VEX300T with counterflow heat exchanger

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VEX300T is a range of compact air handling units in which all ducts exit the top of the unit. In addition, connection of water to the cooling/heating coil is place in the top of the unit, just as the condensate drain is connected on the front of the unit. Therefore, VEX300T can be placed closely to other technical equipment, since the end walls do not need to be accessed for service.

The range consists of 5 sizes, with an option for the EXact2 control system or prepared for a third party control system.

VEX300T has been construced with integral heating or cooling coils, which reduces the installation costs. It is also possible to choose prefiltration of the supply air.

The design is optimised for compactness, temperature efficiency, airflow and energy consumption. Despite being very compact in size, the unit is easy to service, e.g. for filter change, cleaning, etc.

VEX300T must be located indoors and can be used for all purposes where the special top-duct construction will aid installation.

Operating conditions

In principle, EXHAUSTO VEX units are designed for use in comfort ventilation - i.e. under ordinary operating conditions.

Where ventilation solutions are required for rooms with high air humidity - e.g. due to humidification, we recommend you make a test calculation with one of our calculation programs. If the calculation shows a risk of condensation after the heat exchanger, an assessment must be made whether the operating conditions can be changed, or whether the unit must be modified to allow condensate to drain off. This is particularly relevant for VEX100CF.

Contact EXHAUSTO for advice on this.

Unique frost protection

VEX3300T Bypass de-icing

The VEX300T is designed with de-icing bypass. If there is a risk of icing, then a certain amount of outdoor air will bypass the heat exchanger and go directly to the after heating coil. This increases the demands on the after heating coil’s output. However, it avoids a costly preheating coil. The drawing below is an example of a de-icing situation, where 20% of outdoor air is directed through the bypass damper.

VEX300T De-icing gb

Heating coil and de-icing function:
The de-icing situation is shown above, a heating coil is included here. A coil is absolutely necessary, in order for the de-icing function to work correctly. Without the heating coil, the de-icing process will cause the temperature of the supply air to fall and sooner or later the VEX unit will stop because of icing.

The heat exchanger has two forms of frost protection: temperature-controlled or pressure-controlled. The actual de-icing can take place in several ways, depending on whether an after heating coil has been fitted. An after heating coil is always recommended to maintain continuous ventilation.

Which method is used when?

Frost protection method De-icing starts when Recommended for use in
Standard on VEX310T-330T
Temperature is below the set value,
e.g. tice < 0 °C
Residences, changing rooms, and
rooms with variable humidity in the winter.
Standard on VEX340-350T
Pressure across the heat exchanger exceeds the set value, e.g. + 45 % Offices, schools, after-school club facilities,
and rooms with low humidity in winter.

Temperature-controlled frost protection Tice

The control system has temperature-controlled frost protection as standard. It is an inexpensive solution and provides sufficient frost-protection in some situations.

A temperature sensor is fitted inside the heat exchanger and if the temperature falls to a pre-set value, de-icing begins. This temperature level is factory set to 0 °C but it can also be changed to a new value via the control system.

Temperature-controlled frost protection triggers the de-icing process even if there is no ice in the heat exchanger. 

Pressure-controlled frost protection (requires accessories AFC (airflow measurement) and DEP (frost protection - pressure))

The control system monitors the actual airflow and also the pressure drop across the heat exchanger. If ice forms in the heat exchanger, the pressure drop across the heat exchanger will increase and when it exceeds a pre-set value, de-icing begins.

Pressure-controlled frost protection only starts de-icing when ice has actually formed, regardless of whether there are sub-zero temperatures.

Capacity curves


Below illustrates which capacity ranges individual VEX sizes cover. To calculate the actual capacity data, use our product selection programs.


Sound level

VEX300T, extremely quiet air handling units

The VEX units in the VEX300T series are extremely quiet, with a far lower sound level than similar products on the market.

For exact sound data, see our calculation programs.



The compact unit is designed in accordance with German hygiene standard VDI6022, which ensures units are accessible for service and the formation of mould or other bacteria that could  negatively impact air quality is prevented. Read more about this standard in the Certificates section.



