquid into the low side of a system?

It vaporizes instantly and enters normally
It improves system efficiency
It can cause compressor slugging and damage (Correct answer)
Nothing unusual — it's the standard charging method

Correct answer: It can cause compressor slugging and damage

R-410A is a zeotropic blend (though nearly azeotropic) and must be charged as a liquid to maintain the correct refrigerant composition. However, liquid refrigerant entering the compressor suction causes hydraulic slugging and compressor damage.

Question 64: What does a high-pressure lockout on a condensing unit protect against?

Low ambient temperature operation
Low refrigerant charge
Inadequate airflow across the evaporator coil
Excessively high discharge pressure that could damage the compressor (Correct answer)

Correct answer: Excessively high discharge pressure that could damage the compressor

A high-pressure lockout switch shuts down the unit when discharge pressure exceeds safe limits, preventing compressor damage from excessive head pressure.

Question 65: What is the primary cause of a humming or buzzing noise from an air handler blower motor?

Excessive airflow velocity
Dirty evaporator coil
Electrical issues such as capacitor failure or voltage imbalance (Correct answer)
Incorrect belt tension

Correct answer: Electrical issues such as capacitor failure or voltage imbalance

A humming or buzzing blower motor often indicates electrical problems like a failing start/run capacitor, loose wiring, or voltage imbalance causing abnormal electromagnetic operation.

Question 66: What does the AIM Act of 2020 regulate in the US HVAC industry?

Minimum energy efficiency standards for new HVAC equipment
Technician certification requirements for EPA Section 608
Air distribution and indoor air quality standards for HVAC systems
The phasedown of HFC refrigerants based on their GWP values (Correct answer)

Correct answer: The phasedown of HFC refrigerants based on their GWP values

The AIM (American Innovation and Manufacturing) Act of 2020 authorizes the EPA to phase down the production and consumption of HFC refrigerants by 85% over 15 years.

Question 67: What is the difference between a '2-pipe' and a '4-pipe' fan coil system in commercial buildings?

2-pipe systems use 2 fans; 4-pipe systems use 4 fans for better airflow
2-pipe systems serve 2 floors; 4-pipe systems serve 4 floors
4-pipe systems are more common in residential buildings
2-pipe systems heat or cool (not simultaneously); 4-pipe systems can heat and cool simultaneously in different zones (Correct answer)

Correct answer: 2-pipe systems heat or cool (not simultaneously); 4-pipe systems can heat and cool simultaneously in different zones

A 2-pipe system has one supply and one return pipe — it can either heat or cool the entire building at one time (seasonal changeover). A 4-pipe system has separate heating and cooling pipes, allowing simultaneous heating and cooling in different zones, ideal for buildings with mixed loads.

Question 68: How do you diagnose a bad start or run capacitor for a single-phase motor?

With a clamp-on ammeter measuring starting current only
By checking the capacitor's visual appearance — bulging or leaking indicates failure
By replacing it and observing if the problem resolves
Using a capacitor tester or digital multimeter in capacitance mode to compare measured µF to nameplate rating (Correct answer)

Correct answer: Using a capacitor tester or digital multimeter in capacitance mode to compare measured µF to nameplate rating

The definitive test for a capacitor is measuring its capacitance with a capacitor tester or DMM in µF mode and comparing to the nameplate rating. A reading more than 10% below rating indicates a weak capacitor requiring replacement. Visual inspection alone is not reliable.

Question 69: What is a 'sequence of operations' document in HVAC controls?

A list of control setpoints in order of priority
A wiring diagram for the control system
A written description of how an HVAC system and its controls should operate under all conditions (Correct answer)
A maintenance schedule for the HVAC system

Correct answer: A written description of how an HVAC system and its controls should operate under all conditions

A sequence of operations (SOO) is a narrative description of exactly how the HVAC system should function — startup, normal operation, setback, alarms, shutdown, and emergency modes. It's the primary reference for programming and commissioning DDC controls.

