Soldering tubes for an air conditioner: technology and materials

Often there are cases of failure of tube connections in a split system. The situation is aggravated by the inability to use the services of welders or assemblers. If time does not endure, the only way out is to do the soldering of the air conditioning pipes with your own hands. Of course, you can’t call this task simple, but possessing basic skills and technical knowledge, any average person can handle it.

Brazing copper pipes requires special tools and materials

Advantages and installation of a split system with copper pipes

Copper pipes are great for creating air conditioning systems. Of their advantages, we can distinguish:

• resistance to corrosion;
• tightness;
• abrasion resistance;
• smoothness of the outer and inner surfaces;
• good thermal conductivity;
• resistance to temperature changes;
• affordable cost.

During the installation of air conditioners, copper seamless pipes are used. Usually, split-system supplies include internal and external units, and everything else is purchased separately. The tubes are placed with the purpose of transporting the refrigerant through the system precisely between the above blocks. The size of copper products directly affects the performance of the air conditioner. The larger the diameter of the tubes, the higher the value of this characteristic of the device is higher.

Air conditioners are installed in modern buildings as follows:

• locations of indoor and outdoor units are selected;
• for laying tubes and electric cables, a hole with a diameter of 40 mm is drilled in the wall;
• mounts of external and internal blocks are mounted;
• the tubes are laid, cut, and their combined ends are expanded. Result of the last operation
• looks like tubes with nuts on;
• the tubes are connected to the indoor and outdoor units;
• a pipe is laid to drain the condensate;
• the system is evacuated;
• The air conditioner is plugged in.

Copper pipes are environmentally friendly and not subject to corrosion, therefore they are considered the best option for air conditioning systems

Low temperature soldering. Features

If a rolling compound loses tightness to restore it, many professionals prefer not welding, namely soldering copper tubes. In favor of this choice, they give the following arguments:

• efficiency of work;
• copper pipe soldering apparatus is cheaper in comparison with welding equipment.

The resulting compound is characterized by:

• reliability;
• strength;
• resistance to high mechanical and temperature loads.

Low temperature brazing is usually carried out using a propane burner. The pipe is heated to a temperature of 200-250˚C. If soft solder is used, the burner flame must be constantly moved to heat evenly.

Good to know! The following substances can be used as solders of this type: L-SnCu3 (S-Sn97Cu3) and L-SnAg5 (S-Sn97Ag5). Using these materials, the brazing of copper pipes for the air conditioner is excellent, since these chemical compounds provide resistance to mechanical stress and corrosion.

The technique for performing this operation has its own characteristics. So, if the solder does not melt when touched with a bar, heating should continue, constantly moving the flame. When the solder begins to melt, the flame should be removed and wait until the solder penetrates the mounting gap. The gap is completely filled, so do not introduce additional volumes of solder, as the excess that appears will flow inside the pipe and thus reduce the useful clearance.

For low-temperature brazing, soft solder is used, produced in coils.

Of the other features of low temperature brazing, the following should be noted. In the case of using standard pieces of soft solder, it is necessary to control that their size is equal to the diameter of the connected product. Giving the required areas of solder a L-shaped configuration will provide the convenience of performing rations of copper pipes.

One of the significant advantages of this method is that the strength of the raw materials - copper - is maintained at a high level. The main drawback is the worst mechanical characteristics of the compound.

Features of high temperature soldering

This technology is applied if during operation the pipeline will be subjected to high temperature loads. High-temperature soldering is carried out exclusively by the flame method.
When copper-phosphorus solder is used, you can do without flux. Desired burner flame temperature. The flame itself should be medium. Heat copper tubes evenly. This approach will ensure good solder filling of the installation gap. In this case, the parts can be fixed in any position. To check the degree of readiness of the connection, you can use a solder bar: when the soldering of copper tubes of the air conditioner is completed, when it touches the created joint, it should melt. This phenomenon will indicate that, having acquired a liquid-like state, this substance filled the gap completely.

To successfully implement this method at home, you can use a building hair dryer. Moreover, with this device, professionals just recommend soldering the tubes of air conditioning systems because of their small size. It’s easy to work with a hairdryer, the soldering algorithm is similar to manipulating a burner.

For high-quality soldering, sufficient heating of the workpiece is important so that the solder uniformly fills the joint

The advantages of high temperature brazing are as follows:

• Compared to using soft solder, the joint width can be reduced;
• operation in systems with high temperature is allowed;
• increased strength of the seam.

The disadvantages of the experts include:

• without the qualifications and experience to implement this method is very difficult;
• annealing of copper occurs.

Materials and equipment

To perform the soldering of copper tubes, nothing unusual or expensive will have to be purchased. You will need the following fixtures and materials:

1. Faskosnimatel. With this important tool, the burrs are removed from the inner and outer edges of the pipes cut to the required dimensions.

Important! If the burrs remain, the procedure for joining the pipe and fitting will be much more complicated.

Modern industry produces two types of chamfering machines: in the form of a pencil and in a round case. A more expensive tool is the second type. But its use increases usability. You should also be aware that the round beveller is designed to work with pipes with a diameter of not more than 36 millimeters.

2. Soldering iron. Usually, a special propane compact burner is used as such. A simple welding device equipped with a switching device is included in the scope of delivery.

3. Pipe cutter. Without the use of such a device, it will not be possible to “gently” cut copper tubes. This is due to the increased softness of copper products, which is why any “wrong” pressure can cause their deformation. The cost of a pipe cutter depends on the diameter of this type of pipe products intended for processing. Another significant factor affecting the price is the availability of additional options that make it possible to use such a tool for copper pipes in hard-to-reach places.

Copper pipes need to be cut only with a special tool so as not to deform the cut

4. Steel brush and special brush. With the help of these accessories, high-quality cleaning of surfaces and cavities of the pipes being brazed is carried out from oxides and contaminants formed during this operation.

5. Solder paste and flux. These liquid or solid formulations do not allow air bubbles to penetrate the joint. In addition, thanks to them, the degree of adhesion of the solder to the surface of the pipeline element is significantly increased.

6. Solder. For low temperature soldering, conventional tin wire is used as such. If it is supposed to carry out high-temperature soldering, then in this case a copper wire will be used, which includes about 6% phosphorus. The presence of this component ensures the melting point of solder at + 700 ° C. This is an average indicator.

In addition, a kit for soldering copper pipes should contain a set of devices for the general construction group. These include tools such as:

• hammer;
• level;
• marker;
• brush;
• roulette.

How to solder copper tubes

Above, only some features of the soldering procedure were considered. The process itself involves certain actions.

These actions are performed in strict sequence, preparatory manipulations are required:

• removal from the sites of the alleged soldering of the oxide film. The dust generated during processing must also be removed;
• application to the prepared surface of the flux;
• connection fitting to the pipe. The size of the gap is not more than half a millimeter;
• heating the junction for 15-20 seconds.

Advice! It is not necessary to conduct solder during heating over the entire diameter, it is necessary to conduct it only along the edge of the joint, since it will penetrate into the gap.

Upon completion of soldering, the system is flushed without fail. The need for this event is due to the fact that flux residual contamination can provoke the passage of the metal corrosion process, which, in turn, will lead to the failure of the air conditioner.

Do not forget another nuance. To prevent heat loss during operation of the air conditioner, copper pipes must be insulated. Rubber insulation works most effectively. Its low thermal conductivity contributes to the reliable operation of the unit. In addition, the compressor load is reduced.