Zanotti Zer0 120, Руководство по ремонту

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3.2.3 Defrost and Heat
When low-pressure refrigerant vapor is compressed to a high-pressure the temperature rises and the mechanical
energy is transferred to the gas as it is being compressed. This energy is referred to as the “heat of compression”
and is used as the source of heat during the heating or defrost cycle.
When the microprocessor activates heating or defrost, the hot gas solenoid valve energizes, opening a port which
allows heated refrigerant vapor to flow directly to the evaporator coil. The microprocessor also activates the
condenser inlet solenoid valve, closing the flow of refrigerant to the condenser. Allowing all the hot gas to enter the
evaporator. The main difference between heating and defrosting is that when in heating mode the evaporator fans
continue to run thus circulating the air throughout the compartment to heat the product. When in defrost, the
evaporator fans stop, thus allowing the heated vapor to defrost any ice build-up on the coil.
The defrost cycle can be initiated any time the evaporator coil temperature is below 35°F. Defrost is initiated
automatically by the defrost timer, or manually by pressing the manual defrost switch. The defrost relay energizes
the hot gas solenoid valve (and the condenser solenoid valve on units equipped with the heat option) to route hot
refrigerant gas to the evaporator when PR is energized. The defrost relay also interrupts power to the evaporator
and condenser fans during defrost.
The defrost cycle will continue until the defrost interval has ended.
Figure 7 - Z120 Heat/Defrost Mode Refrigeration Diagram