Here would like to share with you how to select the right fan coil unit and how to install a fan coil?

What is a fan coil unit? A fan coil is a relatively small piece of equipment consisting of a fan, a coil, and other components used to provide cooling or heating to the air in a room. These units are quite common in residential and commercial applications.

Indicators of fan coil testing include air volume, cooling capacity, heat supply, unit fan power cooling capacity, water resistance, acoustic level noise, condensation, condensate treatment, motor winding temperature rise, thermal insulation resistance, leakage current, and grounding resistance.

However, we also evaluate the fan coil quality standards based on its air volume, cooling capacity, noise, and power consumption. In terms of power consumption, the difference between the maximum power consumption and the minimum power consumption of the same product is approximately 20W or more.

Now we will discuss fan coil selection, matters to note, and the impact of parameter changes on performance and installation techniques.


How to select the right fan coil unit



  • A guide to choosing the right type of fan coil

In general, the two main characteristics of fan coils are cooling (heat) and air delivery.

  1. According to the selection of room circulation air volume: room area, floor height (after the ceiling), and room ventilation times the product of these three is the number of cubic feet of room circulation air volume. You can determine the fan coil model using the circulating air volume corresponding to the high and medium-speed air volume of the fan coils.
  2. Based on the room cooling load calculation: based on the unit area load and room area, a value of room cooling load corresponding to the cooling capacity of the fan coil can be determined.




  •  How to select a fan coil

1. Cooling capacity

Insufficient cooling capacity is currently one of the most user complaints.

A major reason for this issue is that many enterprises do not have their own testing equipment, the parameter values on the sample are also copied from other manufacturers, and their own production of the coil is not thermally efficient (mainly caused by the form of fins, expansion tube quality, production process, etc. When conducting project visits, it is important to pay attention to the testing facilities and methods used by the manufacturer.

It is difficult to imagine how a manufacturer can produce good products without its own testing equipment.




2. Air volume

Considering the air volume of the coil is a challenge.

In China, most manufacturers only provide three-row coils, but there are also manufacturers who provide two-row coils.

In fact, the choice of two-row coils is more appropriate for most civil building air conditioning systems (with the exception of high humidity conditions).

As a result, two-row products have a larger air volume at the same cooling capacity, which will increase the number of air changes in the room and improve accuracy and comfort. With the same cooling capacity, a small temperature difference and large air volume will achieve better air conditioning results than a large temperature difference and small air volume.


3. External residual pressure

In the current national standards, fan coil air volume, cooling capacity, noise, and other parameters of the test are measured outside of the static pressure of zero conditions.

The actual use of the coil outlet in front of the air duct and often to receive a small section of the wind louvers. Some projects also have return air boxes, so it may find the actual air volume of the coil to be lower than its nominal air volume. The result will be a reduction in room air volume, an increase in temperature differences, and a reduction in the comfort of the air conditioning system.
Some designers avoid such a situation in the selection of the mid-range air volume of the coil to avoid insufficient air volume but increase the initial investment in the project.

As a result, it is recommended that in the case of domestic testing standards that have not yet changed, the selection of coils gives precedence to the unit with residual pressure (normally 10-15Pa).




4. Noise

The gap between domestic and foreign products is wide in this area, and there are complaints about the quality of the coils.

The coil motor and fan configuration and matching are unreasonable, the manufacturer’s quality management is not strict, and assembly workers do not have a strong sense of responsibility, resulting in unstable product quality.

The coil motor and fan configuration and matching are unreasonable, the manufacturer’s quality management is not strict, and assembly workers do not have a strong sense of responsibility, resulting in unstable product quality.


  •  Parameter changes and performance

1. when the water supply temperature changes, the cooling capacity changes when the water supply changes. According to some fan coil product performance statistics, when the water supply temperature is 7 degrees the water supply is reduced by 80%, and the cooling capacity is reduced by 92% or so, indicating that when the water supply changes the impact on the cooling capacity is relatively small.

2. As the temperature of fan coil water supply and return water increases, cooling capacity decreases as well.
According to statistics, when the water supply temperature increases by 1 degree, the cooling capacity drops by 10%. The higher the water supply temperature, the greater the reduction, and the dehumidification capacity decreases.

3. Changes in water supply conditions, fan coil air volume, cooling capacity, and air conditioning treatment enthalpy.
In general, the cooling capacity decreases, the enthalpy difference increases, and the power consumption per unit cooling capacity level does not change much.

4. The temperature of the water entering and leaving the fan coils increases, the volume of water decreases, and the thermal coefficient of the heat exchanger coil decreases as well.

In addition, the heat transfer temperature difference also changed. Therefore, the cooling capacity of the fan coil decreases with the increase in the water supply temperature.

According to statistics, when the water supply temperature is 7 degrees, the supply and return water temperature increases from 5 degrees to 7 degrees, and the cooling capacity is reduced by 17%.





  • How to install a fan coiler

1. Install the brightly installed vertical unit with the energized side slightly higher than the water side to facilitate the discharge of condensate.

2. Install the condensate pipe of the unit at a certain slope (generally 5 degrees), which will facilitate the discharge of condensate.

3. The pipes of the water inlet and outlet should be insulated to avoid condensation during summer use.

4. The condensate pan drainage hose of the unit shall not be flattened and bent to ensure the smooth discharge of condensate.

5. Heat exchanger fins and elbows should be protected in the installation, and they should not be collapsed or touched by leaks.

6. When installing the horizontal unit, the boom and expansion bolt should be reasonably selected.

7. The inlet and outlet water pipes of the horizontal brightly installed unit can be first connected out of the machine on the ground, and then connected to the pipeline after lifting, or the panel and condensate tray can be taken off and connected after lifting, and then the water pipes can be insulated to prevent condensation.

8. The inlet and outlet water piping of the vertical open unit can be installed without removing an air outlet panel, and the water piping is insulated to prevent condensation.

9. Air should be released through a manual valve in the return pipe before the unit starts up and closed once it has finished exhausting the air in the coil and pipeline.

10. Prepare grounding bolts on the shell of the unit for connection with the protection grounding system during installation.

11. Power supply voltage is (220*220×10%) V, 50Hz, and the line connection is made in accordance with the “electrical connection line diagram” provided by the manufacturer, and the color of the connection wires must match the label on the unit.

12. Since the size of the air coil air conditioner produced by each manufacturer is different, the return air grille and air outlet should be manufactured carefully to avoid mistakes.

13. Temperature controllers should have a switch that switches between summer and winter settings when used in summer and between winter and summer when used in winter.

14. It is important that the insulation material of the unit is not damaged during installation, and if it happens to be dislodged, it needs to be glued firmly again, and the connection to the air supply duct and outlet needs to be made tightly at the same time.




If you have any other technical questions about the fan coil, kindly contact us.