The necessary distance between the air conditioning units: basic rules and regulatory requirements for installation

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Tatyana Zakharova
Last update: January 2020

In the process of installing air conditioners, it is important to consider many aspects, including the manufacturer's recommendations. Agree that a properly installed unit works more efficiently, and its service life is much longer.

The technical conditions include the choice of the length of the freon track of the split system - a copper pipeline connecting the internal and external modules. There are boundaries, violation of which leads to a sharp decrease in productivity and breakdowns of key components.

In this article, we will consider what the necessary distance between the air conditioner units should be, and find out whether it is possible to increase the length of the connecting line without loss of functional qualities.

The principle of operation of the split system

First, find out how a household split system works - it will be easier to understand why the installation nuances are important.

As you know, a home air conditioner of a traditional design consists of two blocks: one of them is installed in the room, the second is fixed on the street, on the outside of the wall, in the attic or anywhere else ..

Split system device diagram
A line is laid between the indoor and outdoor units along which refrigerant circulates. This is a closed system of copper tubes filled with freon

The process of cooling air in a room occurs due to the continuous movement of freon and its transition from a gaseous state to a liquid state, and then vice versa. When the refrigerant is in a gaseous state, it absorbs heat, and in the liquid phase it releases.

The condensation process, that is, the transition to a liquid state of aggregation, occurs at high temperature and pressure, and boiling, at which the gas evaporates, is characterized by low values.

The principle of operation of the split system
A diagram showing the circulation of refrigerant in a closed circuit between two modules: the evaporator is located in the body of the wall unit, and the condenser is inside the outdoor unit

The heat transfer process occurs as follows. The compressor draws steam from the evaporator (zone 1-1), compresses it and directs it to the condenser (zone 2-2).In this case, the refrigerant is compressed to 20-25 atm., And its temperature rises to +90 ° C. There is cooling and condensation.

From the air conditioner (3), the refrigerant, already in the liquid state, is returned to the evaporator (4) through the flow regulator under low pressure conditions. The internal air heats the liquid, boiling and transition to steam occurs. And so the process repeats endlessly.

The transition of the refrigerant from one state of aggregation to another occurs both in heat exchangers and in pipes. In order for the process to start and end on time, a certain length of the trunk is necessary - this is why it is important to take into account the length requirements established by the developers of the equipment. With device and the principle of operation of a typical air conditioner figured out, and now move on to the norms and rules for installing its blocks.

The length of the freon highway

Climate technology users often argue about the distance from the outdoor unit to the indoor unit, and then experiment with the installation. They can be understood - sometimes the features of the interior or the arrangement of rooms require an increase in the length of the pipeline.

Indoor unit near the window
Traditionally, the internal wall module is fixed under the ceiling, not far from the window. This is due to the limitation of the length of the freon line and the installation conditions of the external unit

But professional installers know for sure that you can’t arbitrarily increase or decrease the length of the pipeline. Indeed, a deviation from the required parameters immediately affects the performance of the air conditioner.

We will find out what the installation standards should be and why they can not be changed.

Norms of distance between blocks

Installation standards are set by the manufacturer. If you take the instructions, then in the installation section you will find schemes and operating parameters that you need to focus on during installation.

As a rule, indicate the maximum length of the highway, nothing is said about the minimum. But complete with the blocks you will find copper tubes for their connection - they can never be shortened.

Copper pipe for air conditioner
Copper is recognized as the best material for the manufacture of freon highway. If during installation, the tubes are damaged, for the replacement you need to use similar and no other

The length of the pipeline depends on the model.

For household split systems with an internal wall unit, the following standards apply:

  • maximum distance between blocks - 15 m or 20 m (less often - 10 m);
  • minimum distance between blocks - 3, 4, 5 m (length of pipe included).

The exact data is indicated in the technical documents for the specific model.

Technical table
An example of how the technical data looks in the instructions. Freon line lengths for the Dahatsu DA-09H model without charge and subject to additional refrigerant charge

According to the parameters indicated in the table, it is clear that when extending the route, additional filling of the circuit with freon is required.

If the split system is equipped with a 5-meter pipe, it cannot be shortened. What to do if the distance between the blocks is only 3 m and the tube is 5 m? You just need to carefully wind it in large rings, without breaking and twisting, and hide the remaining 2 m in one of the blocks.

Pipeline too short

If the manufacturers do not indicate the minimum length of the freon line in any of the available sources (paper or electronic instructions, video), focus on the generally accepted value - 3 m. In short, you can’t make a route in short.