Question 70: What is the purpose of the inducer (draft) motor in a modern gas furnace?

To control the gas valve opening
To circulate conditioned air through the duct system
To mix combustion air with fuel before ignition
To pull combustion gases through the heat exchanger and vent them safely outdoors (Correct answer)

Correct answer: To pull combustion gases through the heat exchanger and vent them safely outdoors

The inducer motor creates a negative pressure draft that pulls combustion air through the burners and pushes flue gases safely out through the venting system.

Question 71: What is the primary function of an air handler unit (AHU) in an HVAC system?

Measure and control building humidity only
Generate refrigeration by compressing refrigerant
Control refrigerant flow to the outdoor unit
Condition and circulate air throughout the building (Correct answer)

Correct answer: Condition and circulate air throughout the building

An air handler unit (AHU) conditions and circulates air. It typically contains a blower, heating/cooling coils, filters, dampers, and controls to deliver conditioned air to occupied spaces.

Question 72: What is the significance of ARI-700 purity standards for refrigerants?

It sets the maximum GWP for new refrigerants
It specifies the minimum recovery efficiency of recovery machines
It establishes cylinder pressure ratings
It defines the purity specifications that reclaimed refrigerant must meet before resale (Correct answer)

Correct answer: It defines the purity specifications that reclaimed refrigerant must meet before resale

ARI Standard 700 (now AHRI 700) establishes the minimum purity specifications for reclaimed refrigerants sold as new. Reclaimed refrigerant meeting ARI-700 is considered equivalent to virgin refrigerant.

Question 73: When installing an air handler in a vertical upflow position, where should the evaporator coil be located?

On the side of the unit adjacent to the blower
At the top of the unit above the blower (Correct answer)
At the bottom of the unit below the blower
In a separate enclosure next to the blower

Correct answer: At the top of the unit above the blower

In a vertical upflow air handler, the blower is at the bottom and the evaporator coil is at the top so air flows upward through the coil.

Question 74: What refrigerant replaced R-22 (Freon) in most residential air conditioning systems in the US?

R-507
R-404A
R-410A (Correct answer)
R-134a

Correct answer: R-410A

R-410A became the standard replacement for R-22 in residential AC systems due to R-22's phase-out under the Clean Air Act.

Question 75: What communication standard is used by most modern BAS for Ethernet-based communication?

LonWorks FT-10
BACnet MS/TP over RS-485
Modbus TCP
BACnet/IP over Ethernet (Correct answer)

Correct answer: BACnet/IP over Ethernet

BACnet/IP (BACnet over Internet Protocol) uses standard Ethernet networking infrastructure, allowing BAS devices to communicate over the building's IT network. This enables remote access, integration with enterprise systems, and use of standard network infrastructure.

Question 76: A technician performs a nitrogen pressure test on a new refrigerant line set and observes pressure dropping from 300 psig to 285 psig over 15 minutes. What should the technician do?

Evacuate the line set immediately
Locate and repair the leak before proceeding (Correct answer)
Accept the reading as within tolerance and proceed to evacuation
Add refrigerant to compensate for the pressure drop

Correct answer: Locate and repair the leak before proceeding

Any pressure drop during a nitrogen leak test indicates a leak that must be found and repaired before the system is evacuated and charged.

Question 77: What is the purpose of 'commissioning' (Cx) in commercial HVAC, and what does it verify?

A systematic quality assurance process verifying that all HVAC systems are installed, programmed, and operating as specified by the design (Correct answer)
Installing HVAC equipment according to manufacturer instructions
A regulatory inspection required by state HVAC boards
Testing refrigerant charge after installation

Correct answer: A systematic quality assurance process verifying that all HVAC systems are installed, programmed, and operating as specified by the design

Commissioning is a quality assurance process that systematically verifies and documents that HVAC systems are designed, installed, and operating according to the Owner's Project Requirements (OPR) and design documents. It includes functional testing, control sequence verification, and performance testing.

Question 78: What is a 'DDC' controller in a building automation system?

