Duct-mounted ducted air conditioner: subtleties of choice and installation

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: VladiKar
Last update: February 2020

A modern ducted air conditioner with forced ventilation provides not only a comfortable temperature in the room, but also ventilation. In addition, additional modules of the air preparation system allow you to remove dust, adjust the humidity of the air.

An ionizer, an ultraviolet biologically active filter, are easily integrated into the system. Agree, it is very tempting to immediately normalize the indoor microclimate. Let's take a closer look at the channel air conditioning system.

Features of the device channel air conditioners

Traditionally, chilled air is supplied through the channels in production facilities, large stores, offices, and ships. However, air conditioners with forced ventilation for a house or apartment are installed less frequently.

This is due to the fact that the common wall split version is easier to install. But, if you want to provide the best climatic conditions in the rooms, a split system will not be enough.

For example, for a room of 25 square meters. m. 60 cubic meters are required. m. of fresh air per hour. Even for expensive wall split systems with forced ventilation, this parameter is half as much. It is impossible to integrate additional effective filters, humidifiers into wall modules. That’s why only channel systems.

Ceiling ducts
Air ducts are located between the false ceiling and the ceiling. Only a decorative grill is visible, through which fresh air of a comfortable temperature is supplied

The channel air conditioner consists of two units. On the street, a unit with a compressor is installed. An evaporator with a heat exchange circuit is placed in the inter-ceiling space or utility room.

They install a ducted air conditioner between the false ceiling and the ceiling, in the dressing room or in the utility room. The power unit is installed where the sounds from the operation of the equipment will not create problems.Due to this, the noise in the living rooms is much less during the operation of the channel system, compared with any other type of air conditioner.

The cooled air flow is distributed between the rooms along the insulated air ducts hidden in the inter-ceiling space. In addition to cooling, the duct system is able to supply fresh air in the required volumes.

Agree, this approach is optimal. No need to put the grid on the windows, the amount of dust in the room is reduced, it is easier to adjust the relative humidity.

Air ducts
The diagram shows the principle of organizing air supply channels into rooms. Using a special program, you can not only visualize the model of air ducts, but also display components in the table

As you can see, the use of a single channel type air conditioner is quite enough to cool all rooms in an apartment, house, office or store.

It is only necessary to correctly calculate the proportions of air exchange, select the power unit of the cooler of the required power, plan the integration of additional air treatment units.

Air conditioning

The first thing you need to pay attention to is heat output. According to this parameter, a device is selected based on the volume of all rooms to be cooled.

Second moment - air pressure. Long ducts with bends resist airflow. The longer the channels, the greater the air pressure you need to create. Distinguish between low-pressure (up to 50 Pa), medium-pressure (up to 100 Pa) and high-pressure (from 100 to 250 Pa) systems.

Blocks with a pressure of 100 Pa are suitable for an apartment. Some models have a pressure switch. This is convenient, because you can adjust the pressure depending on the existing duct, not much considering the parameters of the channels.

The next moment is fresh air. Not all ducted air conditioners provide room ventilation. The supply ventilation unit is equipped with heaters. They prepare the air from the street in the cold season.

Cold air must also be heated in order to prevent condensation from forming on the walls of the ducts.

Heater power - Another parameter that is important to consider when choosing equipment. In the southern regions, a unit with forced ventilation of 5 kW is suitable for a four-room apartment.

Supply ventilation unit
The ventilation unit can be purchased separately. The photo shows a typical container for heating fresh air

If you plan to install an additional filter in the channel, you should choose an air conditioner with an air pressure of 15-30% more than the recommended parameter.

Determination of the necessary equipment parameters

At the very beginning is determined air conditioning power. In practice, this parameter is taken from the passport of the air conditioner of any system. Then a proportion is compiled taking into account other volumes of the premises.

For example, a wall split system with a cooling capacity of 3.5 kW provides room cooling to 40 square meters. m. For an apartment of 120 square meters. m. a unit with a capacity of three times more, 28-30 kW, will be needed.

Quick calculation has disadvantages. Factors such as sun lighting on windows, methods of shading rooms, and the amount of thermal insulation of walls and ceilings are not taken into account. The error can be offset by a small margin in the parameter under consideration.

The required air pressure is more difficult to calculate. To do this, sketch ductwork. Branching, the total length of the channels are determined. Take into account the resistance of additional filters, air ionization systems.

In addition, you must also consider the amount of fresh air. Usually they mix 20-30% of the air from the street.

Sketch ducted ventilation with forced ventilation
A typical sketch of air flow. Knowing the scale, it is easy to determine the dimensions for calculating the air supply parameters. For the manufacture of channels requires an accurate drawing

All data is transferred to an engineer who knows the characteristics of duct air conditioners of a particular model. Having looked at the sketch of the channels, the specialist will select a system with sufficient air pressure.