Cabinets are made from Aluzinc® AZ185 class C4 in accordance with EN/ISO12944-2 and insulated with 50 mm mineral wool. This results in low noise emissions to the surrounding environment/installation room.

The panel design minimises the formation of thermal bridges in the unit.

Motor sections 

VEX320330 ventilatorsektion

The motor sections are mounted in vibration dampers, which reduces noise in the ducts  and eliminates the need to fit flexible connections between the unit and the duct system.

The motors are of type EC and are extremely efficient. They comply with the requirements of the Ecodesign Directive.

Fan impeller 

VEX300T is equipped with an optimised centrifugal fan impeller with backwards curved vanes. 

The impeller is made from a composite material and its shape provides great performance with 
low energy consumption.

Heating coil/cooling-heating coil

 VEX100 varmeflade

The VEX300T range is supplied with an integral heating coil or cooling-heating coil

HE: Electric heating coil
HW: Water heating coil
CW: Cooling-heating coil (option for cooling in summer and heating in winter)
DX: Cooling-heating coil (option for cooling in summer and heating in winter)

See more about cooling/heating coils under the technical data for the size in question.

AHUC - Main board 


The easily accessible  connection box with built-in switch disconnector ensures easy access for connecting and adjusting.

Further information in the manual: "Guide to electrical installation of VEX300T"


Panel filters 

Panel filters are easy to replace and can be ordered as ePM1 80% (F9),  ePM1 55% (F7), ePM10 65% (M5) and Coarse 65% (G4).



VEX300T prefilter place

Prefiltration on supply air side

It is possible to insert a filter (Depth: 48 mm) ahead of the standard filter on the supply air side. Placing a coarse filter ahead of the fine filter reduces soiling on the fine filter. Depending on the outdoor air and the desired quality of the supply air, this can be a good idea/option.

Prefiltration filters are available in classes:  ePM1 55% (F7), ePM10 65% (M5) and Coarse 65% (G4). Pressure drop, etc. can be calculated in the product selection programme EXselect.



VEX300T Energy-efficient ventilation

The design of the unit has placed particular focus on smooth airflow through the unit in order to achieve the lowest possible pressure loss.

Counter flow heat exchanger 


The VEX300T counter flow heat exchanger is made of aluminium. It is designed to ensure the ratio of heat recovery and pressure loss is at an optimum, i.e.
extremely high temperature efficiency is achieved at low levels of energy consumption.

- Efficiency level without condensation: 80–85 %
- Efficiency with condensation: Up to 94 %

EC motors 

VEX320330 ventilatorsektion The combination of modern EC motors  and an  optimised centrifugal impeller delivers extremely low energy consumption and greater output at the same time.

Energy labelling 

An energy label that states the energy class of the unit in relation to defined operating conditions is available via our product calculation programs.



EXHAUSTO puts great emphasis on providing accurate data. So we use a third party to measure and check our data.

Eurovent certification

All data provided with the VEX100/VEX100CF/VEX200/VEX300 model has been measured.

The units have completed a major test programme in our development department and all of the capacity, efficiency and sound data is collected via testing and in real operating situations.

In accordance with EN1886 and EN13053, Eurovent has tested and certified that EXHAUSTO VEX units meet the following requirements and classes:
Unit’s stiffness:
Air tightness class at -400 Pa:
Air tightness class at +700 Pa:
Filter bypass leakage:
Insulation class:
Thermal bridge class:

L1 (M)
L1 (M)
T2 (M), U1≤1,0
TB3 (M)

This means that a third party has checked that the data that our product calculation program produces complies with the real performance of the unit. Eurovent checks the data by selecting a unit at random and testing that unit at their own facility. If our stated data complies with the Eurovent's test results, we retain our certification. This guarantees the customer that our data is valid.

VDI 6022 - German hygiene standard

EXHAUSTO has designed its units in accordance with the German hygiene standard VDI 6022.

VDI 6022 requirements
The unit's design must make cleaning easy. There may not be areas that cannot physically be cleaned and voids that are inaccessible must be sealed. Plates must be deburred to ensure edges are smooth and corners must be rounded to avoid the risk of injury when cleaning.

In addition,the condensation tray must decline to the outlet, so that water cannot remain in the unit. It is important that the condensation outlet is connected to the drainage system on a horizontal surface.

