Buying a split-system and calling the installation team to install it, we all want the climatic device to relieve the heat in summer, and from the cold in spring and autumn. And to still work properly for 6-7 years at least without maintenance. Is that correct?
If you are protected from factory defects by the manufacturer's warranty, then from the negligence of installers - only understanding the procedure for installing a split system. In 70% of installation work, the “air conditioner” masters simply do not perform vacuuming of the air conditioner, since it is long (about 30-60 minutes) and expensive (a good vacuum equipment costs more than 12 thousand rubles). rub.).
Meanwhile, this "minor" installation omission seriously affects the service life of the split system. Let's talk about the vacuuming of air conditioning systems in detail.
The content of the article:
-
Purpose of evacuating the split system
- Air mixed with freon
- Moisture in A / C compressor oil
- How is the vacuum of the climatic device performed?
- Errors when vacuuming split systems
- Pumps for evacuation of split systems
- What is the best evacuator to choose?
- Homemade vacuum pump
- Conclusions and useful video on the topic
Purpose of evacuating the split system
Most multi-brand split systems can easily handle six years or more uptime under two conditions. The first is the absence of factory defects in split units. The second is correct installation of the air conditioning system in place.
After placing blocks (outdoor, indoor) in places, connecting the flared ends of copper pipes with taps of the external and fittings of the internal split-modules, the work of the installers looks like completed.
However, before letting the freon refrigerant into the pipe line and turning on the air conditioner, manufacturers of climatic equipment recommend evacuating air from the connecting pipes and the circuit as a whole.
Every unit and practically every working element of the refrigeration circuit interacts with the refrigerant. Therefore, the composition of freon should not be affected by either air gases or moisture.
So is it necessary to vacuum a home air conditioner or is it an unnecessary operation, as many split system installers confidently declare? Let's see.
The working processes of the refrigerant circulating through the tubes and units of the air conditioner are precisely balanced by the manufacturer. Cycles of compression, condensation and subcooling of freon occur under strictly defined aggregate states of the refrigerant.
The following happens:
- The vaporous refrigerant follows a thick pipe from the evaporator (split indoor unit) to the condenser (outdoor unit), where it is pumped by the compressor. There, freon is blown by a fan and cooled;
- The liquefied refrigerant is directed through a thin tube to the evaporator of the indoor unit. Its pressure is reduced by a thermostatic valve;
- In the indoor unit, freon boils and actively evaporates, absorbing heat. The cold heat exchanger is blown by a fan that circulates the cooled air throughout the room. Then the refrigerant is pumped from the indoor unit to the outdoor unit - the operating cycle is repeated.
But air and moisture mixed with freon change its operating parameters, seriously interfering with the operation of the air conditioner. How do these extra components end up in the refrigerant?
The copper pipes connecting the climate system modules contain air after they are connected to the split-blocks. What is also important - there is always moisture in the air, which also affects the characteristics of the air conditioning device negatively. Let us explain how water and air affect the freon refrigerant and the compressor of the split system.
Air mixed with freon
Having remained in the tubes of the split system (i.e., vacuum was not performed), atmospheric air accumulates in condenser of the "street" unit, since the receiver blocks its further passage (as a vaporous (non-condensed) freon).
Neither purging with freon, nor relying on the dryness of the summer atmosphere, nor the assurances of installers - nothing will provide a long service life of your air conditioner, in addition to correct installation with freon vacuum highways
The air collected in the condenser significantly increases the pressure required to condense the refrigerant. In addition, an air film appears on the condensation surface, which greatly impairs the selection of heat from the condensed freon.
Since the heat removal is deteriorated, and the volume of the incoming refrigerant remains the same, the condensing pressure rises, requiring an increased compression ratio from the compressor. As a result, unacceptably high pressure and temperature are observed at the outlet of the compressor, which sharply accelerates its operating time.
Moisture in A / C compressor oil
In addition to the main refrigerant material, the split air conditioning circuit contains synthetic polyester oil. As with other refrigeration equipment, POE oil provides lubrication to the moving parts of the compressor.
The oil intended for lubrication and sealing of compressor units is made on the basis of polyesters. It is contained in the compressor container. During operation, oil enters the refrigeration circuit in a small volume - about 5-10% of the total.
Covering the walls of the refrigeration circuit tubes with a thin layer, the oil film, in addition to removing heat, contributes to improved circulation of freon.
A characteristic sign of refrigerant clogging in a split-system with atmospheric moisture is a frozen tube of the gas phase of the circulation of freon
However, ester oils are highly hygroscopic. If the water content of POE oil exceeds 30 ppm (30 parts per million polyester oil), its performance will deteriorate dramatically. This may be followed by a jamming of the compressor - the most expensive unit in the split system.
The increased water content weakens the dielectric strength of the polyester oil, leading to breakdown of the compressor winding.
In the presence of water in the oil at a level above 30 ppm and in the presence of fluorine, chlorine and bromine atoms contained in R410 freon hydrolysis processes develop, causing the formation of active acids - hydrochloric (HCl), hydrofluoric (HF) and hydrobromic (HBr). Even in small quantities, these acids will corrode the refrigerant pipes due to chemical corrosion.
