Maryland HVAC Masters Practice Test

These questions are part of the practice quiz. Start practicing

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