All non-metallic materials (e.g. seals, filters), are tested to show that they do not promote growth of mould spores and bacteria.

Because the unit is designed in accordance with VDI 6022, it is both more hygienic and easier to clean.


Ecodesign - EU requirements for documentation, energy consumption and labelling of ventilation units.



General information

We have made a compilation of extracts from the Ecodesign guidelines, read more about Ecodesigne here.


Ecodesign data

You will find links to Ecodesign data for the individual VEX sizes under the product name and in the Download section, where we have located Ecodesign data under EU/ECO declarations.


We would point out that the values stated in the declarations have been calculated for a specific operating point.

If a different operating point is desired, we refer to our calculation programs - here you can see whether the desired unit meets the requirements for your operating point and you will find the associated Ecodesign data.

SPLIT version

VEX300T is available as a split version.

With some projects, limited space means that internal transport of the air handling unit is difficult or impossible. This is why the VEX300T is available as a split version. It means that the air handling unit can be assembled and tested at the factory as normal – just without sealant. The air handling unit can therefore be easily taken apart at the installation site, transported as single sections, assembled, sealed and commissioned.

The table below shows the dimensions of the largest section (counterflow heat exchanger) and largest cabinet section, so that it can easily be determined whether there is sufficient space to allow internal transport.

Section Dimensions VEX310T VEX320T VEX330T VEX340T  VEX350T
Counterflow heat exchanger Height [mm] 312 312 394 674 957
Length [mm] 537 537 619 899 1182
Depth [mm] 300 2 x 300 2 x 325 2 x 310 2 x 355
Weight [kg]
 7,2 2 x 7,2 2 x 19,2 2 x 19,8 2 x 35
Biggest cabinet section Length [mm]  1140 1140 1500 1900 1750
Width [mm]
1200 1200 830 825 1200
Motor section Weight [kg]  2 x 4,1 2 x 6,4 2 x 9,2 2 x 9,5 2 x 20


VEX300T SPLIT version



A wide range of accessories are available with the VEX300T

Closing damper - LS 

LS runde kanaler 150 100 Closing damper with spring-return for indoor or outdoor fitting.



VEX330H sokkel A base with feet can be ordered.


 Water trap

EXHAUSTO also offers a water trap for the unit's condensation drain in dimension DN32.

SIPHONUP (negative pressure) for connection to condensation outlet from the unit.
SIPHONOP (overpressure) for connection to any cooling coil in the supply air duct.

SIPHONHE02 (accessory) hot-wire is used to keep the water trap and water pipe free of ice. A thermostat is fitted to the hot wire to ensure low energy consumption.

Inspection windows

VEX300T med inspektionsruder

VEX340T-350T is available with inspection windows as 
required by VDI6022.

When operating with HE fan:

Requirement for AFC - airflow control


Airflow measurement AFC
VEX310T-320T-330T: Optional equipment
VEX340T-350T: Standard

Read more about function under:
EXact2 control system for VEX300T, section "Unit function overview"

For third-party control system


Simplified diagram


VEX300T FAA simplified diagram

Freedom to choose!

VEX300T can be connected to other third-party control systems. This means the unit can be integrated to a control system from another supplier. Designed for quick and easy integration.

A typical VEX300T solution connected to a third-party control system:

  • Air handling unit with counter flow heat exchanger
  • Compact unit
  • Integral double bypass with 24 V motor (BP1)
  • Free-moving B-impeller 
  • Filter classePM1 80% (F9),  ePM1 55% (F7), ePM10 65% (M5) and Coarse 65% (G4)
  • EC motors class IE4
  • EC motor control 0-10 V (MC)
  • Airflow measurement points on fans led to connection box
  • Filter pressure measurement points on fans led to connection box
  • Cables for MC and bypass damper run to terminal board.


Add all about the product series VEX300T with counterflow heat exchanger


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Calculation programs

Use EXHAUSTO's free calculation programs for calculating ventilation plant and system solutions

Go to Calculation Programs
Teaser ecodesign

Ecodesign Directive

EXHAUSTO VEX air handling units and fans comply with the Ecodesign Directive. Read more here.

See more about Ecodesign here