What You Need To Know About Chilled Water Coils and Evaporator Coils

Coils form the basic working blocks for heating and cooling systems including air conditioners, refrigerators, fans, etc.

What You Need To Know about Chilled Water Coils

The following tips will help you:

  • Chilled water coils usually come three to twelve rows deep. Hot water coils on the other hand, come with one or two rows.
  • Most chilled water coils are manufactured with ½” OD tubes and sometimes, 5/8”OD tubes. The choice falls within the discretion of the manufacturer in terms of cost of production. They can also be used as substitutes for each other.
  • ½” tubes usually have a centre to centre distance of 1.25”. The ones that are 5/8” have a centre to centre distance of 1.5”. This means that for a chilled water coil that has a fin height of 30”, the number of tubes per row will be determined by 1.2”(24), or 5/8”(20) tubes per row.
  • The quality of a chilled water coil is hugely determined by the thickness of the tube. A thicker tube wall helps the coil to last longer.
  • A major determinant of the overall quality of a chilled water coil is the quality of the fins. Fins are primarily not designed to act as filters but they do! To cut costs in making coils, it is possible to make 14 fins/inch with a lesser number of rows instead of making 8 10 fins per inch. It is important to note that the deeper a coil is, the more difficult it will be to clean.
  • Fins have the capacity to carry out maximum transfer of heat. They usually have corrugations in the fins and have ripped edges. They also have staggered tubes in every row and extended fin collars. All of these help in the process of heat transfer.
  • Aluminium fins are more economical in terms of cost for heat transfer when compared to copper coils.
  • 304 stainless steel is used to manufacture the casings of most chilled water coils. Such casings usually last longer, are stronger, and are stackable as well. They are also not very expensive.
  • Circuiting is one thing that mist be considered in the manufacturing of coils. Proper circuiting determines how efficient and effective the coil will be. 

What You Need To Know About Evaporator Coils

Evaporator coils have the primary function of removing internal heat. Common features of evaporator coils include:

  • They are located inside the cooling unit.
  • They can be made of aluminium or copper. They can also be coated with special coatings like epoxy paints to help them resist corrosion.
  • When the unit distributes hot air sucked from inside a room across the evaporator coils, the refrigerant is turned into gas from its liquid form when it absorbs this heat. The evaporator coils work with the condenser coils in venting this heat and produces the cooling effect.
  • Evaporator coils can get frozen. This occurs when there is not enough refrigerant flowing them either because there is a leak or because the fan is not blowing properly. This leads to poor cooling and may even spoil the unit entirely.
  • Evaporator coils remove humidity.
  • Dust, leaves, and other debris can accumulate in them and this needs proper cleaning in order not to block the vents and allow for maximum cooling.
  • Evaporator coils can become contaminated when the moisture content that it usually has, provides a fertile breeding ground for different organisms including mold. This will require proper cleaning and the use of disinfectants in order not to cause diseases when the air is inhaled. 


In the purchase of both cooling and heating units, it is important to study the buyer guides to see the specifications and types of the coils and other accessories as well as the performance standards and ratings.



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