EGEE 102 Exam 3
Oil is sold in a particular region at $1.10/gal and natural gas at $11.47 per MCF. Given that the oil has a heating value of 140,000 Btus/gal and natural gas of 1 MMBtu/MCF, which fuel is cheaper to use? A ) Oil B ) Natural Gas
(1.10/gal) / (140,000 BTU/gal) = (1.10 / 140,000) BTU (1.10 / 140,000) BTU x (1 MMBTU / 1,000,000 BTU) = $7.86/MMBTU Natural Gas: ($11.47/MCF) x (1 MMBTU/1 MCF) = $11.47/MMBTU
The average cost of electricity in the US is ______. A ) $80/MWh B ) $8.0/kWh C ) $0.08/MWh D ) $0.80/kWh
A ) $80/MWh Typical Electricity price is $0.08/KWH = $80.00/MWH
A heat pump (heating) with a COP of 3.3 maintains an indoor temperature of 65 degrees F. What is the outside temperature (in oF)? A ) -94 F B ) -45 F C ) 94 F D ) 45 F
A ) -94 F 65 oF = (65 - 32) 5 / 9 oC = 18.33oC = 18.33 + 273 K= 291.33 K ' 3.3 = 291.33 / (291.33 - tcold) ' tcold = 291.33 - 291.33 / 3.3 = 203.04 K = 203.04 - 273 oC = -69.96 oC = (-69.96 x 9 / 5) + 32 oF = -93.93 oF
The heat loss through a window (R-2) is 10 MMBTU/year. Calculate the payback period (in years) if Krypton is filled in the window to increase the effective R-value of the window to 13. Assume heating price to be $10/MMBTU and the cost for filling Krypton is $45. A ) 0.53 B ) 84.7
A ) 0.53 Heat lost through new window per year = (10 x 2) / 13 = 1.53 MMBTUs/yr Reduction in heat lost per year = 10 - 1.53 = 8.47 MMBTUs/yr Savings in energy cost per year = 8.47 x 10 = $84.7 Payback period = 45 / 84.7 = 0.53 yrs
Mr. and Mrs. Martin's home is heated by a natural gas furnace and has an Annual Heat Loss of 79,081,683.91 BTUS. Natural gas in their area costs $1.269/CCF and has a Heating Value of 100,000 BTUs/CCF. The Martins recently purchased a furnace for their home that will result in an Annual Heating Cost of $1080. What is the efficiency of the Martin's new furnace? A ) 0.929 B ) 1.076 C ) 0.83 D ) 0.97
A ) 0.929 Amount of Natural gas that was burnt in new furnace = 1080/1.269 = 851.0638298 CCF = 851.0638298 x 100,000 BTU = 85,106,382.98 BTU ' Efficiency = 79,081,683.91 / 85,106,382.98 x 100 = 92.92%
What is the coefficient of performance for a heat pump that maintains an indoor temperature of 75ºF when it is 25ºF outside? A ) 10.7 B ) 1.5 C ) 7 D ) 5.5
A ) 10.7 COP = Thot/(Thot-Tcold) Tcold = 25 F = (25-32)x5/9 C = -3.89 C = -3.89 + 273 K = 269.11 K Thot = 75 F = (75-32)x5/9 C = 23.89 C = 23.89 + 273 K = 296.89 K COP = 296.89/(296.89-269.11) = 10.69
In State College, PA the average outside temperature during the month of January was 28 oF. Calculate the HDD for the month of January. A ) 1147 B ) 37
A ) 1147 HDD = (65-28) x 31 = 1147 degree-days
A wall consists of 0.5" wood siding (R = 0.81), 0.75" plywood (R = 0.94), 3.1" of fiberglass (R = 3.7 per inch) and 0.5" plasterboard (R = 0.45). What is the composite R-value of the wall? A ) 13.67 B ) 5.9
A ) 13.67 Composite R-value = 0.81 + 0.94 + (3.1 x 3.7) + 0.45 = 13.67
A room has a wall with an R value of 18 F sq.ft. hr/BTU. The room is 15 feet long and 11 feet wide with walls that are 9 ft high. On a particular day the average outside temperature is 40 degrees F. How much heat is transferred through the walls on that day (in BTUs)? A ) 15600 B ) 650
A ) 15600 Total area of walls = 2 ((15 x 9) + (11 x 9)) = 468 sq.ft HDD = 65-40 = 25 oF Heat transferred = 468 x 25 x 24 / 18 = 15600 BTUs
Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1004 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $757. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $10.3/MCF. Assuming an AFUE of 87.5%, how long will it take Dave to recover his investment (in years)? A ) 16.6 B ) 398.4
A ) 16.6 Cost of insulation = 757 / 1004 = 0.7539 $/sq.ft Cost of energy = 10.3 / 1,000,000 = 0.0000103 $/BTU Time to recover investment = (0.7539 x 16 x 28 x 0.875) / (0.0000103 x (28 - 16) x 6000 x 24) = 16.6 yrs
A wall is made up of 7 inches of stone (R=0.08/inch), 4 inches of polyurethane board (R value=5.25/inch), and 0.75 inches of plywood (R value= 0.94). Calculate the composite R-value for the wall. A ) 22.5 F sq.ft. h/BTU B ) 11.94 F sq.ft h/BTU C ) 22.26 F sq.ft h/BTU D ) 6.27 F sq.ft h/BTU
A ) 22.5 F sq.ft. h/BTU Composite R-value = 7x0.08 + 4*5.25 + 0.94 = 22.5
117 CCF of natural gas is equivalent to how many kWh of Electricity? A ) 3429.07 B ) 11699997
A ) 3429.07 We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU 117 CCF = 117 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 3429.073 KWH
135 CCF of natural gas is equivalent to how many kWh of Electricity? A ) 3956.62 KWH B ) 39.57 KWH C ) 395.66 KWH D ) 39566.24 KWH
A ) 3956.62 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 135 CCF = 135 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 3956.623 KWH
The coefficient of performance for a single heat pump in heating mode is greatest at which temperature? A ) 50 F B ) 25 F C ) 10 F D ) it depends on the heat pump
A ) 50 F The coefficient of performance for a single heat pump in heating mode is greatest at 50F
Which one of the following provides the most insulation? A ) 6 inches of Cellulose B ) 6 inches of Fiberglass C ) 6 inches of Common brick
A ) 6 inches of Cellulose
Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1821 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $810. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $14.5/MCF. Assuming an AFUE of 80.9%, how long will it take Dave to recover his investment (in years)? A ) 6.4 Years B ) 0.6 Years C ) 11716.6 Years D ) 643.4 Years
A ) 6.4 Years Cost of insulation = 810 / 1821 = 0.4448 $/sq.ft Cost of energy = 14.5 / 1,000,000 = 0.0000145 $/BTU Time to recover investment = (0.4448 x 16 x 28 x 0.809) / (0.0000145 x (28 - 16) x 6000 x 24) = 6.43 yrs
Katy is planning on adding additional insulation to her roof, which costs $2882. It is estimated that she can save $397/year on energy costs from this modification. What is the pay back period (in years)? A ) 7.3 B ) 8
A ) 7.3 Pay back period = 2882/397 = 7.25 yrs
In State College, PA the average outside temperature during the month of January was 40 degrees F. Calculate the HDD for the month of January. A ) 775 degree days B ) 25 degree days C ) 1240 degree days D ) 750 degree days
A ) 775 degree days HDD = (65-40)*31 = 25*31 = 775 degree-days
Which one of the following devices can be used to both heat and cool a house? A ) A Heat Pump B ) A Furnace C ) A Radiator D ) A Solar Panel
A ) A Heat Pump Heat pumps can be used to both heat and cool a house.
