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WATER-TO-WATER GEOTHERMAL HEAT PUMP SYSTEMS
ANSWERS TO TEXTBOOK QUESTIONS AND EXERCISES
1. Water-to-water heat pumps use many of the same components as air-to-water heat
pumps, such as a compressor, refrigerant-to-water heat exchanger, reversing valve, and
2. If the fluid flow rate from the earth loop to the evaporator in a water-to-water heat pump
5. Five to ten percent of the total thermal energy in the hot refrigerant gas leaving the
7. (a) 109.1°F
9. The net COP as calculated based on the ANSI 13256-2 standard is 4.24. This is a bit
11. The buffer tank is necessary because of the variation in the demand load. The presence of
12. 16.4 minutes
13. (a) it doubles
17. 7 gpm
21. (a) PEX tubing cannot be joined using butt fusion because it is a thermoset polymer,
23. (a) The header piping size may remain constant if the parallel branches join a header at
25. A cold ring clamp should always be used when making a socket fusion weld in HDPE
27. An expansion tank reduces pressure variations in the circuit, which lessens the potential
28. (a) When the heat pump is operating in a heating mode, the internal volume of the HDPE
29. (a) 0.67 gal
33. Because the sizing calculations are based on the expansion tank being half filled with
fluid.
34. A buffer tank is not needed in a single-zone system if heating capacity of the heat pump
36. Because it has only one zone of cooling
39. The repeat cycle timer relay is used to create a 3-minute “sampling period” every 15