As a rule, for four rooms with a total area of ​​140-200 square meters. m. models with an air pressure of 100 Pa are suitable.

Which duct is better?

Air ducts rarely pass exactly as indicated in the documentation or sketches. Sometimes you need to go around the beam, often the distances are indicated with an error. Such errors do not matter much if a corrugated pipe is used. It is cheaper than ducts with smooth walls, it is easier to mount.

But there are also disadvantages. Flexible channels sag between suspension points. In the place of attachment, the clamp compresses the pipe, reducing the cross-section of the channel. All this and the corrugated surface of the walls of the corrugation provides significant resistance to air flow. A situation may arise when airflow to the radiator of the indoor unit will be insufficient.

In this case, the automation will work and turn off the compressor. Thus, it is better to use ducts from pipes with smooth walls. They not only provide less resistance to air flow, but also become less polluted. Yes, and clean them much easier.

In addition, the insulation of the channels is an important factor influencing not only the efficiency of the air conditioning system, but also reducing the noise in the rooms. A galvanized steel duct is much easier to insulate than a flexible corrugated pipe.

Insulated ventilation ducts
The duct must be insulated. Then no condensation will form on the pipes. Air conditioning system efficiency will increase significantly

Separately, we note that the polymer for ventilation is not suitable. Pipes made of polymeric materials have a coefficient of thermal expansion of 10 times greater than that of steel. For this reason, the polymer is difficult to match with steel supporting structures. And the smell of plastic cannot be ruled out.

Air conditioning installation

The easiest way mount ducts and blocks - entrust the installation of equipment to a specialized organization that guarantees the quality of work in the contract.

But even so, it will be necessary to control a number of points:

  • the project should include easily removable panels for quick access to filters and air preparation system units;
  • fixing the ducted air conditioner, supply ventilation unit, ducts should not lead to vibration of the suspended ceiling. Bearing elements must be performed separately, without using a suspension structure profile. Then the system will work silently;
  • Electric valves should be accessible after finishing work.

During installation of the drainage system of the ducted air conditioner, the elements should be checked and compared with those specified in the instructions from the manufacturer. Otherwise, after the system is turned off, water can get into the room - relevant for high-pressure systems.

What to consider during installation?

To conduct the channels, a special large diameter diamond drill will be required. Holes with a diameter of more than 200 mm cannot be made with a conventional puncher in the panels.

You can mark the recesses yourself. Then invite specialists with a diamond drill (if such equipment is not on the farm), they will make holes quickly, without disturbing the noise of neighbors.

Drilling holes in the wall
Using a diamond drill, you can quickly make a hole for ventilation ducts in a reinforced concrete wall or in a ceiling

If there is enough experience, you can purchase ready-made air ducts and combine them into a single system, or you can order the manufacture of air ducts according to sketches ordered in a workshop working with tin.

Boxes or round ducts made of galvanized steel are made on machines, rolling joints. It will be useful to check each item upon receipt of the kit.

Given all the recommendations in the article, an experienced craftsman can carry out the rest of the work on his own.

It is useful to adhere to the instructions:

  1. The indoor unit of the air conditioner must be placed in office rooms or in the attic, if there the air temperature does not drop below 10 ° C. Otherwise, the unit must be insulated.
  2. At the junction of the channels, throttles are installed. The total cross-sectional area of ​​the holes in the chokes should be 20-30% larger than the cross-sectional area of ​​the inlet duct.
  3. To reduce noise in systems with a pressure of more than 150 Pa, a silencer is installed at the outlet of the indoor unit - a short section of the duct with a larger cross section than the main line.
  4. The outdoor unit is mounted either on the roof of the building or on the wall. After installation, experts are invited. They will check the tightness of the connections and fill the system with refrigerant.
  5. When planning installation work, take into account the terms of the warranty. Often installation of a channel air conditioner is required only by official representatives of the manufacturer.

The operation of the air conditioner is adversely affected by power surges. A voltage stabilizer or at least a cutoff should be provided.

Conclusions and useful video on the topic

In the video, they show channel conditioning systems and talk about the operation of ventilation:

Ducted air conditioning with a supply ventilation system provides better climatic conditions in the room than conventional split systems.

If you study the manufacturer's instructions and follow the advice of professionals, you can avoid mistakes when installing a ducted air conditioner. Part of the complex work should be entrusted to specialists, and the rest should be done independently. At the same time, the cost of installing equipment will be comparable to installing wall split systems in each room separately.

Do you have experience installing air conditioning and ventilation in an apartment or house? What difficulties did you encounter? Please share the information in the comments to our article.

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