Compared to a house built in the 1960's, a house built today has ______. A ) A greater R-value B ) A lesser R-value C ) No R-value D ) About the same R-value
A ) A greater R-value Newly build houses are built with better insulation. Thus, they have greater R-value.
What kind of efficiency rating do gas and oil heating systems use? A ) AFUE B ) EER C ) EF D ) COP
A ) AFUE AFUE is used to rate efficiency of gas and oil heating systems
Which of the following is recommended to look at when purchasing a furnace A ) Annual Fuel Utilization Efficiency B ) Combustion Efficiency
A ) Annual Fuel Utilization Efficiency Annual Fuel Utilization Efficiency
To calculate the heating degree days for a particular day, the day's outside temperature is calculated by _____. A ) By adding the high and low temperatures and then dividing by two. B ) By subtracting the low from the high temperatures and then dividing by two. C ) Subtracting the outside temperature from the inside temperature D ) Subtracting the inside temperature from the outside temperature
A ) By adding the high and low temperatures and then dividing by two. To calculate the heating degree days for a particular day, find the day's average outside temperature (by adding the high and low temperatures), then dividing by two.
What is the name given to the weatherization process used in sealing cracks in windows, doors and walls? A ) Caulking B ) Insulating C ) Painting
A ) Caulking Caulking is used in weatherization process used in sealing cracks in windows, doors and walls
When you place a spoon into a cup of cocoa it gets hot over time. What is this due to? A ) Conduction B ) Convection C ) Radiation
A ) Conduction Conduction is a process by which energy is conducted down the rod as the vibrations of one molecule are passed to the next.
Heat is lost through walls, windows and roof of a house. What is the primary mechanism of such heat loss? A ) Conduction B ) Convection C ) Radiation
A ) Conduction Heat loss through solid materials occurs by conduction.
Warm water rises in a lake and cold water descends. What is this due to? A ) Convection B ) Conduction C ) Radiation
A ) Convection Convection is a process by which energy is transferred by the bulk motion of the fluids (gases or liquids).
Which of the following items is used in a passive solar heating system? A ) Deciduous Trees B ) Photovoltaic Cells C ) Flat Plate Collectors D ) A Geothermal Heat Pump
A ) Deciduous Trees No auxilliary devices that use external energy are used in a passive solar heating system
A house that effectively uses passive solar heating and cooling will_____. A ) Face south and have deciduous trees growing on the south side to block heat in the summer and allow sunlight in the winter. B ) Have large windows on the east and west sides of the house to maximize solar intake throughout the whole day. C ) Have solar panels on the roof and around the house. D ) Face east and have deciduous trees growing on the south side to block heat in the summer and allow sunlight in the winter.
A ) Face south and have deciduous trees growing on the south side to block heat in the summer and allow sunlight in the winter. A house that effectively uses passive solar heating and cooling will face south and have deciduous trees growing on the south side to block heat in the summer and allow sunlight in the winter
Which of the following air systems is the most commonly used type of central heating and cooling system? A ) Forced Air Duct B ) Radiant baseboard C ) Hydronic D ) Electric Resistance
A ) Forced Air Duct Forced Air Ductis the most commonly used type of central heating and cooling system
The number of degrees the mean temperature falls below 65 degrees F for a given day is indicated by _____ . A ) HDD B ) CDD C ) Heat index D ) AFUE
A ) HDD The HDD indicates how many degrees the mean temperature fell below 65ºF for the day.
The time it takes to recover the additional cost through savings is called _____. A ) Pay Back Period B ) Return of investment C ) Overhead return
A ) Pay Back Period Payback period is the amount of time it takes to recover the additional cost through savings
Which one of the following items is used in a passive solar heating system? A ) South facing windows B ) Photo-voltaic Cells C ) Flat Plate Collectors D ) A Geothermal Heat Pump
A ) South facing windows South facing windows are used in a passive solar heating system
What is nearly half of the energy used at home used for? A ) Space heating and cooling B ) airconditiong C ) stoves D ) refrigerators
A ) Space heating and cooling Nearly 44% of the energy at home is used for home heating and cooling
Which one of the following is an example of thermal mass? A ) Stone B ) Straw C ) Styrofoam D ) Wood
A ) Stone Stone, water, or concrete can be considered thermal masses.
All air-source heat pumps are rated by "heating season performance factor" (HSPF) A ) TRUE B ) FALSE
A ) TRUE All air-source heat pumps are rated by "heating season performance factor" (HSPF)
The furnace/air conditioner will run for longer periods of time when the air filter is dirty.