Dynamic Damper Controller — controls VAV box dampers only
Direct Digital Control — uses microprocessors to control HVAC equipment based on sensor inputs (Correct answer)
Digital Data Compiler — stores sensor readings
Dual Duct Controller — manages dual duct HVAC systems

Correct answer: Direct Digital Control — uses microprocessors to control HVAC equipment based on sensor inputs

DDC (Direct Digital Control) uses microprocessor-based controllers to receive sensor inputs, execute control logic, and send output commands to HVAC equipment. DDC replaced pneumatic and analog electronic controls in modern systems.

Question 79: What is a 'multi-zone' mini-split system?

A system that can heat and cool multiple buildings simultaneously
Multiple mini-splits installed in the same zone for redundancy
A system with multiple outdoor units each serving one indoor unit
One outdoor unit connected to multiple indoor units (2-8 zones) via individual refrigerant branch piping (Correct answer)

Correct answer: One outdoor unit connected to multiple indoor units (2-8 zones) via individual refrigerant branch piping

A multi-zone (multi-split) system connects one outdoor unit to multiple indoor units (typically 2-8 units), each serving an independent zone with individual temperature control. Refrigerant branches from the outdoor unit to each indoor unit via a header or individual line sets.

Question 80: What is the primary difference between a residential split system and a commercial rooftop unit (RTU)?

Split systems are more energy efficient than RTUs
RTUs only provide cooling; split systems provide both heating and cooling
RTUs are self-contained (all components in one unit); split systems have separate indoor and outdoor units (Correct answer)
Split systems use R-22; RTUs use R-410A

Correct answer: RTUs are self-contained (all components in one unit); split systems have separate indoor and outdoor units

A commercial rooftop unit (RTU) is self-contained — compressor, condenser, evaporator, and controls are all in one outdoor unit. Residential split systems have a separate outdoor condensing unit and indoor air handler connected by refrigerant lines.

Question 81: Under EPA Section 608, technicians working on small appliances (systems with 5 lbs or less of refrigerant) must recover what percentage of refrigerant when using a non-self-contained recovery device?

60%
70%
80%
90% (Correct answer)

Correct answer: 90%

When using a non-self-contained recovery device on small appliances, technicians must recover 90% of the refrigerant.

Question 82: How do you diagnose a defective contactor on a condensing unit?

Measure the compressor amperage only
Check the contactor coil voltage and inspect contacts for pitting, burning, or failure to close/open properly (Correct answer)
Replace it without testing since contactors commonly fail
Check the capacitor — contactors rarely fail independently

Correct answer: Check the contactor coil voltage and inspect contacts for pitting, burning, or failure to close/open properly

Diagnose a contactor by: (1) verifying control voltage to the coil (24VAC), (2) checking for audible click when energized, (3) measuring voltage drop across closed contacts (should be near 0V), and (4) visually inspecting contacts for pitting, burning, or welding.

Question 83: Which type of heating system uses water heated by a boiler and distributed through pipes to radiators or radiant floor tubing?

Forced-air system
Hydronic system (Correct answer)
Heat pump system
Gravity furnace system

Correct answer: Hydronic system

Hydronic heating systems use hot water as the heat transfer medium. A boiler heats the water, which is then pumped through a closed-loop system to baseboard radiators, panel radiators, or radiant floor tubing to deliver heat.

Question 84: What does Manual J refer to in residential HVAC design?

A manual valve used on refrigerant service connections
The ASHRAE standard for commercial HVAC design
A required inspection journal for HVAC installations
The ACCA standard for residential heating and cooling load calculations (Correct answer)

Correct answer: The ACCA standard for residential heating and cooling load calculations

Manual J (published by ACCA) is the industry-standard method for calculating residential heating and cooling loads to properly size HVAC equipment.

Question 85: Which type of air handler configuration has the blower located downstream of the coil?

Horizontal side discharge
Draw-through (Correct answer)
Vertical upflow
Blow-through

Correct answer: Draw-through

In a draw-through configuration, the blower pulls air through the coil rather than pushing it, which is the most common arrangement.

