What are the main functional sections of a combined air handling unit?

The combined air handling  unit consists of several sections. These include the fresh air section, return air section, primary filtration section, and medium filtration section. It also has a surface cooling water retaining section, heating section, and humidification section. The unit features an electric heating section, blower section, and silencer section. The middle section is also included. You can freely combine these functional sections to meet different air treatment requirements.

Mixing section

The air handling unit needs to use a mixing section to mix the system return air and fresh air. Usually, air valves are installed at the return air outlet and the fresh air outlet, and the two air valves are linked, that is, when one air valve is opened, the other air valve will be closed. The air valve has a manual regulator.

A maintenance door is provided on one side of the mixing section, and the direction of the maintenance door can be specified in the order. The unspecified maintenance door direction defaults to the inlet and outlet water pipe side of the unit coil section. If the mixing section only needs a flange but no air valve, no manual regulator, linkage, and electric regulator, it should be specified in the order.

Mixed filter section

The mixed filter section is based on the mixed section, with the plate type primary filter added to the section. The rest of the functions and principles of the sections are exactly the same as the mixed section.

Plate type primary filter section

The detachable aluminum alloy frame plate type primary filter, the filter material is non-woven fabric, can be washed more than ten times, and the filter material can be easily replaced, and the filter frame can be reused to reduce the user's cost. This G4 efficiency filter is often used for primary filtration in air conditioning and ventilation systems to protect the next level of medium efficiency filters in the system; it is also suitable for simple air conditioning and ventilation systems that only require one level of filtration.

Activated carbon plate type primary filter

Chemical filter - activated carbon plate type primary filter, can absorb harmful gases in the air, such as acidic gas, alkaline gas, formaldehyde, mercury vapor, radioactive gas, odor, etc. This filter has the same specifications, size, filtration accuracy and wind resistance as ordinary plate type primary filter.

The combined air handling unit consists of several sections. These include the fresh air section, return air section, primary filtration section, and medium filtration section. It also has a surface cooling water retaining section, heating section, and humidification section. The unit features an electric heating section, blower section, and silencer section. The middle section is also included. You can freely combine these functional sections to meet different air treatment requirements.

Medium-efficiency bag filter section

The bag-type medium-efficiency filter is a disposable filter that uses imported chemical fiber filter material. The filter material is flame-retardant and suitable for places with fire protection requirements, but it can be incinerated, so it meets environmental protection requirements. The filtration accuracy is F5, F6, F7, and F8, and the filtration accuracy increases in sequence. If there is no special requirement, F5 is sufficient, which is economical and practical.

The wet film humidification section 

The humidifier consists of the body (wet film), electric control box, two-way solenoid valve, filter, and water pipeline. Clean tap water flows through the solenoid valve and is sent to the water distributor on top of the wet film. The water flows down the wet film surface under gravity, moistening it. Hot air passes through the wet film, increasing its humidity and lowering the temperature. This process is an isenthalpic humidification process. Users can install a humidity controller to control the water supply. When the room humidity reaches the set value, the solenoid valve closes and stops humidification. When the room humidity drops below the set value, the solenoid valve opens and humidification resumes. This ensures automatic humidity adjustment.

Middle section

The combined air handling unit features a middle section with a maintenance door on one side. The direction of the maintenance door can be determined according to user needs. It is mainly used for daily maintenance space, such as the medium-efficiency filter section, primary and medium-efficiency filter section, and silencer section installed on the front.

Silence section

In some special occasions or user needs, a silencer section needs to be installed on the return air side or the outlet air side of the unit. Dunham-Bush silencer section adopts a sheet-type resistive silencer, which has the characteristics of good silencer performance and small wind resistance.

Exhaust fresh air section

The exhaust fresh air section can exhaust return air and inhale fresh air, and can effectively control the ratio of fresh air, return air and exhaust air. The exhaust port, fresh air port and bypass port are all equipped with air valves, which can be controlled individually or in conjunction. Manual and electric air valve controllers are available, and the control mode can be based on user requirements.

Secondary return air section

Used in process air conditioning systems or energy-saving air conditioning systems, it can maximize the use of return air. Due to the current air conditioning system's requirements and control of air quality, it is rarely used.

Air inlet section, air supply section

The air inlet section and air supply section are used on the inlet and outlet sides of the combined air conditioner,often working alongside fan coil units for optimized airflow management.These sections change the connection direction of the air inlet and outlet. For example, the filter section on the inlet side, the medium-efficiency filter section, and the silencer section on the outlet side can be adjusted. By adding the air inlet and air supply sections, the air inlet and supply direction can shift from horizontal to top direction.