A ) TRUE Dirty air filters reduces amount of air that is circulated making the furnace/air conditioner work for longer periods of time
HDD is used to estimate the amount of energy required for residential space heating during heating season. A ) TRUE B ) FALSE
A ) TRUE HDD is used to estimate the amount of energy required for residential space heating during a heating season.
Using kitchen and bath exhaust fans may adversely affect the heating and cooling requirements A ) TRUE B ) FALSE
A ) TRUE Kitchen and bath exhaust fans constantly pumps air from inside the house to the surroundings. This means the duty of heater and air conditioner increases.
Most of the synthetic insulation products are very effective insulation materials. A ) TRUE B ) FALSE
A ) TRUE Most of the synthetic insulation products such as polystyrene or polyurethane are very effective insulation materials
On a summer afternoon you should keep the draperies closed on all west-facing windows to block out the hot sun A ) TRUE B ) FALSE
A ) TRUE On a summer afternoon you should keep the draperies closed on all west-facing windows to block out the hot sun
The higher the R-value, the greater the insulating effectiveness. A ) TRUE B ) FALSE
A ) TRUE R-value is a measure of insulating effectiveness of a material. The higher the R-value, the greater the insulating efectiveness
When you insulate the attic of a home the R-value of insulation increases at the same rate as its thickness. A ) TRUE B ) FALSE
A ) TRUE R-value is a measure of the effectiveness of an insulation. Its R-value is increases at the same rate as its thickness
When you insulate the attic of a home the R-value of insulation increases at the same rate as its thickness. A ) TRUE B ) FALSE
A ) TRUE R-value of insulation increases at the same rate as its thickness. Refer to screen 4 in 'Lesson 7b - Insulation and Home Heating Fuels'
The home heating and cooling system is the major residential user of energy A ) TRUE B ) FALSE
A ) TRUE The home heating and cooling system is the major residential user of energy
Thermal-lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning. A ) TRUE B ) FALSE
A ) TRUE Thermal lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning
Thermal-lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning. A ) TRUE B ) FALSE
A ) TRUE Thermal-lined draperies and outdoor awnings can significantly reduce the energy required for air conditioning
When using a fire place, most of the heated air is lost through the chimney. A ) TRUE B ) FALSE
A ) TRUE True, about 75% of the heated air is lost through the chimney.
Using kitchen and bath exhaust fans may adversely affect the heating and cooling requirements. A ) TRUE B ) FALSE
A ) TRUE Use of kitchen and bath exhaust fans lead to venting out already heated or cooled from inside the house. This increases heating and cooling requirements.
Which one of the following is not an advantage of forced air heating systems? A ) They usually have a very high efficiency (80-90%) B ) Ducts can easily be used for A/C in the summer C ) Rooms are heated quickly D ) The system isn't very complicated
A ) They usually have a very high efficiency (80-90%) The efficiency is around 50%.
The R-value of a composite wall is calculated by _____. A ) adding the R-values of all layers B ) averaging the R-values of all layers
A ) adding the R-values of all layers The R-value of a composite wall is calculated by adding the effective R-values of each of the layers of the wall
In heating mode when the refrigerant liquid moves past the expansion valve it_____. A ) evaporates, absorbing heat from the outside B ) evaporates, giving off heat to the outside C ) condenses, absorbing heat from the outside D ) condenses, giving off heat to the outside
A ) evaporates, absorbing heat from the outside In heating mode when the refrigerant liquid moves past the expansion valve it evaporates, absorbing heat from the outside
The compressor of a heat pump system ___________ the pressure of the refrigerant, ________ its temperature. A ) increases, raising B ) decreases, lowering C ) increases, lowering D ) decreases, raising
A ) increases, raising The compressor increases the refrigerants pressure, increasing its temperature
When a heat pump is used to heat a house in the winter, how will the coefficient of performance be affected if the inside set temperature is changed from 65 F to 70 F? A ) it decreases B ) it increases C ) it may become negative D ) it stays the same
A ) it decreases
When looking at a graph of BTUs/h and outdoor temperature, the amount of supplemental heat (in BTUs) can be determined by_____. A ) subtracting home heating requirement BTU point for a specific temperature by the heat pump output BTU point for the same temperature, to the left of the balance point B ) subtracting home heating requirement BTU point for a specific temperature by the heat pump output BTU point for the same temperature, to the right of the balance point C ) multiplying the given temperature by the home heating requirement in BTUs. D ) Adding the balance point BTUs to the minimum heat pump output BTUs.
A ) subtracting home heating requirement BTU point for a specific temperature by the heat pump output BTU point for the same temperature, to the left of the balance point subtractingto the left of the balance point, because we want to find the BTU difference between heat pump output and home heating requirements, where the requirements are greater than the output.
Radiant floor systems heat _____. A ) the entire floor B ) localized spots C ) Some corners of the room
A ) the entire floor Radiant floor systems heat the entire floor
What happens when the outside temperature falls below the 'Balance Point'? A ) the heat pump output falls below the home heating requirement B ) the home heating requirement equals the heat pump output C ) the home heating requirement falls below the heat pump output
A ) the heat pump output falls below the home heating requirement when the outside temperature falls below the 'Balance Point' the heat pump output falls below the home heating requirement
The collector's efficiency increases as ______. A ) useful energy delivered increases (insolation remains constant) B ) the sun sets C ) insolation increases (useful energy delivered remains constant) D ) the sun rises
A ) useful energy delivered increases (insolation remains constant) Collector's Efficiency = Useful energy deliverd/insolation on collector*100, and therefore if the useful energy delivered increases, the collector's efficiency will increase.
