Maryland HVAC Masters Practice Test

These questions are part of the practice quiz. Start practicing

• Explain the difference between a one-pipe and two-pipe hydronic heating system.
• Which of the following is a piping material used for gas piping in residential installations?
• When a duct system is not buried or encased, how far above the ground must it be installed?
• Define duct static pressure and explain why it must be within design values.
• What does venting orientation refer to, and why is it important?
• If refrigerant piping surface temperatures drop below the dew point, what action is recommended?
• A duct blower performance test is primarily used to verify:
• What does mfd stand for in capacitor specifications?
• What is the maximum allowable length for a flexible duct connector?
• A boiler shall have an unobstructed passageway of how many inches around all sides?
• An insulation that has absorbed moisture ___________.
• Which of the following options lists the three basic methods of heat transfer used in HVAC design?
• What is the maximum system design pressure for a hot water heating system?
• The purpose of a suction accumulator is ________.
• The height requirement for refrigerant piping applies unless the piping is located against the ceiling.
• What is the minimum gauge thickness for a 16-inch galvanized duct in a residential heating system?
• A 2000 sq. ft. Type II dry-cleaning system shall be provided with an exhaust no less than how many CFM?
• Which testing method confirms proper duct leakage under static pressure?
• What is the difference between AFUE and HSPF ratings?
• A high-pressure boiler shall have a shutoff valve in ____________.
• A connector to a chimney flue shall be at least how many inches above the lowest portion of the interior of the flue?
• Without a roof guard, the rooftop condenser must be set back from the edge by at least how many feet?
• Why is refrigerant charging adjusted after initial start-up?
• Which action is part of EPA-compliant refrigerant leak management?
• What is the purpose of a vent stack and venting clearances for gas appliances?
• When installing an exhaust duct for a downflow domestic range hood, which component is required?
• Which minimum vertical clearance above the floor is required for a heater installed in a public garage?
• The mechanical ventilation for a crawl space of 3,000 square feet is
• What is the typical purpose of an air handler in an HVAC system?
• A ___________ is used to measure relative humidity by comparing wet/dry bulb temperatures.
• What is air balancing and why is it important?
• In HVAC controls, a device that responds to humidity and can control a system is a
• If a boiler requires a minimum clearance of 3 feet to the ceiling, how many inches is that clearance?
• Clothes dryer exhaust exceeding what CFM requires makeup air?
• A control circuit in HVAC equipment is often powered through an isolation transformer to limit the voltage to a maximum of ______ volts.
• A 14-inch gas vent protruding through a roof and located 8 feet from a vertical wall must terminate not less than how many feet above the roof?
• What is the typical operating principle of a heat pump?
• What combination of material will reduce the clearance of an unlisted residential fired furnace from 18" to 6"?
• If the hot water supply temperature is 170 and the return temperature is 150, does this meet the required delta-T of at least 20 degrees?
• Which is not one of the three basic heat transfer methods?
• Which distance requirement applies to outside air exhaust openings relative to lot lines on the same lot?
• In a water source heat pump, the reversing valve controls which refrigerant state?
• Which Maryland agency licenses HVAC contractors and administers the HVAC Master exam?
• Makeup air is required when a clothes dryer exhaust exceeds which threshold?
• Backdrafting can occur when venting orientation is incorrect; what hazard does this create?
• What is the function of a low-water cut-off in a boiler system?
• The minimum room volume multiplier for boilers not listed for closet or alcove installation is 16 times the boiler volume. If the boiler volume is 1 cubic foot, the minimum room volume is at least how many cubic feet?
• If a circuit has 120 volts and 30 ohms resistance, the current is ______ amperes.
• What is the primary purpose of an accumulator in a heat pump system?
• What is the primary purpose of a backdraft damper in an exhaust system?
• A ventilation supply system shall deliver the required rate of supply air within an occupied space minimum of __________ above the floor.
• What is the maximum ventilation rate for a two-car residential garage?
• A dielectric fitting is used in piping systems to connect different metals.
• Which instrument measures electrical power?
• A safety belt lanyard shall be a minimum of ½ inch nylon, or equivalent, with a maximum length to provide for a fall of no greater than how many feet?
• What is the minimum distance from the edge for a roof-mounted refrigeration condenser without a roof guard?
