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LS/LR air handling units

LS/LR units


Basic features and advantages

LS/LR air handling units are built in double skin construction, with 50mm thick rock wool insulated panels, within the capacity range of 1.000 – 100.000 m3/h. Outer surfaces of the units are made in dependance on application or demand.

Selection of most suitable filters for the application and the unit are properly made. Dampers used in the air handling units and cabinet fans are made of aluminum profiles and aluminum damper blades with plastic driving gears. In accordance with energy efficiency regulations, plate type, rotary type or run-around-coil type heat recovery units are employed.

To meet the required air flow and static pressure requirements, plug fans with bacward curved blades are selected. Electric motors are of IP55 class and are CE approved.

Heaters, colers, direct evaporators are made from cooper and alumnium or based on reqest only from cooper, stainless steel, with coating…



Usage and working conditions

Frameless air conditioning units of the series LS/LR are modular units of the square and rectangular cross section. The units are designed for central distribution and air conditioning, i.e. filtering, war­ming, cooling, recuperation, humidification and dehumidification in factory premises, administrative buildings, hospitals, shopping centres, schools, sports areas, restaurants, food businesses and other premises. The units in standard design are placed in normal environment with the ambient temperature from -30 °C till + 40 °C. The units are produced in modifications for indoor / outdo­or / hygienically / seismic resistant design and for environments with ATEX explosion risk.


AHU selection program

By using the selection program, the most economic unit meeting the required conditions, can be easily selected. This program has been prepared using the technical data and the selection programs of the components used within the AHU. Through the user friendly interface of the program, selection and dimensioning of the unit can easily be made and the technical outputs can be obtained.


Detailed description

Casing Construction

Sections are produced from frameless sandwich panels. To ensure air tightness, EPDM type gaskets are used between panels and sections. The frameless construction provides a completely pure interior in the whole length of the section (the unit), thus creating an automatically hygienic design (without brims).


The covering of the panel is represented by two metal sheets of the thickness 0.8 mm. The metal sheets are zinc-coated (275 g/m2), painted (in RAL colour pallete) or stainless (AISI 316), in different combinations on the outer as well as inner side. Inside the panels there is an insulation filling from mineral wool with the mass density of 50 kg/ m3, the flammability degree A1 (EN 13501-1). The thickness of the panel is 50 mm.


Double skin service doors are installed on filter, fan, humidifier and empty sections, to enable access and servicing. Lockable access doors are used on all fan sections. Air tightness is provided by special gaskets. Optionally, doors may be equipped with inspection window and lighting inside the section.


Dampers are made of airfoil shaped aluminum blades housed in an aluminum casing in an opposed blade configuration. Gaskets are placed on the edges of the damper blades to ensure air tightness. Plastic gears that operate the damper blades are placed within the damper casing, outside of the air stream. Dampers can be manual or motor operated. Optionally, servomotors, flexible connections and rain hoods are available.


The total cross section of LS/LR air handling units are used as filtering area to reach maximal efficiecy by keeping compact size of unit. Filters cartridges has standardized dimensions and are fixed in their own casings. Filter can be easily install and dismantle. Plate filters, bag filters, metal filters, active carbon filters, compact filters and HEPA filters are available.

Plate type heat recovery system

The plate type heat exchangers used in this system consist of a number of specially shaped, highly conductive aluminum plates, arranged in a cross flow shape and enable transfer of heat between exhaust air and return air, without mixing the two air streams with each other. This system can operate between -20°C and 80°C temperatures. Lower temperature can be allowed but it must be discused with producer. To prevent freezing at low temperatures, systems with a bypass damper, can be used. Mixing flap can be installed too. On the exhaust side is stainless steel drain pan is installed. If air velocity higher than 2,5m/s drop eliminator is installed too.  Water collected in the drain pan is discharged through the drain pipe.

  • Efficiency is up to 70%
  • No electric connection is necessary
  • Long life
  • Low operating cost

Rotary type heat recovery system

Rotor is made of specially shaped aluminum sheets and is driven by an electric motor through a belt drive.

In general, they can be classified in three groups:

  • Condensation rotors; is the economic solution used in ordinary air conditioning applications. These rotors condense and thus remove the excess humidity in the air.
  • Hygroscopic rotors; are used to transfer humidity from one air stream to the other, within certain temperature limits, in comfort air conditioning applications. Surfaces of the rotor have the characteristic of absorbing humidity.
  • Sorption rotors; can transfer high amounts of humidity from one air stream to the other, through the desiccant coated material of the rotor. They are most effective in high temperature and high humidity conditions. Through their ability of pre-cooling and de-humidification, they tend to decrease the total cooling requirement of the system, resulting in application of a smaller size chiller.

High pressure applications, abrasive atmospheres, marine applications, etc., must be consult with producer. Heat transfer efficiency of the rotors can be controlled by rotation speed . Efficieny control requirement must be clearly specified while ordering. Maximum quantity of mixed air in rotor is around 5% of total air flow (depend on conditions). Properly configured and pressurized rotors equipped with a sweeping zone has  quantity of mixed air in below 1% of tolal air flow. Angle of the sweeping zone is optimezed to reach best ration between heat recovery efficiancy and air mixing.

