HVAC Math Practice Test

These questions are part of the practice quiz. Start practicing

• If a motor compressor has a 2" bore and a 3" stroke, what is the calculated piston displacement in cubic inches?
• What does the acronym "ASHRAE" stand for?
• What is the formula for calculating the area of a rectangle?
• Using a psychrometric chart, if the wet bulb temperature is 70 degrees F and the relative humidity is 50%, what is the dry bulb temperature of the air?
• What is the minimum ventilation rate for a public bathroom with one water closet and one lavatory with a floor area of 35 square feet?
• How do you calculate the heat gain through insulation?
• Which metric is crucial for maintaining healthy indoor air quality?
• In duct airflow calculations, why is the duct area important?
• What is the latent heat load in BTUh for air at 1500 CFM with an absolute humidity difference of 28 grains?
• How do you calculate the tons of air conditioning needed for a room?
• What is the required volume of indoor combustion air for an 80% AFUE 100,000 Btu/hr gas furnace?
• What does the term "BTU" stand for?
• What heat is needed to change 10 pounds of ice at 32°F into water at 80°F?
• Given a winter design temperature of 25°F and an indoor temperature of 75°F, what is the heat loss due to infiltration at 25 cfm?
• What is the formula for calculating the minimum area of combustion air openings based on input Btu/h?
• How do you determine the adequate airflow for ventilating a space?
• How do you do a pressure conversion from pascals to psi?
• What is the maximum vertical spacing for installing steel piping in a hydronic system?
• How do you calculate the dew point temperature?
• How is pressure drop calculated in a piping system?
• How do you calculate the size of a heat pump system?
• How do you convert cubic feet to gallons?
• What is the formula for calculating the latent heat of vaporization?
• How much heat in BTUs is required to melt a 20-pound block of ice from 4°F to 45°F?
• Which factor is crucial for a heat exchanger's performance?
• Using the psychrometric chart, what would be the approximate dry bulb temperature in degrees F with a humidity ratio of 79 grains per # dry air and a wet bulb temperature of 68 degrees F?
• For a duct measuring 10 inches by 20 inches, what is the area in square feet?
• For an 80,000 Btu/h Category 1 gas furnace, how much CFM of combustion air is required?
• What is the theoretical efficiency formula used to calculate volumetric efficiency?
• For a 15,000 square foot auditorium, what is the minimum outdoor ventilation requirement in CFM?
• What is the capacity of a 1 1/4 inch schedule 40 natural gas line with a length of 60 feet at 2 psi?
• For a Category I natural draft gas appliance with an input rating of 125,000 Btu/h, what is the appropriate size vent required for a height of 15 feet and a 2-foot lateral?
• Calculate the total cubic feet of a room that is 10 ft long, 8 ft wide, and 9 ft high.
• How do you calculate the length of ductwork needed for a system?
• How many ounces are in a gallon?
• What is the U value of a wall section with R values of 19, 0.015, and 0.02?
• When using the IFGC guidelines, what is the standard calculation for combustion air openings for gas appliances?
• What is the maximum winter humidity design for an inside temperature of 72°F when the outside temperature is 10°F?
• How do you determine the thermal resistance (R-value) of materials?
• How much energy (BTUs) is released when 1 pound of steam condenses?
• Which component is primarily responsible for heat loss in ducts?
• What is the approximate room volume if a room measures 12 ft by 10 ft and is 8 ft high?
• How do you convert watt-hours to kilowatt-hours?
• What is the RPM required for a fan to increase airflow from 800 CFM to 1,000 CFM if the original speed is 300 RPM?
• For a fuel-burning appliance installed in a confined space, what is the minimum area for each combustion-air opening for a 300,000 Btu/h appliance?
• What is the purpose of the SHGC in thermal load calculations?
• What is the formula for finding the volume of a cylinder?
• What is the formula used to calculate the surface area of a sphere?
• If the capacity of an 80-foot, 23 EHD CSST is required given certain pressures and specific gravity, what is the capacity in cfh?
• How many BTUs are needed to cool a 1,200 sq ft room?
• What formula is used to determine the efficiency of a heating system?
• How do you convert Fahrenheit to Celsius?
• What is the average temperature difference used in heat loss calculations when indoor temp is 75°F and outdoor temp is 25°F?
• If a system is using a 12" round flexible duct with an air velocity of 600 CFM, what is the air velocity measurement expressed in feet per minute?
• How do you convert cubic feet per minute (CFM) to liters per second (L/s)?
• Which of the following contributes to high humidity levels indoors?
