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The Difference Between a Fan Coil and Evaporator Coil

by Megan Althoff | Oct 10, 2017 | HVAC, Rooftop Unit, HVAC Maintenance | 0 Comments

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The fan coils and evaporator coils are essential for the successful operation of your air conditioning unit. When these two coil systems are operating efficiency, the heat and humidity is removed from your Chicago building and vented to the outside. When the coils are not operating efficiently, you may notice that your HVAC system isn’t reaching the desired indoor temperature and/or that your vents are blowing warm air or air that isn’t as cool.

Fan Coil Units VS. Evaporator Coils

Fan coils and evaporator coils both transport coolant through your system. In a split system, the fan coil unit, also known as the condenser coil, is located outside while the evaporator coils are located inside. In a commercial rooftop unit, the fan and evaporator coils are located within the same unit.

Evaporator Coil

The evaporator coils are responsible for removing heat from the inside of your building. They are often located inside the air handler unit. The air handler unit blows the hot indoor air across the cooler coils. The liquid refrigerant absorbs the heat, which turns the refrigerant into a gas. The refrigerant then flows into the fan or condenser coil where the excess heat is vented.

Common Problems with Evaporator Coils

  • Frozen coils
  • Excess moisture
  • Accumulation of dirt and dust on the coils

If your evaporator coils do not have enough refrigerant passing through them due to a leak in the system or your blower fan isn’t operating correctly, the coils could freeze. This causes inefficient cooling and can lead to the unit ceasing to operate.

In addition to providing cooling, the evaporator coils also remove humidity. That humidity collects as water onto the coils. Under normal circumstances, that water is drained. When the water isn’t properly drained, it can lead to a sudden buildup of dirt, dust and bacteria. In severe cases, you could even end up with mold inside your system. When dirt and dust collect on the coils, they are not able to properly transfer heat, which can lead to a reduction of system efficiency.

Fan Coil

The fan coil is also known as the condenser coil. As the hot refrigerant flows into the condenser, the fan blows outdoor air onto the coils. This helps to cool the coils and returns the refrigerant to a liquid state so that it can absorb more heat. Once the refrigerant has sufficiently cooled, it is transported back to the evaporator coil unit.

Common Problems with Fan Coils

  • Dirt and dust Accumulating inside and on the evaporator coil unit
  • Broken or bent fan blades
  • Refrigerant leaks due to corrosion

Problems with the fan coil can lead to reduced heat transfer. This can result in warm air blowing from your vents and higher than normal indoor temperatures. Your AC unit may also work longer and harder to cool the inside of your building, which can greatly reduce your units life expectancy and lead to more broken parts.

Maintaining Fan Coils and Evaporator Coils with Althoff

Our HVAC technicians can help you maintain the integrity and efficiency of your HVAC system with regular preventative maintenance, which includes cleaning the interior and exterior of your HVAC system. We also check for refrigerant leaks and examine all moving parts, including motors and fan blades in order to ensure that they are in proper working condition. If our technicians notice any problems, they will explain the problems to you and recommend the appropriate repairs.

To schedule an AC preventative maintenance service that includes cleaning your fan coils and evaporator coils, call us at 800-225-2443.

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