Reversible air-conditioning
On Fig. 27.1 simple reversible air-to-air system are shown in the heating mode. Hot gas from the compressor, aimed at the indoor unit acting as a condenser, providing heat to the building. The condensed liquid flows through the non-return valve (HP) and the device through an expansion valve, where it evaporates, cooling the air outside. When the piston in the reversing valve is moved to the left, ports, will be changed so that the flow in the system is restored and the device cools the building.
Hardware that can provide either cooling or heating is gaining popularity with the air/air/water and water/water use. Some air/air packaged systems are able to provide simultaneous heating and cooling an example of this type is described in Chapter 25. Air/water chillers can use the water circuits and fan-coils, which can operate both on cooled or heated water. Water/water systems cover a very large range of sizes and settings can have multiple packaged chillers with piped water schemes for heating and cooling simultaneously to different sections of the building on demand. A vivid example of the installation of this type describes McLean (2006)...
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Air-Conditioning