Views: 362 Author: Site Editor Publish Time: 2019-12-05 Origin: Site
Since the advent of air source heat pump (ASHP), it has been famous for its energy-saving and safety. It can be said that there is almost no threat to personal safety. Now this is the question: do you know how ASHP is designed to keep its safety? This article will introduce several protection functions of air source heat pump.
High pressure protection refers to the function implemented by the high-pressure protector. When the condenser's temperature is too high, the unit will stop the operation of the compressor. The high-pressure operation is very harmful to the unit, which will cause high exhaust temperature, increased operation current and reduced efficiency. The compressor's temperature will become too high, the friction part of the compressor will get deteriorated due to the sharp drop of the oil viscosity, and the operation life will be shortened.
When the temperature of engine oil and Freon exceeds 135℃, the phenomenon of carbon dissociation may also occur, which will cause irreversible chemical changes and damage the unit. Thus, air source heat pump water heater must have the function of high pressure automatic protection.
This protection is implemented by the low-pressure protector. When the pressure of the evaporator is too low, the heating capacity of the heat pump will decrease, the exhaust temperature will decline, and even the unit will lose its heating capacity. Some frost might appear at the evaporator in advance. Because of the decrease of the working quality, the friction heat of the compressor cannot be taken out. As a result, the temperature of the compressor body is increased and the wear is intensified.
When the current through the compressor coil increases abnormally and exceeds the maximum current allowed by the compressor, the over current protector acts to force the compressor to stop running. This generally indicates a serious compressor failure. When this phenomenon occurs, it is necessary to first check whether the winding of the compressor is abnormal, and check whether there is turn-to-turn short circuit, short circuit and compressor stuck.
Whether there is water flow in the heat pump water heater is also a necessary condition for the unit to start. The purpose is to prevent the operation of the water pump when it is out of water. Also this function can avoid high condenser temperature as well as other failures. When the heat pump receives the start command, it will first detect whether the water flow switch is on. Only if there is water flow can the switch be turned on, and then other items will be detected in turn. The compressor will be started once everything is normal.
Whether the heat pump works or not must have the water temperature signal input, so when the unit cannot detect the signal or the signal drifts and changes to a large extent beyond the range permitted by the controller, the automatic controller will stop the heat pump unit. The reason for this failure is the open circuit, short circuit or quality problem of the temperature sensing probe. For example, the change of resistance value cannot reflect the water temperature correctly because the temp sensor gets wet. In such case, the open circuit or short circuit failure should be handled or replaced before restart.
This is similar to the water temperature sensor failure protection. It is also necessary for air source heat pump to know the temperature signal of the evaporator before it starts to work, the purpose of which is to determine whether the system needs to defrost and stops the fan operation in order to prevent the compressor exhaust temperature from getting too high. If the ASHP cannot detect the signal, it will also shut itself down to protect the unit.