Question 86: What is the correct way to determine if a recovery cylinder is safe to continue filling during active recovery?

Continue filling until the relief valve opens, then stop
Monitor the cylinder's pressure gauge and weight simultaneously against the refrigerant's maximum fill capacity (Correct answer)
Tap the cylinder with a wrench to hear if it sounds hollow or full
Use the cylinder until the recovery machine's discharge pressure exceeds 200 psig

Correct answer: Monitor the cylinder's pressure gauge and weight simultaneously against the refrigerant's maximum fill capacity

Safe fill level is determined by monitoring both pressure and weight—cylinders must not exceed 80% liquid fill by volume, verified by weight at the given temperature.

Question 87: What is a low ambient kit and when is it needed for air conditioning systems?

A low-voltage wiring kit for thermostat installation
A kit to operate AC systems in high-humidity environments
An insulation kit for refrigerant lines in cold climates
Controls that allow a cooling system to operate properly at low outdoor temperatures (Correct answer)

Correct answer: Controls that allow a cooling system to operate properly at low outdoor temperatures

A low ambient kit includes controls (head pressure controls, condenser fan cycling) that maintain proper condensing pressure when the system must operate in cool outdoor temperatures.

Question 88: When is it permissible to knowingly vent refrigerant under EPA Section 608?

Never — venting is always prohibited
When the system is being permanently retired
For refrigerants with ODP of zero only
For small releases during connection/disconnection of hoses (Correct answer)

Correct answer: For small releases during connection/disconnection of hoses

The EPA allows de minimis releases during normal connection and disconnection of service hoses, and for purging equipment of non-condensables that unavoidably contain refrigerant. Intentional venting is otherwise prohibited.

Question 89: Under EPA Section 608, who must be certified to purchase refrigerants in containers larger than 2 lbs?

Only master HVAC technicians
Any licensed contractor
Both EPA 608 and state-licensed technicians
EPA Section 608 certified technicians only (Correct answer)

Correct answer: EPA Section 608 certified technicians only

Since January 1, 2018, the EPA requires that technicians purchasing refrigerants in containers larger than 2 lbs be certified under Section 608, applying to all refrigerants including HFCs.

Question 90: What type of motor is most commonly used for HVAC variable-speed blowers in high-efficiency systems?

Universal motor
DC shunt motor
ECM (Electronically Commutated Motor) (Correct answer)
Single-phase induction motor

Correct answer: ECM (Electronically Commutated Motor)

ECM (Electronically Commutated Motor) blowers are brushless DC motors that can vary speed precisely and are 60-70% more efficient than standard PSC motors.

Question 91: What BACnet object type is used to represent a physical analog input such as a temperature sensor?

Analog Input (Correct answer)
Multi-State Output
Schedule
Binary Value

Correct answer: Analog Input

The BACnet Analog Input object type represents a physical analog measurement such as temperature or pressure.

Question 92: What is 'load calculation' software (like Manual J or HAP) used for?

Calculating refrigerant charge amounts
Calculating energy costs for building operations
Calculating ductwork sizes for air distribution
Calculating heating and cooling loads to properly size HVAC equipment for a specific building (Correct answer)

Correct answer: Calculating heating and cooling loads to properly size HVAC equipment for a specific building

Load calculation software (Manual J for residential, ASHRAE Handbook or HAP/Trace for commercial) calculates the heating and cooling loads for a specific building based on construction, climate, occupancy, and internal gains. Proper load calculations prevent over- or under-sizing equipment.

Question 93: What is the typical face velocity (air speed through coil face area) for a residential evaporator coil?

100-200 feet per minute
300-500 feet per minute (Correct answer)
600-900 feet per minute
1,000-1,500 feet per minute

Correct answer: 300-500 feet per minute

Residential evaporator coils are typically designed for 300-500 feet per minute face velocity, which balances heat transfer efficiency with acceptable airflow resistance and moisture carryover.

