Fan coil unit
A fan coil unit is an air conditioning unit for air treatment that consists of a heat exchanger and a fan . It is part of a decentralized air conditioning system and is used in residential, office and industrial buildings as well as on ships to change the room climate . The fan coil unit influences the air temperature and the relative humidity and is either controlled manually or regulated by a thermostat .
The English term for fan coil is fan coil unit [ FDs kɔɪl ju: nɪt ] ( German fan spiral tube device ).
Assemblies
Fan convectors consist of the two assemblies heat exchanger and motor fan. The fan is driven by an electric motor that requires a power supply and has speed control . A replaceable air filter can be connected upstream to clean the air and reduce abrasion on the fan blades . A basic construction takes on the assemblies and their loads. Depending on the design, the basic construction can be supplemented by a housing, a condensate pan, a mixed air box, sound and thermal insulation, an electric heater and grille on the air intake and exhaust openings.
function
A heat transfer medium flows through the fan coil and leads via a heat exchanger by convection of the circulating air thermal energy to or removes it. The fan coil unit receives hot water from a heat generator ( boiler , heat pump ) and cold water from a central chiller . In contrast to radiators and classic plate heating, fan convectors can not only heat, but also cool and, when connected to a primary air network, also ventilate.
The heating and cooling capacity of a fan coil unit is influenced by the following parameters:
- Water flow rate [l / h]
- Pressure drop on the water side [kPa]
- Air volume flow [m³ / h]
- Motor power [W]
- Current consumption [A]
The fan generates an air during the compression of the sound pressure , which can be perceived by the direct mounting position with the user as noise.
care
The heat transfer medium is usually conditioned in a central operating room. The technical equipment required to extract thermal energy from the cold water circuit via refrigeration machines or to dissipate it to the outside air via cooling towers is housed in the operating room . The two to four supply and discharge lines are made of thermoplastic (ABS) , steel or copper . In order to prevent the formation of condensation and to reduce the loss of cold , the cold water pipes are sheathed with insulating materials made of foamed polyvinyl chloride or acrylonitrile butadiene.
Types
Depending on the number of lines, fan coil units can be divided into two types, the two-line and the four-line. Convectors with two lines have an inlet and a return line. The supply line can carry both hot and cold water, depending on the season or the outside temperatures.
Convectors with four lines have two inlet and two return lines and hot and cold water can flow through them at the same time. Since buildings often have areas with partial internal heat generation (e.g. in technical rooms) and heat losses (e.g. in the gate area), simultaneous cooling and heating of building areas is not uncommon, which is why 4-pipe systems have become established.
The cooling register cools the air flowing through and dehumidifies it depending on the selected cold water temperature and the relative humidity . During this process, water vapor can condense, which has to be collected and discharged to the environment or the sewage network. For this purpose, the fan coil unit has a condensate collecting tray with a drainage channel.
regulation
The heating and cooling output delivered by the device can either be regulated on the water or air side. With the water-side control, the water flow flowing through the heat exchanger is controlled by valves. With the air-side control, either the speed of the fan or the bypass ratio of the secondary air flow is influenced.
Flap control
With the flap control, lamellas either guide the air flow through the registers or guide the secondary air through a bypass, bypassing the heat exchanger.
Fan control
The amount of heat or cold to be emitted is regulated by regulating the speed of the fan motors. Some manufacturers implement speed control by step switching the AC transformer, which supplies the fan motors with electrical energy. Usually the speed controller is integrated in a room thermostat and is controlled manually or automatically by a digital room thermostat. Fan motors typically have either an AC shaded pole motor or a motor with a running capacitor. More modern developments rely on electronically controlled, brushless DC motors.
thermostat
The thermostat can either be installed in the device or outside via a cable connection. In many modern buildings, the control is regulated by a central room or building automation system, which controls the speed of the fans and thus the air volume flow via digital field devices depending on temperature sensors . Building management systems can be used for fan control and temperature control.
Application area
Fan convectors are preferably used in areas where people do not stay permanently, such as storage rooms, corridors and technical rooms. Due to the simple technical construction are fan coils in procurement often cheaper than through ventilation ducts run air conditioning systems with central ventilation unit ( english air handling unit ). In high-rise buildings, fan convectors are also used stacked, mounted one above the other from floor to floor and connected via a cable network.
Assembly
Fan convectors carry out the air treatment types conveying, filtering and temperature control directly in the room and can be installed both exposed and built behind. Exposed fan coil units can have different installation positions: wall-mounted, ceiling-mounted or free-standing. Typically, free-standing fan convectors are enclosed for optical and protective reasons and have a ventilation grille for the incoming air and a diffuser for the even distribution of the outgoing air.
A concealed fan coil unit is typically accessible in the false ceiling or in a shaft. The ventilation grilles and the diffuser are installed flush in the false ceiling and the supply air is routed to the fan coil unit via ventilation ducts. The return air is mostly not routed through ducts, but rather through the ceiling space. In residential buildings, the fan coil units require a square opening through the concrete ceiling due to the lack of a false ceiling.
Compact air conditioner
Compact air conditioning units ( English Unit fan ) are fan coil units with supply air . They only need an electrical supply and are mounted directly on or in an outside wall. They suck in outside air through a wall opening and discharge condensate. In addition to air conditioning, these devices can also ventilate rooms . They are preferably used in classrooms, hotel rooms, apartments and condominiums.
Regulations
The guideline VDI 6022 of the Association of German Engineers regulates the "hygiene requirements for ventilation and air conditioning systems and devices". VDI 6022 requires regular inspections, maintenance and possibly cleaning work in order to ensure a perfect operating condition. The trade supervisory authorities and the offices for occupational safety are responsible for monitoring compliance with VDI 6022. The EN 13779 describes the "Ventilation for non-residential buildings" and DIN 1946-6 the "ventilation of residential buildings".
literature
- Recknagel, Sprenger, Schramek: Pocket book for heating + air conditioning . 76th edition, Deutscher Industrieverlag, 2012, ISBN 978-3-8356-3301-8 .
Web links
- Directive 2008/50 / EC (PDF) ofthe European Parliament and of the Council of May 21, 2008 on ambient air quality and cleaner air for Europe
Individual evidence
- ↑ a b c d e Rainer Sökeland: Fan coil control in practice. (PDF; 93 kB) (No longer available online.) In: DE-Jahrbuch Gebäudetechnik 2007. 2007, archived from the original on January 24, 2013 ; Retrieved February 25, 2015 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b c Air conditioning systems according to use and ventilation function. In: BauNetz Wissen • Building technology. Retrieved February 25, 2015 .
- ↑ Hygiene requirements for air conditioning systems and devices • VDI 6022. In: bosy-online.de. Retrieved February 25, 2015 .