  • Efficiencies vary between 65% and 85%
  • Electric connection is required. Capacity can be adjusted through variable speed controlled motor
  • Compact construction; occupies minimum amount of space
  • No risk of freezing
  • Capable of transferring humidity (and sorption)

Run-around-coil type heat recovery systems

These are low efficiency systems with the heat transfer is from air to water and from water to air. Water circulating in a closed loop is used to transfer the heat between the exhaust air and the fresh air streams. There is a circulating pump and a balancing tank in the system. Stainless steel drain pan is used on the exhaust side.

  • Efficiencies vary between 30% and 50%
  • Electric connection is required (circulation pump)
  • Standard plumbing equipment is used
  • Due to danger of freezing, glycol mixture is used in cold climates
  • Exhaust and fresh air streams can never mix with each other

Water heater and cooler

Coil tubes are made from copper, fins are made from aluminum. Special executions of coils are possible (copper/copper, stainless steel,  epoxy coated... ).  Collectors are made from steel or copper. Nr. of rows is from 1 to 8. Coils are equiped with air valve. Coils are pressure tested on 2MPa. Maximum working pressure is 0,6MPa., maximum working temperature 130°C. They are placed on slide rails to enable easy removal from the air handling unit. Water flow is in a counter flow arrangement to increase the heat transfer efficiency. Unless otherwise specified, pressure drop in heating coils is kept below 25 kPa and in cooling coils, below 40 kPa. If air velocity in cooling chambre higher than 2,5m/s drop eliminator is installed too.  Water collected in the drain pan is discharged through the drain pipe.

Steam heater

Coil tubes are made from copper, fins are made from aluminum completly from steel. Collectors are made from copper or steel. Heaters are produced in one or two row execution. Maximum working pressure is 0,8MPa. They are placed on slide rails to enable easy removal from the air handling unit. Due to the large difference in temperature is necessary to connect the coils to medium using the compensator to avoid damage to the expansion forces in the pipes.

Electric heater

Electric heating chamber is designed for operation in environment without danger of explosion according to EN 33 2320 in areas corresponding basic environment according to EN 33 0300. The chamber is equipped with corresponding number of stainless steal heating bars  according to the required heating power. Length of chambers depend on total installed heating power. Heater is equiped with safety and emergency thermostat.

Gas burner

The chamber is used to heat the air using burners for gas or liquid fuels. It is used in flue exchanger - fumes are completely separated from heated air.  The fuel can be used natural gas, propane, propane or ELTO (fuel oil). Burner power is modulated according to the desired temperature. Camber can be equiped by bypass damper.  Recommended control bypass damper is such that the output flue gas temperature is maintained at about 160 ° C. When controlling the bypass it must be kept the nominal air flow of chamber, writen on its label.

Direct evaporator

Coil tubes are made from copper, fins are made from aluminum and injectors are from copper. More circuit exection is possible. Standard refrigerant - R407c, R134a, R410a other possible R22, R 502, R 404, etc. If air velocity higher than 2,5m/s drop eliminator is installed too.  Water collected in the drain pan is discharged through the drain pipe.

Steam humidifiers

The chamber is used for installation of steam distribution pipes humidifier and is equipped with a drain pan for  the condensate. Steam distribution pipe and humidifier is not a standard part of delivery.

Water humidifiers

Humidification chamber is used for humidification and adiabatic cooling. Distribution jets  and humidifier is not a standard part of delivery.

Sound Attenuators

Sound attenuators may be placed at the inlet or outlet sides of the air handling units, depending on request. Attenuators containsplitters of high absorbing capacity. These splitters are made of galvanized or stainless steel with glasswool or rockwool inside. The inlet and exit portions of the splitters have a rounded shape to decrease pressure losses and noise. Splitters are placed vertically inside the attenuator. Splitters are so sized that the air speed between them does not exceed 20 m/s.


Fans are selected to meet the required air flow and pressure at the highest efficiency, minimum electric consumption and lowest sound level. In accordance with international standards, statically and dynamically balanced direct driven plug fans are used . To prevent transmittance of fan and motor vibration to the air handling unit casing, fan – motor base frame is installed on spring vibration absorbers with high absorbance capacity.


Electric motors used are asynchronous, three phase, squirrel cage type in IP 55 protection class. Unless otherwise specified, motors are 400V, 50Hz. In accordance with international standards, motors may be single speed, two speed or with frequency controller.


Diffusers are used after the fan sections in cases where there are other sections like filters, sound attenuators, etc. after the fan section, to enable homogenous distribution of air over these elements.


Empty plenum sections are used at the end of the air handling units when space is needed for air distribution, when there is more than one suction / discharge, or in special cases where maintenance is required.



LS/LR air handling units are deliverd without controll system.


Output characteristic

For exact information and selection is necesary use selection SW.