6 Reasons for Air Source Heat Pump Air Conditioner Not Heating in Winter

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Update time : 2015-03-11 21:17:08

Environmental Factors

When air source heat pump (ASHP) air conditioner is heating at low ambient temperature, the energy efficiency ratio is reduced. The heating effect is not ideal in cold winter, which is a normal phenomenon. For the heat pump type air conditioner without automatic defrosting, the min ambient temperature is 5℃. If it is lower than this temperature, the heat will not be produced or the heating effect will be very poor. This is because the frost on the external heat exchanger blocks the air flow and can no longer absorb heat from the outside. For ASHP air conditioner with automatic defrosting, the min ambient temperature is also -5℃. With ambient temperature lower than this, the heat pump unit would not produce heat effectively.


Improper Use

If the filter screen is not cleaned in time and the air circulation is blocked inside after the heat pump ac has been used for a long time, the heating effect will be affected to a certain extent. f the dust on evaporator and condenser is too thick, the heat exchanging effect will be reduced, resulting in the decrease of heating capacity and the increase of power consumption. The set heating temperature is too low, which also affects the heating efficiency.


Such conditions like doors/walls not well insulated, or windows/doors opened too frequently, will cause indoor heat loss unintentionally and resulting in insufficient heating.


Air Flow through the Valve

The heat pump air conditioner uses a four-way valve to switch between heating and cooling. If the four-way valve is connected with air, some refrigerant that should be involved in heat exchange will be directly returned to the air return pipe from the outlet pipe of the compressor at the four-way valve, resulting in the decrease of refrigerant involved in heat exchange and the decrease of heat exchange efficiency, causing the shortage of heating capacity. 


Insufficient Refrigerant

If the refrigerant leaks or is insufficient, simple self-tests can be carried out to identify whether there is fluorine leakage.


Failure of Defrosting Controller

The evaporator of heat pump ac is located in the outdoor unit. For those with the heat defrosting device, if the defrosting controller fails, which makes the ac unable to turn into the defrosting operation state in time, the frosting phenomenon of the evaporator will occur during its heating state, which will affect the heat exchange efficiency, resulting in insufficient heat generation and even shutdown.


At this time, the following situations shall be observed: the defrosting temperature sensing device is misplaced; the contact is stuck or in poor contact; the fan impeller slips or the air duct is blocked; and the electron magnetic valve or start relay fails.


Failure of the Auxiliary Electric Heating Function

At present, PTC electric auxiliary heating technology is widely used in air source heat pump for heating and cooling. The technology can produce heat rapidly under ultra-low temperature conditions, with high efficiency, safety and reliability, and can be used for a long time. If the electric backup heater circuit or equipment fails to work normally, it will lead to the lack of heating capacity when the ambient temperature is relatively low, or even stop heating completely when the environment is bad.


If the heating is normal when the ambient temperature is high (above 5℃), but the heating is insufficient when the ambient temperature is low (below 0℃), it should be suspected that the electric backup heater circuit or equipment is in fault, and the two parts should be inspected during maintenance.

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