Finally, water that is not dried by evacuation and saturated with synthetic oil will cause internal icing of the thin tube of the freon circuit near the external unit.
This is especially evident when the split-system operates for heat during the off-season. As a result, the compressor runs with insufficient refrigerant, quickly overheats and shuts down (protection is triggered). In the worst case, the compressor burns out. With rules compressor performance checks and its repair will be introduced by the article we recommend.
Note that it is impossible to remove moisture from the synthetic oil contained in the air conditioner by vacuum. One option is to drain the moisture-laden POE by replacing it with new oil.
How is the vacuum of the climatic device performed?
To perform the procedure for drying and de-airing the air conditioner circuit, you will need the following equipment: gauge (collector) station, also used for refueling split systems freon; vacuum pump; screwdrivers and wrenches.
To let the freon into the circuit after evacuation, you need two hex keys (usually 4 mm).
It is important to precisely follow the order of connecting the hoses of the gauge manifold with the outlet fittings of the vacuum pump and the refrigerant cylinder.
Let's take a look at how to evacuate a newly installed (new) two-unit air conditioner in order:
- We connect the hose (blue) of the gauge station from the fitting under the low pressure gauge to the service port on the valve of the external block of the split system (thick tube of the "gas" phase refrigerant). The taps on the split-block valves (opened with a hex key) must be closed;
- We connect the filling hose (yellow) from the middle fitting of the collector station with a vacuum pump;
- We turn on the pump;
- We open the low pressure valve on the gauge station (blue, under the blue pressure gauge). The vacuum process has started;
- We are waiting from 15 minutes to half an hour (the longer the freon line, the longer) until the pressure gauge needle goes below zero;
- We turn off the pump and expect maximum cleaning of the atmosphere in the split-system line from moisture and air gases. It will take more than 30 minutes;
- We close the blue valve at the gauge station, only after that we disconnect the vacuum pump;
- Without opening the blue valve and without removing the blue hose from the valve on the "street" split-block, open two taps on the external block of the air conditioner with hex keys and let freon into the circuit. Then you can disconnect the blue hose.
Watch the arrow on the blue pressure gauge. As the degree of rarefaction of the refrigeration circuit atmosphere increases, it should slide to zero. Depending on the power of the pump and the length of the freon line, the vacuumization will take 15-20 minutes.
Then the pump must be turned off (do not disconnect!) And follow the arrow of the pressure gauge for 30 minutes. The pressure is maintained - everything is fine, you can fill the circuit with refrigerant. Models of vacuum pumps in the middle price range and above are equipped with a vacuum gauge scale, it is especially convenient to track the degree of rarefaction of the atmosphere on it.
Errors when vacuuming split systems
In the absence of a vacuum meter, air conditioner installers are guided by the pressure data on the pressure gauge - they wait for the arrow to fall below the zero mark, after which they complete the vacuumization. This is the deepest mistake!
Reaching the minus limit on the low pressure gauge is not the purpose of evacuation. To eliminate moisture, the high-vacuum atmosphere in the circuit should be kept for more than 30 minutes after the pressure gauge goes into minus
You should continue to maintain the atmospheric vacuum in the freon circuit for at least half an hour with the pump turned off in order to evaporate and remove moisture from the climatic device. This operation is called crimping.
If during the vacuum pressure test the blue pressure gauge shows spontaneous pressure normalization - the arrow goes from zero to one - depressurization is observed. We check the fastenings of the hoses to the gauge system, to the taps on the street split-block and the vacuum pump.
The new split-system is regularly filled with freon isolated in the external block. After completing the evacuation, it is necessary without disconnecting the hose from the service connection (the vacuum in the circuit must be maintained), remove the plugs and open the taps with a hex wrench, letting the refrigerant into the circuit
Not finding a weak fastening between these devices, we are looking for an installation defect - overtightened or loose nuts on the copper pipes of the line, or poor-quality rolling of their ends.
Vacuuming the refrigerant line is effective if only the temperature in the area of the outdoor unit of the air conditioner exceeds +15OWITH. Water at low outdoor temperatures in a rarefied atmosphere does not evaporate, but freezes - it is almost impossible to remove it from the pipe line.
For example, at +30O40 mbar is sufficient to evaporate the water present in the refrigeration circuit. And at 0OWith, it will be necessary to reduce the pressure to a deep vacuum - below 6 mbar, otherwise there will be no evaporation and moisture removal.
The colder the atmosphere at the location of the external air conditioning unit, the higher the vacuum and the longer it takes to remove moisture before starting into the freon circuit
Therefore, vacuuming must be performed either in the warm season, or with a special heating of the external heat exchanger. split-block (for example, a heat gun) during the entire time while in the prepared freon line the vacuum is maintained.
Note that purging the circuit with freon, practiced by careless installers, cannot give the proper result in eliminating air and moisture. This is just a pointless consumption of freon, by the way, not cheap.
Pumps for evacuation of split systems
To remove a larger proportion of gaseous substances from the collected, but not yet filled with freon compressor and condensing unit, a special device is required - a vacuum pump. The procedure for evacuating air from a split system can be performed by pumps of two main types - low vacuum and high vacuum.
