Handbook of air conditioning and refrigeration / Shan K

System Characteristics
Applications
REFERENCES
Efficiency as of October 29, 2001 for packaged terminal heat pumps:
EER � 12.3 � (26.3)
For new installed packaged terminal heat pumps in heating mode operation, their minimum efficiency
requirements can be calculated as:
0.213Qrc 1000
Efficiency as of October 29, 2001:
AC SYSTEMS: SYSTEM CLASSIFICATION, SELECTION 26.15
COP � 2.9 � 0.026Q rc
1000
COP � 3.2 � 0.026Q rc
1000
(26.4)
where Q rc � cooling capacity, Btu/h. For factory-labeled replacement of packaged terminal air
conditioners and heat pumps, only their required minimum EER or COP will be slighly lower as of
October 29, 2001. Refer to ASHRAE/IESNA Standard 90.1-1999 for details.
System characteristics of PTACs and PTHPs are listed in Table 26.1. Compare the system characteristics
of RACs with PTACs, also RHPs with PTHPs; they are quite similar, except for the following
differences:
● RACs and RHPs are often window-mounted, whereas PTACs and PTHPs are mounted through
the wall.
● PTACs and PTHPs have a better appearance on the building facade outdoors as well as on the
front panel indoors.
● Some PTACs and PTHPs offer more control functions such as automatic changeover from cooling
mode operation to heating mode operation, and vice versa, evaporator freeze-up protection,
limited operation when zone temperature limits are exceeded, thermostat set points adjustments
during the unoccupied period, and fault detection and diagnostics.
According to Air Conditioning, Heating & Refrigeration News on April 15, 1996, PTAC shipments
in 1994 in the United States comprised 75,000 units and PTHPs 100,000 units. PTACs and PTHPs
are widely used in commercial buildings. They are mostly adopted in relatively small zones in the
perimeter zones of buildings such as hotels, motels, apartments, nursing homes, and offices.
ASHRAE, ASHRAE Handbook 1996, HVAC Systems and Equipment, ASHRAE Inc., Atlanta, GA, 1996.
ASHRAE, ASHRAE Handbook 1999, HVAC Applications, Atlanta, GA, 1999.
ASHRAE, ASHRAE/IES Standard 90.1-1999 Energy Standard for Buildings Except New Low-Rise Residential
Buildings, Atlanta, GA, 1999.
DOE/EIA, 1998 Nonresidential Building Energy Consumption Survey: Commercial Buildings Consumption
and Expenditure 1995, DOE/EIA-0318 (95).
Gladstone, J., and Humphreys, K. K., Mechanical Estimating Guidebook, McGraw-Hill, New York, 1995.