A condenser is the big box part of your central air conditioning system that sits outside your home.
Central air conditioning systems have essentially two parts:
- An evaporator that removes unwanted heat from the air and transfers it to a refrigerant
- A condenser that removes unwanted heat from the refrigerant and transfers that heat outdoors
Condensers are heat exchangers that induce condensation on the pressurized refrigerant to change the phase from a gas to a liquid. The primary component of a condenser is the condenser coil, through which the refrigerant flows.
Types of condensers
There are three types of condensers. These types differ in how they remove excess heat:
- Air-cooled condensers remove heat by blowing air over the condenser coil. This is the most common type of condenser in residential systems.
- Water-cooled condensers remove heat by pouring water over the condenser coil.
- Evaporative condensers do not typically use refrigerant. They remove heat by allowing water to evaporate directly into the air.
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Both split air conditioner and heat pump condensers have the same basic parts. The condenser cabinet contains the condenser coil, a compressor, a fan, and various controls.
Condenser coils can be made of copper tubing with aluminum fins or all-aluminum tubing so heat can rapidly transfer. You should keep it as clean as possible to maintain its heat-transferring efficiency.
The condenser fan is a vital part that circulates air across the coil to facilitate heat transfer. The efficiency will be impacted or the compressor could fail if the airflow is blocked. The area around the compressor’s coil and fan must be free of dirt so that maximum airflow can occur.
The compressor is the heart of the system since it compresses the refrigerant and pumps it to a coil in the form of a hot gas. In air conditioners, this is cooled at the condenser into a warm liquid and passes through a pipe into the evaporator coil, where it expands and cools. In heat pumps, the hot gas is pumped directly to the evaporator coil to provide heat.
Air conditioner condensers
Condensers used only in air conditioning do not have many controls. A contactor switches the power on and off. Capacitors start and run the motors.
Some optional controls like brownout time delay, hard start kit, crankcase heater, and low ambiance control are available. Brownout time delay protects the compressor, shutting the contactor off when voltage drops and too much current is pulled in by the motors.
Heat pump condensers
These have controls that are more complex than those of an air conditioner. In addition to the contactor, capacitor, and other optional controls, there is also a reversing valve, defrost timer, and adjustable temperature sensor.
The reversing valve directs the flow of compressed gas to the condenser coil for air conditioning or to the evaporator coil for heating.
The condenser coil extracts heat from the air outside the home. When it does this, it becomes very cold and frost collects on it. An excess of frost restricts airflow, reducing the coil’s effectiveness.
The defrost control automatically switches to the air conditioning mode even without the condenser fan running. This makes the ice melt when the hot gas runs through the coil, after which the system switches back to heating mode.
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