For splits up to 7000 BTU, a single-stage vacuum pump is suitable, for more powerful ones, a two-stage one is needed, and for multi-zone systems - only an ion-getter one. You will definitely need a gauge station with hoses and fittings for 410 freon
Let's repeat once again: do-it-yourself vacuuming of the air conditioner is possible, but this work cannot be done without a vacuum pump.
Types of low vacuum pumps:
- Rotary vane (single stage). They are characterized by low noise during operation, the ability to adjust the residual pressure, and simple design. Their disadvantages are the need for periodic replacement of consumables (for example, oil);
- Two-rotor (two-stage). Equipped with two main rotors working synchronously. Economical, effectively "push" the air to the drain pipe by increasing the pressure in the circuit of the evacuated device;
- Water ring. They are able to remove both air and liquid equally well. The disadvantages of such devices are significant energy consumption and the need for water.
Of the above types of vacuum pumps, only in the low vacuum range (105-102 Pa) only liquid ring devices work. For other types, the vacuum range is wider and reaches 10-3 Pa, i.e. degree of high evacuation.
Types of high vacuum pumps:
- Diffusion Highly efficient, provide fast evacuation. But they cannot be used for the refrigeration circuit, because the working fluid of these pumps is synthetic oils that pollute the evacuated circuit;
- Cryogenic. Their work is accompanied by the injection of nitrogen, which freezes and removes gases and liquids while increasing the degree of rarefaction of the internal atmosphere of the circuit;
- Ionic getter. Equipped with a thin titanium film that traps molecules of gases and liquids removed from the refrigeration circuit during vacuum. The most effective - eliminate up to 97% of impurities.
Despite the advantages of ion-getter evacuators, which turn off the provision of a high degree of vacuum (over 10-5 Pa), when installing split systems, they are rarely used - these devices are expensive.
What is the best evacuator to choose?
The choice of the optimal type of vacuum pump depends on the length of the freon line and the power of the air conditioner that needs vacuum cleaning from atmospheric gases. It is also necessary to take into account the dimensions of the pumping device, since it will need to be placed near the external split-block to connect to the vacuum procedure.
This device is capable of evacuating the circuits of refrigerators, car air conditioners and low-power split systems. For climatic equipment with a capacity of 9000 BTU and above, such a vacuum unit is not suitable.
A significant criterion is the residual (lowest) pressure reached by the vacuum pump in no-load mode (inlet closed). The lower the residual pressure (indicated by the manufacturer in Pa, mbar or microns), the better the vacuum unit.
The next criterion is the capacity of the vacuum pump (indicated in l / h). It determines the volume of gas pumped by the device per hour of operation at a given outlet pressure.
The last critical criterion is the power of the electric motor of the vacuum unit (indicated in W). The longer the freon line, i.e. the farther apart the split-blocks of the air conditioner are located, the longer it will take to perform vacuum cleaning of the refrigeration circuit. This means that a vacuumator with a sufficiently powerful engine is required.
Among vacuum pumps, this type gives the deepest vacuum. If dehumidification and de-aeration of a multi-meter copper line is required, for example, for VRV and VRF systems, this particular vacuum unit is required. However, specialists must work with it, the device is too powerful
Most often, split system installers use two-stage and single-plate vacuum pumps. The former are considered semi-professional and vacuum household air conditioning systems well, and the latter - the cheapest, although they do not provide enough quality for vacuuming freon circuits longer than 3.5 m.
Homemade vacuum pump
The evacuator can be made on the basis of a compressor from an old refrigerator ("Saratov", "ZIL", etc.). It is necessary to drain the mineral oil from it, replacing it with kerosene with a preliminary flush with a more viscous machine oil (summer "synthetics").
It is possible to make a vacuum pump based on a compressor from a refrigerator, only it is not capable of evacuating splits more powerful than 5000 BTU. Most of these homemade products (see. photo) are not vacuum equipment, but air compressors
In operation, the compressor will actively eject "mineral water" through the outlet pipe, quickly filling the oil trap. Replacing "synthetics" will make it possible to do without a separate receiver with a filter. But the installation of an oil trap is required. To control the degree of vacuum, you will need a vacuum gauge or at least a pressure gauge.
However, if a good air compressor can be assembled with a refrigerator compressor, then the evacuator will turn out to be rather weak, low-vacuum. Such compressors cannot provide a vacuum of more than 104 Pa, i.e. they are not suitable for vacuumizing split systems.
Conclusions and useful video on the topic
The procedure for evacuating the freon circuit of the split system:
Overview of different types of vacuum pumps, their capabilities and applications:
Comparison of the efficiency of a vacuum pump from a compressor from a refrigerator with a two-stage compressor:
When installing a split system, it is impossible to do without vacuuming the circuit, since such an air conditioner will not show reliable long-term operation.
However, it is unprofitable to specifically purchase a vacuum pump with a manometric station, even for the installation of two or three home split systems. It is more rational to rent these devices. Or, nevertheless, call the masters, after making sure that they have the necessary equipment.
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