• According to IMC guidelines, what is the minimum tubing size required for a system with a capacity of 65 tons of refrigerant?
• How do you calculate the temperature rise in an HVAC system?
• What happens to superheat in a saturated refrigerant system?
• What is the maximum screen opening size approved for fresh air ventilation caps in commercial applications?
• What is the dry bulb temperature when the wet bulb temperature is 67 degrees F and the humidity ratio is 80 grains/# dry air?
• What does the term "enthalpy" refer to in HVAC physics?
• What commonly affects the efficiency of a cooling system?
• What is the primary purpose of manifolded drain pipes in condensate drainage systems?
• What is the pressure drop in psi for the capacity calculation of the gas line in the last question?
• For a flexible duct with 10 inch diameter and 10% compression, what would be the effective length of the duct?
• Using a 14 by 14 inch rectangular duct, what would be the result if the velocity is increased to 1200 FPM?
• If the dry bulb is 80 degrees and the humidity is 30%, what will the wet bulb be according to the psychrometric chart?
• If a pipe has a diameter of 4 inches, what is its radius in inches?
• When calculating CFM in a duct, what unit is air velocity measured in?
• What is the relationship between pressure, volume, and temperature in a gas described by Boyle's Law?
• What is the relationship between duct size and airflow efficiency?
• How do you calculate the total heat gain in a space?
• What is the normal ventilation requirement for a machinery room of 400 square feet occupied by 3 persons?
• What equation represents the first law of thermodynamics in HVAC systems?
• What does SEER stand for?
• For a system with 120 CFM air quantity, what is the approximate friction loss in inches of water per 100 feet of duct?
• How is seasonal energy efficiency ratio (SEER) calculated?
• What is the formula for calculating the refrigerant flow rate?
• What is the formula for calculating pressure drop in a duct?
• How do you calculate the refrigerant charge in a system?
• How many BTUs are lost per hour if a 1,000 sq ft roof has an R-value of 19 and the temperature difference is 20°F?
• What does EER stand for in HVAC terminology?
• What unit is used to express BTUs in HVAC systems?
• What is the least cfm allowed for an intermittent exhaust in a residential bathroom?
• In calculating CFM from air velocity and area, which formula is used?
• How many BTUs of cooling does a medium-sized room with an area of 200 square feet approximately need?
• What are common units for measuring airflow in HVAC systems?
• In the purging process, what is the length of 6-inch gas piping that requires purging?
• Which factor is critical in determining the efficiency of a heat pump?
• What is the required duct size for a duct system delivering 1,000 cfm with a pressure drop of 0.25 IWC and a friction rate of 0.095 IWC/100?
• In HVAC calculations, what unit represents the efficiency and speed of air movement through a system?
• What is the formula to find the capacity of a heat pump?
• What formula is used to calculate the cooling load required for a space?
• What is the approximate density of water in pounds per gallon?
• How is the total heat load affected by external gains in a commercial building?
• What is the purpose of using a pressure gauge in HVAC systems?
• What does ΔT represent in the thermal load formula?
• How do you convert Fahrenheit to Celsius?
• How do you convert psi to inches of mercury (inHg)?
• What is the specific heat of air in BTUs per pound per degree Fahrenheit?
• How do you calculate thermal load for a window?
• How is total heat load calculated for a commercial building?
• How is the sensible heat ratio calculated?
• What is the formula to calculate duct size in HVAC systems?
• How do you calculate the efficiency of an air conditioning unit?
• How do you calculate the temperature drop in an HVAC system?
• What is the basic principle of a heat exchanger?
• To calculate the U value from R value, you must:
• What is the primary purpose of an HVAC system?
• What role does the friction factor play in pressure calculations?
• What unit is commonly used to express air flow rate in HVAC systems?
• How do you determine the airflow in a ductwork system?
• If the air velocity in a duct is 500 fpm and the duct dimensions are 10" x 20", what is the calculated CFM?
• What is the formula for calculating the amount of energy consumed?
• How is the heating season defined in HVAC?
• In duct calculations, what is the first step when measuring cross-sectional area?
• Which of the following factors is essential for duct size calculations?
• What is the formula used to calculate the new RPM for a fan?
• What is the total airflow in CFM if the air velocity is 500 fpm and the duct area is 1.38 square feet?
• What is the formula to calculate the weight of a cubic foot of air at sea level?
• In a duct system, how do you calculate the friction loss per 100 feet?
• For a 3/4 inch horizontal copper pipe, what is the maximum support spacing recommended?
• What is the relationship of cooling load factor in HVAC calculations?
