Fancoils are devices that are part of an air conditioning and heating system. They are a tubular-plate heat exchanger along which a heat carrier moves, blown by a fan from the back side. In appearance, they are similar to the internal block of a split system. But the heat exchanger is installed inside, and not the evaporator, although the principle of operation of the systems is the same.
Fan coil units themselves are not a separate element of climate technology. This is the indoor unit of the air conditioning system, in which the main role is played by chillers. Both blocks are connected by piping, along which water (cold or hot) moves.
Fan coil binding units
There are no binding schemes regulated by standards or rules. Each scheme is selected in accordance with the requirements of the customer, taking into account the location of the fan coils, their number and capacity of the walker installation. Depending on the tasks, the schemes are divided into two-pipe and four-pipe.
Only one type of coolant moves through the two-pipe system: cold water in the summer, hot in the winter. In this case, the transition is made by connecting fan coil units to one of the systems. For example, if the devices are switched to winter operation, water is drained from them, which circulates from the heat exchanger of the chiller. It is connected to the heating system, which is then filled with water. When switching to summer mode, the opposite is true. If the chiller comes with a heat pump, heating through the fan coil can be arranged without switching to a separate system.
In a four-pipe system, two pipes are connected to the fan coil at once: one from the chiller, the other from the heating system. Switching is performed by a three-way valve.
A distinctive feature of such an air conditioning system is that one chiller is used to cool the water, which connects to several fan coil units located in different rooms at once. At the same time, the temperature of the outgoing air can be controlled in each device individually, independently of the others. For this, remote control panels are used.
Classic design
Tying a fan coil with a two-way valve is a classic circuit. In fact, this is the supply pipe and return pipe. Water as a coolant will pass through the device, giving off cold or heat, returning in a closed circuit to the chiller or boiler. The scheme is simple and convenient to maintain, but not effective if the task is to adjust the temperature and pressure of water inside the heat exchanger.
Increasingly, manufacturers are offering a fan coil unit with a three-way valve. It is considered more technological. In front of the fan coil, a pipe parallel to its connection is installed, where the valve crashes. The temperature and pressure of the water in the system are controlled respectively by a thermometer and a pressure gauge mounted on the supply pipe in front of the fan coil. In addition, the three-way valve acts as a coolant shutoff if the system is completely shut off. Without a valve, water will still flow into the fan coil, albeit in smaller quantities with reduced intensity.
Both fan coil units can be in vertical or horizontal design. At the same time, two connection options are offered: left or right.
Rules for connecting fan coils
Regardless of what type of fan coil is installed in the room (floor, wall or ceiling), it is necessary to choose the right mixing unit for it.This mainly depends on the power of the installed device and the diameter of the wiring pipes for the coolant.
There are no special requirements for the mixing unit itself for fan coils. The main thing is the tightness of the joints and a complete set of shutoff valves. The unit is connected to the device through flexible metal hoses, which simplifies the installation process to a minimum. Manufacturers offer a fairly wide range of mixing units, which have the ability to interchange their individual elements.
Requirements for the installation of the mixing unit:
- installation is carried out on separate brackets so that there is no pressure from the device on the fan coil;
- installation under a suspended ceiling structure requires a hatch on the ceiling to provide free access for maintenance, repair and replacement;
- the installation is carried out in such a way as to ensure free air removal from the air conditioning system;
- the diameter of the pipes used in the mixing unit should be equal to or slightly larger than the diameter of the fan coil fitting;
- the supply piping must be insulated so that the loss of heat or cold does not increase.
The fan coil unit with a 3-way valve or 2-way does not include a condensate drainage system (drainage), but it must be installed.
During the operation of the fan coil in cooling mode, condensate will form on the surface of the tubes and plates of the heat exchanger, which flows into a tray specially installed under the heat exchanger. In the lateral part of the latter there is an outlet pipe through which the condensate is drained.
The drainage system itself is self-flowing, so the pipe connected to the tray should be laid with a slight slope of at least 1 °. The connection of the pipe and the drain pipe is usually done with a clamp. Before starting work, the drainage is checked by pouring a small amount of water into the tray. If the fluid does not go away, it means that the slope is incorrectly set. It needs to be fixed.
Since this type of air conditioning system is connected with a coolant, the main requirement for its installation is crimping after completion of all work. It is carried out in different ways, but more often water is supplied to the pipe wiring under pressure, thereby checking smudges at the joints.
Useful Tips
Since there are only two tying schemes: with 2 or 3-way valves, it is worth considering the positions associated with their correct application. For example, if a fan coil is installed on a heating system, it is not necessary to install a unit with a three-way valve.
- You can adjust the heat transfer power of devices by simply turning the fan off or on.
- You can adjust the balancing valve, which is installed on the return circuit.
- On a 4-pipe connection system, it is better to use two-way valves. If you put three-way, the volume of the coolant in the return circuit increases.
- If the heating system is powered by a chiller heat pump, it is best to install a mixing unit with a three-way valve.