If we recall how the process of transition of the refrigerant from one state to another occurs, we will understand that a short pipe is simply not enough to completely transform the substance. Freon, which did not have time to turn into gas in the evaporator, enters the compressor in the form of liquid, which should not be allowed.

Split system compressor in a repair shop
Too short a line can lead to water hammer, as a result of which the valves will “fly out”, the compressor will fail, and you will have to pay dearly for the repair of a new split system

The consequences of installing too short a pipeline are different:

  • breakdown of air conditioning parts;
  • transition of vibrations from the outdoor module to the wall;
  • noises uncharacteristic for the air conditioner - gurgling freon in the pipeline.

These troubles can be eliminated only by increasing the length of the pipeline. As you can see, a small installation nuance was very important.

More than standard distance

As you already know, the maximum length of a freon line is limited to 20 meters. This value is relevant for home models with an average output of 2.5-3 kW. But for semi-industrial units from 8-9 kW, other boundaries are used - the length of the pipeline increases to 50 m.

We can conclude that the distance between the blocks of split systems is directly related to such a technical characteristic as performance.

Indoor unit cassette split system
If it is necessary to provide cool air to rooms located far from the outdoor unit of the split system, other types of air conditioners are installed - for example, duct or cassette

The most dangerous thing that can happen if the pipeline is too long is the pressure drop. Moreover, both sections - gas and liquid - are expected to have negative consequences.

If the gas pressure drops before it enters the compressor, then at the outlet it also becomes lower. As a result, the temperature decreases, freezing occurs.

There is no special function for heating the line, so the compressor overheats and breaks due to the load. Features of compressor diagnostics and how to repair it are discussed in the article: How to build an air conditioner route: communications device specifics

The decrease in pressure in the pipeline with liquid freon leads to an increase in the proportion of gas. A high gas content increases the speed of the refrigerant, which leads to an even greater pressure drop. In such conditions, the normal functioning of the air conditioner is simply impossible.

But there is one way out: to reduce the pressure loss in the line, increase the diameter of the copper pipe. To do this, use the formula:

Formula for calculating pressure
If the speed value is reduced by 2 times, the pressure loss will decrease by 4 times, therefore, the length of the pipeline can theoretically be increased by 4 times, in practice - 2 times

Professional installers advise increasing the length of the freon line only in horizontal areas.

In order not to resort to complex calculations, it is recommended to increase the diameter of the gas pipe (it is slightly thicker) by 1 size: that is, replace 3/8 with 1/2, 1/2 to 5/8, etc.

Air conditioner extension circuit
An example of replacing pipes with wider ones when extending the route to 40 m. Mounting nuance: on the vertical section, you must leave pipes of the diameter specified in the instructions

We do not recommend doing the usual installation of an air conditioner or replacing pipes yourself. Experienced specialists know better what to do in difficult cases and avoid malfunctions.

Altitude difference between blocks

In addition to the length between the modules of the split system, a certain height difference must be maintained. It is always indicated in the instructions and for household models it is usually not more than 5 m, less often - 10. Large values ​​are typical for semi-industrial and industrial models - up to 20-30 m.

Blocks of the climate system VRV
The highest elevation values ​​for industrial climate systems such as VRV. The difference in height between the indoor and outdoor units can reach 90 m

If the length of the freon trace can be slightly increased, then experimenting with height is prohibited. For this reason, the outdoor unit is most often installed 2-3 meters below the wall module.

The owners of city apartments have little choice - next to the balcony or window. Owners of one-story cottages sometimes install an external module directly on the ground, on special supports. We talked in detail about choosing the optimal place for installing the air conditioner in this our article.

Conclusions and useful video on the topic

An example of choosing the installation location of a split system in accordance with the requirements of the manufacturer. Installation Basics:

Errors in reducing the length of the track:

It is much easier to make an independent installation or control someone else's work, if you know the principle of operation of the equipment and the subtleties of the installation. As you have seen, the choice of the length of the freon highway is not a whim, but a technically verified condition for the correct operation of the split system.

We do not recommend departing from the parameters specified by the manufacturer. But if there is no other way and you need to increase the length of the pipeline - be sure to contact the specialists.

And at what distance are your air conditioning units installed? Tell us about your personal experience in choosing a place for installing blocks outside and inside the building. If you still have questions about the topic of the article, do not hesitate to ask our experts and other visitors to the site - the feedback block is located below.

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