• The HVAC Master exam in Maryland primarily covers which three code families?
• When may reclaimed refrigerant be reused in a different owner's equipment?
• Name a refrigerant commonly used in modern residential systems today.
• In Maryland, carbon monoxide detectors are typically required in new dwellings under which conditions?
• Which of the following materials can be used on oil piping for a residential installation?
• Why are direct-vent and sealed combustion appliances important for indoor air quality?
• What is the maximum control volts with isolation transformer?
• A fuel fired boiler that is not listed for closet or alcove installation shall be installed in rooms having a volume at least ________ times the total volume of the boiler.
• A plenum duct liner shall have a maximum smoke index of
• For IMC metallic ducts installed in/under concrete, which option is not a required compliance?
• What is the primary function of the main disconnect in an electrical HVAC installation?
• A duct that has an operating temperature of 150 deg F shall be insulated to limit the exposed surface temperature to how many degrees Fahrenheit?
• Down-pipe support material must not promote:
• A heater installed in a public garage must be installed a minimum distance above the floor of how many feet?
• What is the minimum working space clearance required on the sides of a central furnace located within compartments or alcoves?
• What is the slope of a commercial grease duct that runs 80 feet long?
• Refrigerant piping that crosses an open space that affords passageway in any building shall not be less than ______ above the floor unless the piping is located against the ceiling of such space.
• A liquid is considered flammable if it has a flash point below ______ degrees and has a vapor pressure not exceeding 50 psia.
• The minimum height above finish ground level for an exit terminal adjacent to public walkways in a mechanical draft system is at least how many feet?
• What is the function of a combustion air calculation?
• Maximum vertical spacing for steel pipe is ___________.
• What is the purpose of a manometer or digital manometer in gas piping?
• What is "superheat" and why is it important in HVAC refrigerant systems?
• IFGC stands for which code?
• A fuel fired warm air heater is installed in a residential garage. There is no protection from vehicle impact. The ignition source of the heater must have a minimum ground clearance of ____________.
• Which unit is used to measure static pressure in a central HVAC duct system?
• Define 'static pressure' in a central HVAC duct system.
• A 400 square foot machine room with 3 people requires how many CFM of ventilation?
• The required opening size for equipment-access rooms measuring 36 inches by 80 inches is which of the following?
• For a mechanical draft system, the exit terminal adjacent to public walkways shall be no less than how many feet above finish ground level?
• External equalizing line should be installed downstream of the thermostatic expansion valve at?
• What is the primary reason to perform a system commissioning check after installation?
• What is the role of a condensate drain in gas-fired boilers and high-efficiency furnaces?
• Which device is used to verify that the combustion blower is operating, and is connected to the damper system?
• Flexible air duct connections may pass through which of the following?
• What is the function of a zone control system?
• In Maryland, when performing gas piping installation above a certain pressure, what is required?
• An 18" high-heat metal chimney shall have a minimum sheet steel thickness of ____________.
• Commercial appliance exhaust outlets that terminate above roof shall have the discharge opening located not less than how many inches above the roof surface?
• A possible cause of a compressor running continuously is
• Which testing method is commonly used to validate gas piping leak-tightness during installation?
• The replacement interval for air filters should be determined by:
• How does a duct blower performance test relate to system efficiency?
• When performing a start-up, what is the first step?
• In a unit controlled by a thermostat the differential is the difference between __________.
• What is the color code for R-410A?
• The machine room ventilation example uses a multiplier with square footage to determine CFM. What is this multiplier?
• Using a psychrometric chart in the Modern Refrigeration, what will the wet bulb be if the dry bulb is 80 degrees and the humidity is 30%?
• The component connected to the end of a damper motor shaft and used to verify that the combustion blower is on is the
• A bathroom in a dwelling unit must be provided with a minimum intermittent exhaust of how many CFM?
• A one (1) ton refrigeration system has the equivalent of how many BTU's?
• What is the hazard of a negative draft condition in a gas-fired appliance?
• A device used to reduce noise caused by compressor pressure pulses is called a
• What is the primary purpose of an air filter in HVAC systems?
• What does 'two-stage cooling' mean?
• A (n) ___________ prevents slugging in a heat pump system.