A heat mover _____. A ) uses work to move heat from a low temperature reservoir to a high temperature reservoir B ) uses heat moving from a high temperature reservoir to a low temperature reservoir to produce work C ) uses work to move heat from a high temperature reservoir to a low temperature reservoir D ) uses heat moving from a low temperature reservoir to a high temperature reservoir to produce work
A ) uses work to move heat from a low temperature reservoir to a high temperature reservoir A heat mover uses work to move heat from a low temperature reservoir to a high temperature reservoir
A heat pump (heating) with a COP of 3.8 maintains an indoor temperature of 64 degrees F. What is the outside temperature (in oF)? A ) -47 F B ) -74 F C ) 47 F D ) 74 F
B ) -74 F 64 oF = (64 - 32) 5 / 9 oC = 17.77oC = 17.77 + 273 K= 290.77 K ' 3.8 = 290.77 / (290.77 - tcold) ' tcold = 290.77 - 290.77 / 3.8 = 214.25 K = 214.25 - 273 oC = -58.75 oC = (-58.75 x 9 / 5) + 32 oF = -73.75 oF
The heat loss through a window (R-1) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 7. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20. A ) 0.2 years B ) 0.23 years C ) 1.4 years D ) -0.03 years
B ) 0.23 years Heat lost through new window per year = (10 x 1) / 7 = 1.42 MMBTUs/yr Reduction in heat lost per year = 10 - 1.42 = 8.58 MMBTUs/yr Savings in energy cost per year = 8.58 x 10 = $85.8 Payback period = 20 / 85.8 = 0.23 yrs
A freezer maintains a temperature of 30ºF while the outside temperature is 75ºF. What is the COP of the freezer cooling system? A ) 1.67 B ) 11.8 C ) 15.6 D ) 11.5
B ) 11.8 COP = Thot/(Thot-Tcold) Tcold = 30 F = (30-32)x5/9 C = -1.11 C = -1.11 + 273 K = 271.89 K Thot = 75 F = (75-32)x5/9 C = 23.89 C = 23.89 + 273 K = 296.89 K COP = 296.89/(296.89-271.89) = 11.87
A room has a wall with an R value of 16 F sq.ft. hr/BTU. The room is 16 feet long and 8 feet wide, with walls that are 9 ft high. On a particular day the average outside temperature is 34 degrees F. How much heat is transferred through the walls on that day (in BTUs)? A ) 837 BTUs B ) 20088 BTUs C ) 53568 BTUs D ) 1116 BTUs
B ) 20088 BTUs Total area of walls = 2 ((16 x 9) + (8 x 9)) = 432 sq.ft HDD = 65-34 = 31 oF Heat transferred = 432 x 31 x 24 / 16 = 20088 BTUs
A house in State College, PA (HDD=6000) has 323 ft2 of windows with R value = 2.5, 1970 ft2 of walls with R value = 18, and 1266 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)? A ) 6812.61 BTUs B ) 40875657.14 BTUs C ) 14919614.86 BTUs D ) 1703152.38 BTUs
B ) 40875657.14 BTUs Heat lost through windows = 323 x 6000 x 24 / 2.5 = 18604800 BTUs Heat lost through walls = 1970 x 6000 x 24 / 18 = 15760000 BTUs Heat lost through roof = 1266 x 6000 x 24 / 28 = 6510857.14 BTUs Total heat loss from the house = 18604800 + 15760000 + 6510857.14 = 40875657.14 BTUs
A wall consists of 0.5" wood siding (R = 0.81), 0.75" plywood (R = 0.94), 1.2" of fiberglass (R = 3.7 per inch) and 0.5" plasterboard (R = 0.45). What is the composite R-value of the wall? A ) 5.78 B ) 6.64 C ) 7.1 D ) 5.9
B ) 6.64 Composite R-value = 0.81 + 0.94 + (1.2 x 3.7) + 0.45 = 6.64
Compared to a house built in the 1960's, a house built today has _____. A ) A lesser R-value B ) A greater R-value C ) About the same R-value D ) No R-value
B ) A greater R-value Houses built today are better insulated than the ones built in 1960's
Flat plate collectors are usually placed on the roof or on the ground where there is sunlight. Such collectors are classified as _______. A ) Passive Systems B ) Active Systems C ) Hybrid Systems
B ) Active Systems Flat plate collectors are usually placed on the roof or on the ground where there is sunlight. Such collectors are classified as active system
Heat in a room from an air register moves from warmer areas to cooler areas of the room due to _____. A ) Radiation B ) Convection C ) Conduction
B ) Convection Convection is a process by which energy is transferred by the bulk motion of the fluids (gases or liquids).
One of the heating systems we talked about in this course comprises of a system of ducts. What is the process by which heat is transferred in this system? A ) Conduction B ) Convection C ) Radiation D ) None of the above
B ) Convection Ducts are used to circulate air in the building. Since, air is circulated in the system, heat is transfered by convection.
What is the process by which energy is transferred by the bulk motion of the fluids? A ) Conduction B ) Convection C ) Radiation
B ) Convection Heat transfer by bulk transfer of fluids is by convection
What is the process by which forced-air furnace systems distribute heat? A ) Conduction B ) Convection C ) Radiation D ) None of the above
B ) Convection When air is circulated, heat is transfered by convection.
What is the process by which forced-air furnace systems distribute heat? A ) Conduction B ) Convection C ) Radiation D ) None of the above
B ) Convection heat transfer in fluids occur through a mechanism called convection
Due to convection, a house with an electric radiant system and floors with a high thermal mass can reduce heating costs if the electric company offers "time-of-use" rates. A ) TRUE B ) FALSE
B ) FALSE An electric radiant system heats through radiation, not convection. Refer to screen 14 in 'Lesson 8a - Comparison of Home Heating Systems'
Solar and GHP heating systems have absolutely no impact on the environment. A ) TRUE B ) FALSE
B ) FALSE Both solar and GHP heating systems both require the use of pumps that use electricity. Although the amount is small, it is still electricity, and with generation of electricity, there are emissions.
Solar and GHP heating systems have absolutely no impact on the environment. A ) TRUE B ) FALSE
B ) FALSE Both solar and GHP heating systems both require the use of pumps that use electricity. Although the amount is small, it uses electricity, and with generation of electricity, there are emissions
We know that, electrical resistance heating systems approach an efficiency of 97%. Electrical baseboard heating is more efficient than a heat pump. A ) TRUE B ) FALSE
B ) FALSE Electrical resistance heating systems converts electricity to heat. All the heat is obtained from electricity. But, heat pump heat our house by moving heat from low temperature surrounding to high temperature interior. Electricity is only used to run compressor.
