APPENDIX A (Continued)
The refrigeration heat recovery method is suitable when
a refrigeration-type compressor is used, and when simultaneous
heating and cooling of one or more spaces is required.
Conventional Refrigeration Machine Method. The
conventional refrigeration machine method uses a direct expansion
cooling coil in conjunction with either a hot water or
refrigerant coil. See Figure A-11 and Figure A-12.
A hot water heating system extracts heat from the
refrigerant through a heat exchanger. For direct air heating, a
condensing refrigerant coil is used instead of a heat exchanger
and water pump. This method is used for lower capacity systems
to reject heat when space heating is not required.
Internal Source Heat Pump Method.
See Figure A-13.
Single Bundle Condenser Water Circuit Method. The
single bundle condenser water circuit method uses a cooling coil
in conjunction with a hot water system for heat recovery. When
space heating is not required, heat is rejected through an
evaporative cooler, a heat exchanger, and an open cooling tower.
Application of this system is limited to a maximum
water temperature of 110 degrees F. This system can be used with
any compressor type. See Figure A-14.
Double Bundle Condenser Water Circuit Method. The
double bundle condenser water circuit method incorporates two
and one for the cooling tower system. Water temperatures up to
125 degrees F can be obtained by using higher compressor speeds,
larger impellers, or more than one stage. See Figure A-15.
Selection of a heat recovery machine is critical
because relatively high condensing temperatures are required. To
prevent surging of the compressor under operating load and
required condenser water conditions, lower the condensing
temperatures under partial load conditions. Units shall be
selected to operate above 50 percent of full load at all times.
Storage tanks may be incorporated into a double bundle condenser
water circuit system.