Get to know the piping system of the fan coil unit

One of the most practical air conditioning equipment in buildings are fan coils, which produce cold or hot air by using the flow of cold water from the chiller or hot water from the boiler of the engine room of the building (or package) in copper coils (pipes) and by means of a fan. Some fan coils have a two-tube system and some have a four-tube coil. If the fan coil system is designed to work with cold and hot water generating devices such as chillers and boilers (units outside the building), it must have a coil for cold and hot water, and if it is combined with pump systems Thermal designed like VRF and GHP (units outside the building), it must also have a copper coil for the refrigerant. In fact, the coil of each fan coil in such devices is considered the evaporator of the condensation refrigeration cycle, in such a way that the refrigerant, by flowing into the coil and exchanging heat with the air around the coil, causes the air temperature to decrease or increase.

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Fan coil piping system

The structure of the two-pipe system in the fan coil

If the fan coil system is two-pipe, one pipe is for hot or cold water and one pipe is for hot or cold water return, so in the two-pipe type, either only cold water flows in the fan coil or only water. hot and if one unit needs cold air and another unit needs hot air at the same time, the fan coil with a two-pipe system will not meet both needs at the same time. A two-pipe fan coil requires a status change sensor, which is usually a temperature sensor and is installed on the water inlet to the system to determine how the system is operating (heating or cooling).
In the case of using a two-pipe fan coil, the building uses a central chiller or an independent mini chiller to cool the water in the summer season, and a hot water boiler or an independent package to heat the water in the winter season. Due to having an inlet pipe and a water return pipe, it is possible to pass only one type of fluid (either cold water or hot water) in the building's cooling or heating piping system. In this case, the two-pipe fan coil starts working according to the seasonal weather conditions in the building and provides only heating or cooling in each season, and it is not possible to use the cooling and heating capabilities at the same time. Therefore, the residents of the building may have to endure some temperature fluctuations every year in the spring and autumn seasons.
Also, the fan used in the two-pipe fan coil has three speeds; Low speed, medium speed, and high speed, which this speed is set with the purpose of transferring different amounts of airflow in terms of CFM (ventilation volume of the fan coil in cubic meters per minute).

Four-pipe system in fan coil

But if the fan coil system has four pipes, one outgoing copper pipe and one return copper pipe for the hot water coil and one outgoing copper pipe and one return copper pipe for the cold water coil are allocated, in this case, the system can be used simultaneously. Heating and cooling were used.
For example, if in the autumn season, a part of the building that faces the sun needs cooling and another part of the building that faces the sun needs heating, they can have the possibility to simultaneously in the desired parts. The building should use both cooling and heating. The four-pipe system of fan coils has a higher price, but it also has more advantages than the two-pipe type. The four-pipe fan coil is designed in such a way that due to the possibility of providing simultaneous cooling and heating of air in different environments of the building, it is also able to dehumidify the air. However, the dehumidification rate may be limited due to the increased temperature of the incoming cold water.
The function of the thermostat in the four-pipe fan coil is that the thermostat opens the water control valve to the heating or cooling coil and turns on the ventilation fan so that the airflow circulates on the heating or cooling coil. So, in this way, the four-pipe fan coil will start its heating or cooling function at any moment of the day, month, or year based on the set temperature of the thermostat.

Another important point that we should mention in the field of fan coil piping is the calculation of the diameter of the hot and cold water pipes entering the coil of each fan coil. If a fan coil with the appropriate type and even capacity is selected and installed for each space, but the diameter of the hot and cold water pipe entering the coil is insufficient and small, the said fan coil will not be able to provide the required heating or cooling of the respective space. Was. The calculation of the diameter of fan coil piping should be done exactly according to the engineering diagrams of the facilities and only by experts and engineers of the project facilities.

You can also read the article LOW CONSUMPTION AIR CONDITIONER AND DUCTED SPLIT for more information.

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Final word

In this article, we learned about the fan coil piping system. We hope that we have provided useful information. The specialized collection of DamaTajhiz (the first and most reliable specialized collection in the field of building facilities equipment and all air conditioning devices since 2013 and has 3 valid business licenses) offers all products with the guarantee of the originality of the goods, valid warranty and reasonable price to all our dear customers. Gives. To get more information about the selection of fan coils needed for the project, you can contact the experts of the air conditioning equipment department of DamaTajhiz during office hours by phone number +9821-88822550.

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