A heat mover speeds up a natural heating process. A ) TRUE B ) FALSE
B ) FALSE False, naturally, heat moves from high to low temperature environment. A heat pump goes against nature, moving the heat from a low to a high temperature environment.
In home heating, if the outside temperature increases, holding the inside temperature constant, the Coefficient of Performance of a heat pump decreases. A ) TRUE B ) FALSE
B ) FALSE False, the COP will increase if the outside temperature increases (see formula).
Ground Source heat pumps are less efficient than air to air heat pumps. A ) TRUE B ) FALSE
B ) FALSE Ground source heat pumps are more efficient than air to air heat pumps
There is no reason to ventilate the attic in the summer if it is well insulated. A ) TRUE B ) FALSE
B ) FALSE Ventilating the attic in the summer lets the hot air to escape.
Horizontal loop Geothermal heat pumps are used when there is less space available A ) TRUE B ) FALSE
B ) FALSE Vertical loop Geothermal heat pumps are used when there is less space available
Horizontal loop geothermal heat pumps are used when there is less space available. A ) TRUE B ) FALSE
B ) FALSE Vertical loop geothermal heat pumps are used when there is less space available
An active system emits more SO2 directly into the environment than a passive system. A ) TRUE B ) FALSE
B ) FALSE both the active and passive systems use solar energy, which do not directly emit SO2 energy into the environment.
In a baseboard radiator, _________increase(s) the surface area, which in turn leads to more efficient heat transfer. A ) Ducts B ) Fins C ) Gas combustion D ) Oil Heating
B ) Fins False, an electric radiant system heats through radiation, not convection.
What is the most commonly used fuel used for residential heating? A ) Oil B ) Gas C ) Electric D ) Coal
B ) Gas Natural Gas, 55% of households use natural gas
The number of degrees the mean outside temperature falls below 65 oF for a given day is given by _____. A ) Heat index B ) HDD C ) CDD D ) AFUE
B ) HDD The HDD indicates how many degrees the mean outside temperature fell below 65ºF for the day
The word insolation is a combination of which of the following words: A ) Instrumental solar insulation B ) Incident solar radiation C ) Intricate solar variation D ) Involved solar saturation
B ) Incident solar radiation Incident solar radiation. Insolation is from Incident Solar Radiation.
What is the physical meaning of the coefficient of performance? A ) It is the amount of work required to move one unit of heat between the reservoirs B ) It is the amount of heat moved between the reservoirs for every unit of work done C ) It is the amount of heat needed to produce one unit of work D ) It is the amount of work needed to produce one unit of heat
B ) It is the amount of heat moved between the reservoirs for every unit of work done Coefficient of performance is the amount of work required to move one unit of heat between the reservoirs
What is the physical meaning of coefficient of performance? A ) It is the amount of heat needed to produce one unit of work B ) It is the amount of heat moved between the reservoirs for every unit of work done C ) It is the amount of work required to move one unit of heat between the reservoirs D ) It is the amount of work needed to produce one unit of heat
B ) It is the amount of heat moved between the reservoirs for every unit of work done coefficient of performance is the amount of heat moved between the reservoirs for every unit of work done
What is the mechanism by which heat is transferred without the help of any medium (molecules or atoms)? A ) Convection B ) Radiation C ) Conduction
B ) Radiation Radiation is transfer of heat through electromagnetic radiation. In gases, liquids, and solids, energy is transferred by the molecules with or without their physical movement (convection or conduction).
Nearly one half of the energy used at home is for _____. A ) stoves B ) Space heating and cooling C ) refrigerators D ) lighting
B ) Space heating and cooling Nearly 47% of the energy at home is used for home heating and cooling
Keep the draperies and shades on your south-facing windows open during a _____________ day to cut down energy costs. A ) Summer B ) Winter
B ) Winter Keep the draperies and shades on your south-facing windows open during a winter day to cut down energy costs
The circulation of air due to temperature differences in a room is called a _____. A ) conductive loop B ) convective loop C ) circulation loop D ) heating loop
B ) convective loop The circulation of air due to temperature differences in a room is called a convective loop
In heating mode, when the refrigerant liquid moves past the expansion valve it ______. A ) condenses, absorbing heat from the outside B ) evaporates, absorbing heat from the outside C ) evaporates, giving off heat to the outside D ) condenses, giving off heat to the outside
B ) evaporates, absorbing heat from the outside In heating mode, when the refrigerant liquid moves past the expansion valve it evaporates, absorbing heat from the outside
The compressor of a heat pump system ___________ the pressure of the refrigerant, ________ its temperature. A ) increases, lowering B ) increases, raising C ) decreases, lowering D ) decreases, raising
B ) increases, raising The compressor increases the refrigerants pressure, increasing its temperature.