• What is the minimum gauge thickness for an 8-inch round aluminum duct in a residential building?
• What unit would you primarily use to measure cooling capacity in HVAC systems?
• Which method is commonly used to determine the gauge thickness for round ductwork?
• What is the formula for the efficiency of a heating system?
• In the HVAC industry, what is the significance of maximum support distance for tubing?
• What is the formula for calculating duct size based on airflow?
• What is the density of standard air if the specific volume is 13.33 cubic feet per pound?
• How do you calculate the humidity ratio in HVAC systems?
• What does the acronym "HVAC" stand for?
• What is the formula for determining energy loss in ducts?
• What is the smallest CSST gas tubing size (EHD) that can be used for a 90-foot piping system with a total pressure drop of 6-inch water column?
• Which formula correctly calculates the efficiency of a cooling tower?
• How does increasing the CFM affect the static pressure in an HVAC system?
• How do you calculate the heat load for a residential space?
• How do you calculate the total static pressure in a duct system?
• What formula do you use to calculate the airflow required to cool a space?
• What is the temperature conversion from Celsius to Kelvin?
• What is the importance of specifying proper duct sizing in HVAC systems?
• Which units are commonly used to measure airflow in HVAC systems?
• Which of the following tools is primarily used for measuring temperature in HVAC applications?
• What is the diameter of duct required if the airflow is 500 CFM at a velocity of 600 FPM?
• What is the formula to calculate the pressure required to create a specific flow rate?
• Which of the following is necessary when sizing a vent for a gas appliance according to IFGC standards?
• In terms of BTUs, how much energy is involved in changing the state of ice to water at 32°F?
• Using a 10 inch flexible duct with 15% compression and 700 FPM velocity, what is the approximate CFM air quantity?
• Calculate the volume of a triangular prism with a base area of 20 square feet and height of 10 feet.
• What is the angle conversion from degrees to radians for a 90° angle?
• What is the minimum area required for outdoor openings for a gas appliance with a 60,000 Btu/h input rating when drawing air through two horizontal ducts?
• Why is careful ventilation measurement important in HVAC systems?
• How do you calculate the total resistance in a series circuit?
• How is the fluid density relevant in calculating pressure for fluid flow?
• What is the minimum CFMs required per station for ventilation tables in nail salons?
• A 100,000 Btu/h gas furnace requires how many cubic feet of combustion air?
• For an effective HVAC system, which factor is crucial in fan and duct design?
• What is superheat in an HVAC context?
• How do you find the specific heat of a substance?
• What is the minimum total free area required for a 120,000 Btu furnace supplied with combustion air from inside a building?
• Which method is used to find the required volume of indoor combustion air?
• How do you calculate pressure loss in a duct system?
• What is the approximate air quantity in CFM through a 14 by 14 inch rectangular duct at 1000 FPM velocity?
• What is the appropriate sheet steel thickness for a high heat metal chimney with an 18-inch diameter?
• How do you calculate the flow rate of water in a heating system?
• What is the formula for calculating BTUs for heating or cooling a space?
• When adjusting fan performance, how is CFM related to RPM?
• For a 150,000 Btu/h category 1 forced draft appliance, what is the minimum pipe diameter required to use a "Type B" double wall pipe?
• What is the coefficient of performance (COP) in HVAC?
• How do you calculate the flow rate of air in CFM (Cubic Feet per Minute)?
• What is the primary purpose of airflow measurement in HVAC systems?
• How many BTUs are there in one kilowatt-hour (kWh)?
• What formula do you use to calculate the height of a chimney?
• What is the required steel duct diameter for a system set at 700 feet per minute velocity with a design friction loss of 0.08 inches water column and 380 CFM airflow?
• What is the maximum distance allowed between horizontal supports for 2-inch nominal size steel gas pipe?
• What does the acronym BTU stand for in HVAC terminology?
• What is the recommended action regarding the venting of a fan assisted Category 1 appliance with an input rating of 55,000 Btu/h into a 20-foot high chimney?
• How many feet are in a mile?
• What is the minimum size of the combustion air ducts required for a 125,000 Btu/h fan-assisted appliance and a 65,000 Btu/h heater?
• Using the formula for CFM, if a duct measures 40 inches by 22 inches and the air velocity is 1,500 fpm, what is the CFM?
• If an HVAC system's combustion air is calculated using a non-vented system, which method is acceptable?
• What is the formula to calculate the pressure-volume work done by a gas?
• What does the term "latent heat" refer to in HVAC?
• What is the result of adjusting the static pressure drop of a filter, evaporator coil, and system registers, given specific pressure losses?