Question 94: What does a digital multimeter's 'uF' setting measure on a capacitor?

Micro-ohms of internal resistance
Micro-amperes of leakage current
Micro-volts of stored energy
Microfarads — the capacitance value of the capacitor (Correct answer)

Correct answer: Microfarads — the capacitance value of the capacitor

The uF (microfarad) setting on a multimeter measures a capacitor's capacitance value, allowing technicians to verify the capacitor meets its rated specification.

Question 95: What does 'negative building pressure' mean and why is it problematic?

Indoor air pressure is lower than outdoor air pressure, causing uncontrolled infiltration of unconditioned air (Correct answer)
Refrigerant pressure is below atmospheric pressure, causing air infiltration into the refrigerant circuit
The building has more exhaust than supply, causing doors to slam open
The return air system has higher pressure than the supply system

Correct answer: Indoor air pressure is lower than outdoor air pressure, causing uncontrolled infiltration of unconditioned air

Negative building pressure means the indoor air pressure is lower than outdoors, pulling in uncontrolled outside air (infiltration) through cracks and openings, which wastes energy and can cause moisture problems.

Question 96: What efficiency program rates commercial rooftop units above ASHRAE 90.1 minimums?

Energy Star for Commercial RTUs (Correct answer)
NAHB Green Building Program
EPA SmartWay
LEED certification

Correct answer: Energy Star for Commercial RTUs

Energy Star certifies commercial rooftop units that exceed ASHRAE 90.1 minimum efficiency standards by at least 10%. Energy Star RTUs can qualify buildings for LEED credits and demonstrate commitment to energy efficiency beyond code minimums.

Question 97: What is the coefficient of performance (COP) used to measure in HVAC?

The refrigerant charge level
The efficiency of a heating or cooling system (Correct answer)
The airflow rate through a duct system
The compressor discharge pressure

Correct answer: The efficiency of a heating or cooling system

COP is the ratio of useful heating or cooling output to the energy input, with a higher COP indicating a more efficient system.

Question 98: What type of ignition system has largely replaced standing pilot lights in modern gas furnaces?

Piezoelectric ignition
Electronic spark or hot surface ignition (Correct answer)
Thermocouple ignition
Glow plug ignition

Correct answer: Electronic spark or hot surface ignition

Modern furnaces use electronic ignition — either an intermittent spark igniter or a hot surface igniter (a silicon carbide or silicon nitride element that glows red-hot). These systems only activate at call for heat, eliminating the energy waste of a continuously burning pilot flame.

Question 99: A technician is sizing a mini-split for a sunroom with large south-facing glass walls. Which load calculation adjustment is most critical?

Using only floor area and ignoring the glass walls
Adding significant solar heat gain through the glass to the cooling load (Correct answer)
Subtracting BTUs for the glass insulation value
Reducing capacity because glass conducts heat away in winter

Correct answer: Adding significant solar heat gain through the glass to the cooling load

South-facing glass creates substantial solar heat gain that must be added to the cooling load calculation, often requiring a larger unit than square footage alone would suggest.

Question 100: What causes 'coil freeze-up' on an evaporator coil?

Overcharge of refrigerant causing high suction pressure
High outdoor ambient temperature reducing system capacity
Dirty condenser coil reducing heat rejection
Insufficient airflow or low refrigerant charge causing suction pressure to drop below freezing (Correct answer)

Correct answer: Insufficient airflow or low refrigerant charge causing suction pressure to drop below freezing

Coil freeze-up occurs when suction pressure drops low enough that coil surface temperature falls below 32°F. Causes include low airflow (dirty filter, failed blower) or low refrigerant charge, both of which reduce suction pressure.

EPA Section 608 Technician Certification (Universal)

The EPA Section 608 exam certifies HVAC technicians to legally purchase and handle refrigerants under federal environmental regulations. Universal certification covers all four sections: Core regulations, Type I small appliances, Type II medium/high-pressure systems, and Type III low-pressure systems.

100

Questions

120 min

Time Limit

70%

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