• In thermostat-controlled equipment, the differential is defined as the difference between the temperature at which the switch turns the burners on and the temperature at which the switch turns the burners off.
• Chemicals are added to cooling tower water to address the following problems except-
• What is the typical process for determining electrical service size for an HVAC installation?
• Name three types of refrigerants commonly used in modern residential systems.
• CSST stands for?
• Which of the following is the minimum distance above the lowest interior portion of the flue for a connector?
• Rooms containing equipment requiring access shall be provided with an opening of not less than __________.
• The temperature for a fire damper actuating device shall not be less than how many degrees Fahrenheit?
• The minimum opening size for louvers used for exterior wall intake air openings is 1/4 inch. Which of the following is the correct minimum opening size?
• In a hydronic heating system, a three-way valve can direct hot water between which components?
• Which option is not a compliant condition for IMC metallic ducts installed in/under concrete?
• For combustion air openings used by fuel-burning appliances, the corrosion-resistant screen must have a minimum opening not less than what?
• Which device is used to measure electrical resistance?
• Prior to retrofitting refrigerant systems containing 250 pounds of refrigerant, what action must be taken?
• What is the primary difference between direct vent and power vent in gas appliances?
• If refrigerant is added to an air conditioner that has an external equalized TXV, the subcooling will
• What is the purpose of a manual gas shutoff valve installed near a furnace?
• The unit IWC stands for inches of water column and is used to measure pressure in HVAC duct systems.
• In Maryland code, what must be present on all refrigerant systems to be compliant with environmental regulations?
• The A/C thermostat shall be located where the average temperature is consistent. True or False?
• Duct insulation may cover a service opening when it is not identified.
• What is the purpose of a "pressure switch" in a furnace or air handler?
• The amount of makeup air is what in relation to the exhaust air in a kitchen exhaust system?
• How should refrigerant leaks be addressed to comply with EPA regulations?
• Hydronic pipe system should be cleaned with water and which chemical after installation?
• On a makeup water line that supplies a hydronic boiler, which two kinds of valves are required?
• What is ventilation air in a building?
• A circuit having a supply voltage of 240 volts and a resistance reading of 100 ohms will have an amperage reading of ____________.
• The term ‘low-heat appliance’ refers to a device whose flue gases enter the vent at approximately what temperature?
• What is the minimum intermittent mechanical ventilation rate of required outdoor air for a residential kitchen?
• A wall register on a floor furnace shall not be placed closer than how many inches to the corner?
• Horizontal pipes in a hydronic system should ________.
• Cooking appliances designed, tested, listed and labeled for use in commercial can be installed in domestic cooking.
• A controlled device responsive to relative humidity of the atmosphere is a ___________.
• Which instrument is specifically used to measure humidity by swinging a wet and dry bulb in air?
• A residential heating system has 16" galvanized duct. The minimum thickness required by code is __________.
• What is the purpose of a trap on a condensate drain?
• ARI 700 defines what aspect of reclaimed refrigerants?
• To ensure efficient heat distribution in a hot water system, the difference between boiler supply temperature and return temperature must not be less than how many degrees?
• A hot-water heating boiler with a 5,000,000 BTU/HR input shall have a minimum clearance from the top of the boiler to the ceiling of how many feet?
• Which unit measures electrical current?
• Convert 25°C to Fahrenheit.
• In a high-pressure boiler installation, where must shutoff valves be located?
• Outside air exhaust and intake openings shall be located a minimum of ______ feet from lot lines or buildings on the same lot.
• Central HVAC systems shall have air filters installed in which location?
• Which unit is used to express the crawl space ventilation rate mentioned in the material?
• What best describes a staged or modulating burner?
• What is the purpose of an economizer in eligible HVAC systems?
• Which instrument is listed as measuring electrical power?
• Materials used in plenums shall have a flame rating of ____________.
• In a typical split HVAC system, which component houses the evaporator coil?
• In a conditioned space, makeup air temperature must not differ from the room temperature by more than how many degrees Fahrenheit?
• Which device is commonly used to perform a duct leakage test under static pressure?
• What is the minimum opening size for louvers used for intake air openings in exterior walls?
• The test pressure shall be what value for the hot water heating system?
• A dwelling unit bathroom requires minimum intermittent exhaust of at least how many CFM?