• How do you find the density of air at a given temperature?
• How do you convert kilowatts to horsepower?
• How is the energy efficiency ratio (EER) calculated?
• What would be the capacity in cubic feet of gas per hour for a gas pipe installation using Schedule 40 metallic pipe with a pressure drop of 0.5 in. W.C.?
• What is the CFM delivered by a duct with an air velocity of 2,000 fpm and a cross-sectional area of 12” x 12”?
• What is the formula to calculate the area of a rectangle?
• A compressor with a displacement of 10 cubic inches pumps how much volume if its volumetric efficiency is 60%?
• Given a pressure difference of 1 inch water column, what is its equivalent in PSI?
• How do you determine the estimated load for cooling in HVAC?
• What is the ideal refrigerant pressure for residential systems?
• In the context of HVAC, what does CFM stand for?
• In HVAC systems, what does the acronym CFM stand for?
• What does the acronym CFM stand for in HVAC calculations?
• What unit measures thermal resistance?
• How do you calculate the condensate produced by a cooling system?
• What is the volume of a cube with each side measuring 3 feet?
• At what liquid pressure would R-410A be found at a saturation temperature of 40 degrees F?
• If a compound gauge reads 248 psig and the actual line temperature is 100°F, what is the subcooling using R-22 refrigerant?
• What is the primary purpose of a hydronic heating system?
• What is the resistance of a material with a conductivity of 0.37 Btu/(hour square foot degree F)?
• How do you calculate the heat load in BTUs for a space?
• What is the approximate weight of 10 gallons of water?
• Which of the following affects the efficiency of a cooling tower?
• How is the efficiency of cooling systems typically measured?
• How is the thermal conductivity (k) measured?
• What temperature difference is used in calculating CFM from sensible load and supply air temperature?
• What is the formula for calculating the power of a heat pump?
• What is the maximum distance allowed between supports for horizontal 1/2 inch O.D. tubing?
• What unit is used to measure energy?
• What is the formula for the area of a circle?
• How much energy does a 1,500W heater consume in 3 hours?
• What is the significance of the coefficient of performance (COP) in HVAC?
• What is the friction loss in inches of water per 100 feet of duct for a 12 inch flexible duct with 4% compression and 1500 CFM air quantity?
• What is the maximum horizontal spacing for a 3/4 inch diameter copper tubing as per Piping Support Spacing regulations?
• What is the standard atmospheric pressure at sea level in PSI?
• How do you calculate the area of a triangle?
• For a combustion air opening requirement, how much square inch area is needed for a total input of 190,000 Btu/h?
• What formula do you use to determine the airflow in an HVAC system?
• What is the specific heat formula?
• Which variable is NOT part of the equation for humidity ratio?
• What is the significance of the temperature difference in BTU calculations?
• How is sensible heat gain determined in a heat loss calculation?
• Which of the following items contributes to calculating the required duct size in an HVAC system?
• When calculating CFM for a space with a sensible load of 50,250 BTUs and supply air temperature of 58 degrees F, what is the CFM delivered?
• What is the maximum allowable height of a notch located 5 feet from the end of a 2" x 12" joist that is 12 feet long?
• What formula do you use to determine duct airflow velocity?
• What is the formula for calculating the volume of a cylinder?
• What is the formula for calculating the total BTU output of a heating unit?
• What is considered a reasonable range of Btu's to cool a 200 square foot room based on general standards?
• What is the smallest size of iron pipe required for a system with 165 cubic feet/hr of gas at 1 psi?
• Convert 50 PSI to inches of mercury.
• What is the most length of pipe needed for a natural gas system using a 1/2-inch schedule 40 iron pipe carrying 120 cubic feet per hour?
• What is the Reynolds number used for in HVAC systems?
• What code specifies that no notch may be located where the joist section exceeds 4 feet in the middle?
• What protection is recommended for gas-fired equipment requiring an 18-inch clearance wall?
• What is the Pythagorean theorem?
• What is the duct design friction loss when the available external static pressure is 0.80 inches of water column, with static pressure drops totaling 0.65 inches?
• What is the pressure drop for the duct system delivering 1,000 cfm as referenced in the calculations?
• What do you use to measure airflow in HVAC systems?
• How many threads approximately will be cut on a 3-inch steel gas line?
• What effect does high humidity have on the human body?
• How many square feet are there in one acre?
• Why must the air supplied for combustion be adequate in volume?
• What is the formula to calculate the circumference of a circle?
• What is the formula for calculating the area of a circle?
• What mathematical operation is used to adjust fan RPM based on airflow changes?