If a heat pump is used to heat a house in the winter, how will the Coefficient of Performance be affected as the outside temperature drops? A ) it increases B ) it decreases C ) it stays the same D ) it may become negative
B ) it decreases COP = Thot/(Thot-Tcold) When Tcold is reduced, COP decreases
If a heat pump is used to heat a house in the winter, how will the Coefficient of Performance be affected if the inside set temperature is changed from 70 F to 65 F? A ) it stays the same B ) it increases C ) it may become negative D ) it decreases
B ) it increases
When a heat pump is used to heat a house in the winter, how will the Coefficient of Performance be affected if the outside temperature increases? A ) it decreases B ) it increases C ) it may become negative D ) it stays the same
B ) it increases
A heat pump with a COP of 5 maintains an indoor temperature of 65ºF. What is the temperature outside? A ) 20ºF B ) minus 40ºF C ) minus 30ºF D ) 50ºF
B ) minus 40ºF COP = Thot/(Thot-Tcold) Thot = 65 F = (65-32)x5/9 C = 18.33 C = 18.33 + 273 K = 291.33 K 5 = 291.33/(291.33-Tcold) Tcold = 233 K = 233 - 273 C = -40 C = (-40x9/5)+32 F = -40 F
Opening the drapes of windows on which side of the house will help reduce heating costs? A ) north B ) south C ) east D ) west
B ) south Opening the drapes of windows on south side of the house will help reduce heating costs
What is the average cost of electricity in the US? A ) $8.0/kWh B ) $0.06/MWh C ) $80/MWh D ) $60/kWh
C ) $80/MWh Average cost of electricity in the US is $0.08 per kWh. This is same as $80 per MWh
A wall consists of 0.5" wood siding (R = 0.81), 0.75" plywood (R = 0.94), 2.4" of fiberglass (R = 3.7 per inch) and 0.5" plasterboard (R = 0.45). What is the composite R-value of the wall? A ) 8.3 B ) 5.9 C ) 11.08 D ) 10.22
C ) 11.08 Composite R-value = 0.81 + 0.94 + (2.4 x 3.7) + 0.45 = 11.08
A room has a wall with an R value of 18 F sq.ft. hr/BTU. The room is 18 feet long and 9 feet wide with walls that are 9 ft high. On a particular day the average outside temperature is 29 degrees F. How much heat is transferred through the walls on that day (in BTUs)? A ) 1296 BTUs B ) 69984 BTUs C ) 23328 BTUs D ) 972 BTUs
C ) 23328 BTUs Total area of walls = 2 ((18 x 9) + (9 x 9)) = 486 sq.ft HDD = 65-29 = 36 oF Heat transferred = 486 x 36 x 24 / 18 = 23328 BTUs
A house in State College, PA (HDD=6000) has 344 ft2 of windows with R value = 2.5, 1804 ft2 of walls with R value = 18, and 1101 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)? A ) 1662861.9 BTUs B ) 14566670.29 BTUs C ) 39908685.71 BTUs D ) 6651.45 BTUs
C ) 39908685.71 BTUs Heat lost through windows = 344 x 6000 x 24 / 2.5 = 19814400 BTUs Heat lost through walls = 1804 x 6000 x 24 / 18 = 14432000 BTUs Heat lost through roof = 1101 x 6000 x 24 / 28 = 5662285.71 BTUs Total heat loss from the house = 19814400 + 14432000 + 5662285.71 = 39908685.71 BTUs
A house in State College, PA (HDD=6000) has 347 ft2 of windows with R value = 2.5, 1926 ft2 of walls with R value = 18, and 1212 ft2 of roof with an R-value = 28. What is the total heat loss from the house for the season (in BTUs)? A ) 6781621.62 BTUs B ) 92572144457.14 BTUs C ) 41628342.86 BTUs D ) 1734514.29 BTUs
C ) 41628342.86 BTUs Heat lost through windows = 347 x 6000 x 24 / 2.5 = 19987200 BTUs Heat lost through walls = 1926 x 6000 x 24 / 18 = 15408000 BTUs Heat lost through roof = 1212 x 6000 x 24 / 28 = 6333142 BTUs Total heat loss from the house = 19987200 + 15408000 + 6233142.85 = 41628342.85 BTUs
146 CCF of natural gas is equivalent to how many kWh of Electricity? A ) 427.9 KWH B ) 42.79 KWH C ) 4279.02 KWH D ) 42790.15 KWH
C ) 4279.02 KWH We know that, 1 CCF = 100,000 BTU & 1 KWH = 3412 BTU ' 146 CCF = 146 CCF x 100,000 BTU / 1 CCF x 1 KWH / 3412 BTU = 4279.015 KWH
What is the typical cost of natural gas per million BTUs? A ) 0.06 B ) 0.5 C ) 5 D ) 60
C ) 5
The temperature inside a home remains at 70°F. If on Tuesday the temperature outside is 55°F, but then on Wednesday the temperature outside is 35°F, what is the percent change in COP? (Round your answer to the nearest whole number) A ) 45% decrease B ) 75% increase C ) 57% decrease D ) 22% increase
C ) 57% decrease 57% decrease. By plugging the numbers into the COP equation, it is found that an outside temperature of 55°F produces a COP of 35.3 and an outside temperature of 35°F produces a COP of 15.13. Then finding the percent change from the first to the second results in -59%.
Katy is planning on adding additional insulation to her roof, which costs $2651. It is estimated that she can save $330/year on energy costs from this modification. What is the pay back period in years? A ) 0.1 Years B ) 3.3 Years C ) 8 Years
C ) 8 Years Pay back period = 2651/330 = 8.03 yrs
Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1017 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $616. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $15.6/MCF. Assuming an AFUE of 88.1%, how long will it take Dave to recover his investment (in years)? A ) 0.9 Years B ) 886.8 Years C ) 8.9 Years D ) 9019.2 Years
C ) 8.9 Years Cost of insulation = 616 / 1017 = 0.6057 $/sq.ft Cost of energy = 15.6 / 1,000,000 = 0.0000156 $/BTU Time to recover investment = (0.6057 x 16 x 28 x 0.881) / (0.0000156 x (28 - 16) x 6000 x 24) = 8.86 yrs
Which one of the following devices may heat as well as cool a house? A ) A Furnace B ) A Radiator C ) A Heat Pump D ) A Solar Panel
C ) A Heat Pump Heat pumps may be used to either heat or cool a house based on the season
AFUE stands for _____. A ) American Fuel Utilization Efficiency B ) All Fuel Utilization C ) Annual Fuel Utilization Efficiency D ) After Fuel Utilization
C ) Annual Fuel Utilization Efficiency AFUE (Annual Fuel Utilization Efficiency)
The work (energy) input to a heat pump system is at the _____. A ) Condenser coil B ) Expansion Valve C ) Compressor D ) Evaporator coil
C ) Compressor The work (energy) input to a heat pump system is at the compressor
A process by which energy is transferred as the vibrations of one molecule are passed on to the next, but there is no movement of energetic atoms or molecules themselves is called _____. A ) Convection B ) Radiation C ) Conduction
C ) Conduction Conduction a process by which energy is conducted down the rod as the vibrations of one molecule are passed to the next, but there is no movement of energetic atoms or molecules.
