Modern Refrigeration 21st Edition

Question 1

Your customer has an existing attic with a U-factor of .04. R-30 has been added to the attic so the new U-factor of the ceiling is?

Answer 1

.018

R = 1 ÷ U-factor
R = 1 ÷ .04
R = 25
R25 + R30 = R55

U-factor = 1 ÷ R-Value
U-factor = 1 ÷ 55
U-factor = .018

Pg. 1315 Modern Refrigeration

Question 2

The term __________ indicates that a portion of the liquid refrigerant in circulation that turns into a vapor as it passes through the refrigerant control device.

Answer 2

Flash Gas

Glossary Modern Refrigeration

Question 3

When trying to reduce vibration from a commercial compressor, vibration isolators should be installed. How many vibration isolators should be installed in each line when you have horizontal and vertical vibration?

Answer 3

2 in each line

Pg. 1371 and Pg. 462 Modern Refrigeration

Question 4

An externally equalized thermostatic expansion valve should always be used when the pressure drop across the evaporator coil exceeds ________psi.

Answer 4

4psi

Pg. 479 Modern Refrigeration

Question 5

How many British Thermal Units does it take to melt 2,000lbs of ice in a 24 hour period?

Answer 5

12,000BTU

Pg. 66 Modern Refrigeration

Question 6

What is the critical temperature of R-410A Refrigerant?

Answer 6

72.1⁰C

Pg. 1502 Modern Refrigeration

Question 7

When servicing disposable filters in HVAC systems, the filter must be replaced when the pressure drop across the filter exceeds ______% of the pressure drop across the fan.

Answer 7

25%

Pg. 771 Modern Refrigeration

Question 8

An air conditioning installation has a vibration in the refrigerant lines that is being transmitted to the structure. Suitable vibration isolators have been installed. What other option would help eliminate the line vibration?

Answer 8

A horizontal loop of soft copper in the suction line and a vertical loop in the liquid line.

Pg. 462 and Pg. 1372 Modern Refrigeration

Question 9

Refrigerant at a temperature below it’s saturated temperature is said to be?

Answer 9

Subcooled

Pg. 1570 Modern Refrigeration

Question 10

The boiling point of water is ________⁰C

Answer 10

100⁰C

Pg. 58 Modern Refrigeration

Question 11

A/An _________ is the component in a heat pump that changes liquid refrigerant into a vapor when heat is absorbed into the system in the heating cycle.

Answer 11

Outdoor coil.

Pg. 1050 Modern Refrigeration