• What is the minimum flame rating for plenums?
• If a plenum duct liner has a smoke index of 49, is it compliant with the stated maximum?
• In a zone control system, what role do dampers play?
• What is the function of a pressure relief valve on a boiler?
• If a condensate drain becomes clogged in a high-efficiency boiler, what is the most likely risk?
• How is a condenser sized for a central air system?
• Type of instrument used to measure electrical resistance?
• Ventilation requirement for a four-bedroom, three-bathroom, one-kitchen, and two-car garage home is how many CFM?
• The minimum temperature for a fire damper actuating device must be at least ______ degrees Fahrenheit.
• What is the primary purpose of EPA Section 608 certification in the HVAC trade?
• When capacitors are connected in parallel, the total capacitance is the sum of the individual capacitances.
• If you install a 20 mfd capacitor and a 40 mfd capacitor in parallel, you receive a total capacitance of _________.
• What is the primary function of a gas-fired appliance draft diverter or draft hood?
• Which gauge must be equipped on hot water heating boilers?
• Which valve on a makeup water line reduces pressure?
• Which value would violate the plenum duct liner smoke index limit (maximum 50)?
• What is the primary purpose of a condenser in a refrigeration system?
• What is the maximum operating pressure in an air duct system?
• When measuring voltage in a circuit, a voltmeter should be connected in which configuration?
• An auxiliary drain pan used in secondary drain systems for an A/C system shall have a minimum depth of ______ inch.
• Any appliance in which the products of combustion at the point of entrance to the flue under normal operating conditions have a temperature of 1000 degrees is a ____________ appliance.
• Return air openings for a forced-air heating system must be at least how many feet from the appliance to the ventilation outlet?
• Minimum size access opening for equipment installed in an underfloor area is ________?
• In a compressor, a run winding has what relative resistance compared to the start winding?
• With no air movement in a room ____________ can possibly occur?
• In Maryland, which codes are typically applied for gas piping leak-tightness testing?
• The unobstructed passageway around a boiler on all sides should be at least ______ inches.
• What is the maximum allowed temperature differential between makeup air and the conditioned space?
• Under what condition does an economizer typically bring in outdoor air for cooling?
• What is the main difference between a scroll compressor and a centrifugal compressor?
• What safety equipment should you wear when performing mechanical work with potentially energized circuits?
• What does the acronym HSPF stand for?
• In a hydronic system, horizontal pipes should be sloped toward the ______.
• What is the name of the tube or pipe used to carry refrigerant gas from the evaporator to the compressor?
• The internal diameter of 2 inch Type L copper pipe is approximately which value?
• ____________ temperature determines the defrost termination on a heat pump using time initiated temperature.
• In a chilled water system, a connection between different metallic piping materials must be made with ____________.
• For an uninhabited attic of 800 square feet exhausting by a mechanical system, what is the minimum outdoor air rate in CFM?
• Pipe insulation shall be used to protect refrigerant piping when surface temperature drops below ___________.
• Welding cylinders should be moved by which method?
• Which standards are typically used for load calculations in HVAC installations?
• For a 2000 sq ft Type II dry-cleaning system, the minimum exhaust flow is at least how many CFM?
• The burner on a gas hydronic heating system is controlled by _____________.
• When installed in a bedroom, a single wall-mounted unvented room heater is limited to an input rating not greater than __________.
• In a hydronic heating system, what does a 3-way valve do?
• Which code governs the hydronic piping?
• Which term describes the Heating Seasonal Performance Factor?
• What is a reason to perform a combustion analysis with a manometer or CO analyzer?
• What is the primary benefit of proper air balancing in terms of indoor comfort?
• What is the primary benefit of using direct-vent and sealed combustion appliances in terms of indoor air?
• What does Manual J, Manual D, and Manual S collectively help you determine?
• The purpose of a condensing boiler?
• The external equalizing line should be installed downstream of the thermostatic expansion valve at the ______.
• The unit used to express the ventilation rate in the provided examples is which of the following?
• True or False: A grease duct with an 80-foot length must be sloped at 1 inch per foot.
• For a two-car residential garage, what is the maximum ventilation rate allowed?
• How does a condensing boiler achieve higher efficiency than non-condensing models?