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quiz lesson 9

# A higher eciency than roof air condi3oners roof

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Unformatted text preview: ) The temperature decreases temperature of refrigerant in the expansion valve decreases Each degree senng below 78ºF will increase your energy consump3on by approximately 8 percent. Correct A ) T RUE Each degree senng below 78ºF will increase your energy consump3on by approximately 8 percent If the owner replaces his old 5 ton air condi3oner (SEER=9) with a new 5 ton air condi3oner (SEER=16), which costs \$462 more, what is the payback period? Assume that the air condi3oner is operated for about 2000 hrs in a year and the cost of electricity is 11 cents per kWh. (5 Points) Correct A ) 0.72 years We know that, 1 ton of air condi3oning = 12000 BTU/hr Old air condi3oner Power consump3on = 5 x 12000 / 9 = 6666.666 wa\s Energy cost = 6666.666 x 2000 / 1000 x 11 / 100 = \$1466.66 New air condi3oner Power consump3on = 5 x 12000 / 16 = 3750 wa\s Energy cost = 3750 x 2000 / 1000 x 11 / 100 = \$825 Savings in energy cost = 1466.66 - 825 = \$641.66 Pay Back period = 462 / 641.66 = 0.72 yrs If the owner replaces his old 4 ton air condi3oner (SEER=7) with a new 4 ton air condi3oner (SEER=13), which costs \$453 more, what is the payback period? Assume that the air condi3oner is operated for about 2000 hrs in a year and the cost of electricity is 10 cents per kWh. Correct C ) 0.72 years We know that, 1 ton of air condi3oning = 12000 BTU/hr Old air condi3oner Power consump3on = 4 x 12000 / 7 = 6857.142 wa\s Energy cost = 6857.142 x 2000 / 1000 x 10 / 100 = \$1371.42 New air condi3oner Power consump3on = 4 x 12000 / 13 = 3692.307 wa\s Energy cost = 3692.307 x 2000 / 1000 x 10 / 100 = \$738.46 Savings in energy cost = 1371.42 - 738.46 = \$632.96 Pay Back period = 453 / 632.96 = 0.715 yrs Which is more eﬃcient, an air condi3oner with E ER 8.0 or an air condi3oner with S EER 9.7? Correct B ) S EER 9.7 _____________ rela3ve humidity feels uncomfortable. Correct A ) Both very high and very low Both very high and very low rela3ve humidity feels uncomfortable Floor insula3on has li\le or no eﬀect on cooling. Correct A ) T RUE Floor insula3on has li\le or no eﬀect on cooling. Eﬀec3ve shading can be provided by trees and other vegeta3on Correct A ) T RUE Eﬀec3ve shad...
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