Which of the following sources of energy is the most efficient for heating systems? A ) Coal B ) Wood C ) Electricity D ) Oil E ) Natural Gas
C ) Electricity Electric heaters are the most efficient among heating systems with an efficiency as high as 98%.
Which one of the following energy sources is used by the most efficient heating systems? A ) Wood B ) Oil C ) Electricity D ) Natural Gas E ) Coal
C ) Electricity Electric resistance heating is the most efficient heating system.
What type of air system is most commonly used in central heating and cooling systems? A ) Hydronic B ) Electric Resistance C ) Forced Air Duct D ) Radiant baseboard
C ) Forced Air Duct Forced air duct is the most commonly used in central heating and cooling system
Installation of a GHP costs $8,500, whereas the installation of a forced air system costs $4,000. The average cost of heating using a GHP is $55/month and the average cost of heating using a forced air system costs $145/month. After 5 years, which is cheaper, and by how much? A ) forced air, $750 B ) GHP, $300 C ) GHP, $900 D ) forced air, $1050
C ) GHP, $900 GHP, $900. Find each total cost by using: installation + (cost/month*12months/year*5years). Then subtract the lowest from the highest.
What is the most commonly used fuel for residential heating? A ) Electric B ) Coal C ) Gas D ) Oil
C ) Gas Natural Gas, 55% of households use natural gas. Refer to screen 3 in 'Lesson 8a - Comparison of Home Heating Systems'
Most of the energy used at home is used for _____. A ) Lighting B ) Appliances C ) Heating D ) Cooling
C ) Heating Most of the energy used at home is used for heating
Which one of the following is true about a geothermal heat pump? A ) It can provide heat in winter but cannot cool the house in summer B ) Its operating costs are high for its usage in the long run C ) It saves energy and the environment D ) It requires a lot of maintenance
C ) It saves energy and the environment geothermal heat pump provides heat in winter and cool the house in summer. It saves energy and the environment. It requires very little maintenance
What is the most common fuel for home heating in the US? A ) Coal B ) Oil C ) Natural Gas D ) Electricity
C ) Natural Gas Natural gas is the most common fuel used for residential heating in US
On cloudless nights, heat escapes from our planet and goes into space. What is this due to? A ) Conduction B ) Convection C ) Radiation D ) Radiation and Convection
C ) Radiation
You are warmed by the sun. This is an example of heat transfer by _____. A ) Conduction B ) Convection C ) Radiation D ) None of the above
C ) Radiation Radiation is the only mode of heat transfer which does not require a medium. Heat from the sun reaches the earth through space by radiation.
What is the process in which heat is transferred through electromagnetic radiation? A ) Conduction B ) Convection C ) Radiation
C ) Radiation Radiation is transfer of heat through electromagnetic radiation.
A thermos bottle has a shiny interior. What type of heat transfer does this prevent? A ) Conduction B ) Convection C ) Radiation
C ) Radiation Radiation is transfer of heat through electromagnetic radiation.A shiny surface reflects any incident radiation.
High temperature, high pressure refrigerant comes out of the compressor and _____. A ) condenses, absorbing heat from the inside B ) evaporates, giving off heat to the inside C ) condenses, giving off heat to the inside D ) evaporates, absorbing heat from the inside
C ) condenses, giving off heat to the inside High temperature, high pressure refrigerant comes out of the compressor and condenses, giving off heat to the inside
A solar collector's efficiency increases as ______. A ) the sun sets B ) insolation increases (useful energy delivered remains constant) C ) useful energy delivered increases (insolation remains constant) D ) the sun rises
C ) useful energy delivered increases (insolation remains constant) Useful energy delivered increases. Based on the equation: Collector's Efficiency = Useful energy delivered/insolation on collector*100, and there fore if the useful energy delivered increases, the collector's efficiency will increase
A heat mover_____. A ) uses work to move heat from a high temperature reservoir to a low temperature reservoir B ) uses heat moving from a low temperature reservoir to a high temperature reservoir to produce work C ) uses work to move heat from a low temperature reservoir to a high temperature reservoir D ) uses heat moving from a high temperature reservoir to a low temperature reservoir to produce work
C ) uses work to move heat from a low temperature reservoir to a high temperature reservoir A heat mover uses work to move heat from a low temperature reservoir to a high temperature reservoir
A heat pump (heating) with a COP of 3.0 maintains an indoor temperature of 67 degrees F. What is the outside temperature (in oF)? A ) 108 F B ) -78 F C ) 78 F D ) -108 F
D ) -108 F 67 oF = (67 - 32) 5 / 9 oC = 19.44oC = 19.44 + 273 K= 292.44 K ' 3 = 292.44 / (292.44 - tcold) ' tcold = 292.44 - 292.44 / 3 = 194.96 K = 194.96 - 273 oC = -78.04 oC = (-78.04 x 9 / 5) + 32 oF = -108.48 oF
A heat pump (heating) with a COP of 6.7 maintains an indoor temperature of 65 degrees F. What is the outside temperature (in oF)? A ) 13 F B ) 25 F C ) -25 F D ) -13 F
D ) -13 F 65 oF = (65 - 32) 5 / 9 oC = 18.33oC = 18.33 + 273 K= 291.33 K ' 6.7 = 291.33 / (291.33 - tcold) ' tcold = 291.33 - 291.33 / 6.7 = 247.84 K = 247.84 - 273 oC = -25.16 oC = (-25.16 x 9 / 5) + 32 oF = -13.29 oF
The heat loss through a window (R-2) is 10 MMBTU/year. Calculate the payback period (in years) if Argon is filled in the window to increase the effective R-value of the window to 7. Assume heating price to be $10/MMBTU and the cost for filling Argon is $20. A ) 0.7 years B ) -0.08 years C ) 0.21 years D ) 0.28 years
D ) 0.28 years Heat lost through new window per year = (10 x 2) / 7 = 2.84 MMBTUs/yr Reduction in heat lost per year = 10 - 2.84 = 7.16 MMBTUs/yr Savings in energy cost per year = 7.16 x 10 = $71.6 Payback period = 20 / 71.6 = 0.28 yrs
What is the typical range for the COP for heat pumps? A ) 90-100 B ) 200+ C ) 300+ D ) 1.5-3.5
D ) 1.5-3.5 Cop for heat pump typically ranges between 1.5-3.5
Dave has a home in Pittsburgh, PA (HDD = 6,000) with a roof area of 1182 ft2. He is considering upgrading the insulation from R-16 to R-28. The estimate for this job from the contractor is $638. Dave's home is heated with natural gas. Last year, the average price he paid for natural gas was $12.9/MCF. Assuming an AFUE of 94.6%, how long will it take Dave to recover his investment (in years)? A ) 12129.9 Years B ) 1026.2 Years C ) 1 Years D ) 10.3 Years
D ) 10.3 Years Cost of insulation = 638 / 1182 = 0.5397 $/sq.ft Cost of energy = 12.9 / 1,000,000 = 0.0000129 $/BTU Time to recover investment = (0.5397 x 16 x 28 x 0.946) / (0.0000129 x (28 - 16) x 6000 x 24) = 10.26 yrs
A wall consists of 0.5" wood siding (R = 0.81), 0.75" plywood (R = 0.94), 3.6" of fiberglass (R = 3.7 per inch) and 0.5" plasterboard (R = 0.45). What is the composite R-value of the wall? A ) 5.9 B ) 14.66 C ) 9.5 D ) 15.52
D ) 15.52 Composite R-value = 0.81 + 0.94 + (3.6 x 3.7) + 0.45 = 15.52
After a house is built, the easiest place to insulate a house is/are _____. A ) Walls B ) Roof C ) Basement walls D ) Attic
D ) Attic Attic is the place that can be easily insulated after a house has been built.
