It includes a hand-operated valve to help give a controllable water flow and a simple return pipe, both colour-coded. The Base Unit’s water system connects to a suitable cold water supply and drain. It provides cold water and heater power to the optional experiments and all the instruments needed to measure their performance. The outdoor coil is now a condenser and the indoor coil behaves as an evaporator.Īfter the ice has been defrosted, the system will switch back to the heat mode to heat up the room.The Base Unit (TD1002) is the core of the TD1002 range. The 4-way-valve will be switched ON, the outdoor fan OFF and indoor fan OFF(depending on design) but the compressor will be operating.ĭuring this time, the heat from the inside the building will be extracted to the outside to heat up the ice. The control can be a defroster or directly from the main controller.ĭuring defrosting, the unit is working in cooling mode. When this happens and by measuring the temperature and the time of the freezing, the defrost mode will be initiated by the control. When the outside temperature begins to drop below 50☏(10 ☌), the coil will begin to freeze. When running in heat mode, the outdoor coil operates as an evaporator. Heat Pump Package Unit - Defrosting Cycle However, it should be a temporary measure as the COP of the auxiliary heater is not as good as when running the heat pump system. If the heat pump fails, the Emergency Heat mode can be used to heat up the room. In order to continue to provide heating to the room, the auxiliary heater from electric, oil or gas will turn ON.ĭepending on the controls used by the manufacturer, using an outdoor thermostat to control the auxiliary heater is common. When the outdoor temperature continues to drop, the amount of heat that can be transferred begins to reduce. The system is now operating in heating mode. When the room temperature is lower than the set temperature by a certain degree(depending on the thermostat used), the indoor blower fan, outdoor fan and compressor will then turn ON.Īs the 4-way-valve is OFF, the hot air from the compressor is directed to the indoor coil. Inverter type compressor requires a much more complicated electronic controls and cannot be controlled by using the normal thermostat. The information discussed here is valid for the ON/OFF type compressor and not the inverter type. Once this happens, the compressor, outdoor fan and indoor blower fan(will continue to on for some design) will turn OFF. The system will continue to operate until the room temperature is below the set temperature by a certain degree. When this happen, the system is operating in the cooling mode in which the hot gas from the compressor is diverted to the outdoor coil by the 4-way-valve. The indoor blower fan, the outdoor fan and the compressor outputs will than turn ON. When the room temperature is higher than the set temperature, the output that controls the 4-way-valve will turn ON. Heat Pump Package Unit - Cooling During Summerĭuring warmer days, the thermostat is set to COOL mode and the set temperature is set as desired such as 75☏ (24☌). Controls may vary depending on the design of the manufacturers. Here are the basic working principles of a typical package unit. The conditioned air is then channeled to the various rooms by using ducting. When you encounter the word "package", it means that all the components needed for the unit to function are enclosed in a single housing.
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