In a baseboard radiator _____ increase(s) the surface area, which in turn leads to more efficient heat transfer." A ) Ducts B ) Oil Heating C ) Gas combustion D ) Fins
D ) Fins In a baseboard radiator fins increase the surface area, which in turn leads to more efficient heat transfer.
Which term is used to define the energy efficiency of a central air-to-air Heat Pump? A ) AFUE B ) EER C ) EF D ) HSPF
D ) HSPF HSPF is used to define the energy efficiency of a central air-to-air Heat Pump
Most of the energy used at home is used for _____. A ) Appliances B ) Lighting C ) Cooling D ) Heating
D ) Heating Nearly 47% of the energy at home is used for home heating and cooling Refer to screen 4 in 'Lesson 7a - Residential Heat Loss'
Bleeding air from the pipes of a hydronic radiant baseboard heating system will _____. A ) Decrease efficiency B ) Increase amount of noise made by clanging pipes C ) Improve air circulation in the house D ) Increase efficiency
D ) Increase efficiency Air has a lower capacity to hold heat. Thus, air in the pipes of a hydronic radiant baseboard heating system reduces the amount of heat that can be carried in the pipes and transfered to the room. Thus bleeding air will improve the efficiency of the system.
What happens to the high temperature, high pressure refrigerant after it comes out of the compressor of a heat pump (heating mode)? A ) It evaporates in the coil, giving off heat to the inside B ) It evaporates in the coil, absorbing heat from the inside C ) It condenses in the coil, absorbing heat from the inside D ) It condenses in the coil, giving off heat to the inside
D ) It condenses in the coil, giving off heat to the inside In heating mode, high temperature, high pressure refrigerant comes out of the compressor and condenses, giving off heat to the inside
Which of the following is not true about a geothermal heat pump? A ) it provides reduced or free hot water B ) it requires little maintenance C ) it saves energy and is evironmentally friendly D ) Its cost is a hindrance for their development
D ) Its cost is a hindrance for their development Geothermal heat pump provides reduced cost or free hot water. It requires little maintenance and saves energy.
Which one of the following will have a negative impact on the home heating efficiency? A ) Closing off rooms that aren't in use. B ) Frequently clean your furnace filter. C ) Fix cracks in walls and floor. D ) Open front door in winter to filter and clean warm air.
D ) Open front door in winter to filter and clean warm air. Open front doorIn the winter, it is best to keep the outside doors shut or close them quickly so the heat doesn't escape.
All of the following are examples of ways to improve energy efficiency of heating systems, except _______. A ) Frequently cleaning the furnace filter. B ) Closing off rooms that aren't in use. C ) Fixing cracks in the walls and floor. D ) Opening the front door in winter to filter and clean warm air.
D ) Opening the front door in winter to filter and clean warm air. Open front door. In the winter, it is best to keep the outside doors shut or close them quickly so the heat doesn't escape.
On cloudless nights, heat escapes from our planet and goes into space by _____. A ) Radiation and Convection B ) Convection C ) Conduction D ) Radiation
D ) Radiation Radiation is the only type of heat of transfer that doesn't require a medium.
Which term is used to describe the efficiency of a Central Air Conditioner? A ) AFUE B ) EER C ) EF D ) SEER
D ) SEER SEER is used to describe the efficiency of a central air conditioner
Of the following, which one is not an advantage of forced air heating systems? A ) Rooms are heated quickly B ) The system isn't very complicated C ) Ducts can easily be used for A/C in the summer D ) They usually have a very high efficiency (80-90%)
D ) They usually have a very high efficiency (80-90%) The efficiency is around 50%.
A "desuperheater" can provide a homeowner with _____. A ) forced air heat B ) a filtrated heating system C ) air conditioning D ) free or reduced cost hot water
D ) free or reduced cost hot water Free or reduced cost hot water. A "desuperheater" transfers excess heat from the heat pump's compressor into the hot water tank.
Of the following sources, where does a typical home loses most heat? A ) Windows B ) Doors C ) Basement D ) Roof E ) Cracks in walls, windows and doors
E ) Cracks in walls, windows and doors Cracks in walls, windows and doors is where a typical house losed most heat
Because of which two processes do you feel the heat when you are standing next to a wood stove? A ) Conduction B ) Convection C ) Radiation D ) Radiation and conduction E ) Radiation and convection
E ) Radiation and convection
