Reduced operating efficiency refrigeration chamber is often associated with degradation of the internal filling of the walls. When thermal insulation loses its properties, the compressor begins to wear out, trying to compensate for the constant flow of heat from the outside. This not only increases energy bills, but also shortens the service life of the entire cooling system.
Restoring the barrier is a complex process that requires complete disassembly of the housing and precise adjustment of materials. Unlike conventional household appliances, sealing and the absence of voids are critical here. The wrong choice of insulation can lead to the formation of condensation inside the walls, which will cause corrosion and mold.
This guide will help you understand the “sandwich” structure of a household refrigerator and safely carry out replacement. We will look at modern materials that can be used instead of factory ones, and their installation technologies.
Signs and causes of destruction of the insulating layer
The first and most obvious signal of problems with thermal insulation is the appearance of moisture on the outer walls of the case. This effect, known as the "crying refrigerator", occurs when the dew point moves closer to the external surface due to the increased thermal conductivity of the walls. If you notice that the side panels have become wet or sticky, then the destruction process has already begun.
Another symptom is an uncharacteristically long operation of the compressor or its almost continuous hum. The unit tries to maintain the set temperature, but the cold escapes through a layer that has become thin or saturated with moisture. In older models, physical settling or delamination of polyurethane foam often occurs, which creates voids - cold bridges.
⚠️ Attention: If the refrigerator body is swollen or deformed, this may indicate a critical accumulation of moisture inside the walls, which expands when freezing. It is dangerous to operate such a device.
The reasons for degradation can be different: from manufacturing defects when pouring foam to mechanical damage or water entering the housing through a leaky door seal. Temperature changes also have a negative impact when transporting the device in a lying position without proper exposure before turning it on.
Selection of suitable materials for restoration
Factory insulation is most often hard polyurethane foam, which is poured into the space between the internal and external contours. When doing repairs yourself, it is difficult to recreate a monolithic layer of the same density, so you have to look for alternatives. The main requirement for the material is a low coefficient of thermal conductivity and moisture resistance.
One of the popular options is slabs made of extruded polystyrene foam (XPS). This material has a closed cell structure, does not absorb water and holds its shape perfectly. However, its thickness may be excessive for a narrow gap, so it is often necessary to combine it with thinner insulators.
You can also consider liquid insulation, such as aerogel v in the form of paint or special two-component foams with a low coefficient of expansion. It is important to avoid using conventional high-expansion polyurethane foam, as it can deform the inner plastic box when it hardens.
Necessary tools and workplace preparation
To carry out work to replace the insulation, you will need to completely dismantle the refrigerator. You will need an assortment of screwdrivers, including Phillips and flat-head screwdrivers, as well as spatulas of varying widths. A construction knife with a supply of blades will not be amiss, since old materials will have to be cut very carefully.
Be sure to prepare personal protective equipment. Old insulation may contain microscopic dust that irritates the respiratory tract, and new materials emit unpleasant odors when cut. You should work in a well-ventilated area, away from sources of open flame.
The following is a list of basic equipment that you need to have on hand before starting disassembly:
- 🛠️ A set of screwdrivers and a screwdriver for removing fasteners.
- ✂️ Sharp scissors and construction knife for cutting materials.
- 🧤 Gloves, respirator and safety glasses for the safety of the master.
- 🧹 Vacuum cleaner for removing old crumbs and dust from cavities.
Pay special attention to organizing the space. The refrigerator body becomes very fragile after removing the outer metal, so prepare a soft covering on the floor so as not to damage the internal plastic container when removing it.
Technology for dismantling and cleaning cavities
The process begins with removing all hanging elements: doors, shelves, drawers and decorative trims. Then the back panel, where the compressor is usually located, is unscrewed and the top cover is removed. In some models refrigerators the outer metal casing is secured with latches, which must be bent very carefully so as not to break the plastic.
After removing the outer casing, access to the insulating layer will open. If it is polyurethane foam, you will have to pick it out by hand. Old material often crumbles or flakes off in chunks. The main task is to clean the cavities down to the metal without damaging the evaporator tubes, which can be mounted into the walls or glued to the inner box.
☑️ Preparing to replace the insulation
Cleaning should be perfect. Any remnants of old foam, grease or dust will impair the adhesion of the new material. Use a vacuum cleaner with a narrow attachment and then wipe the surfaces with a dry cloth. If there are traces of rust on the metal, they must be cleaned and treated with a rust converter before installing new insulation.
⚠️ Attention: When cleaning, be extremely careful with the copper pipes of the cooling system. Their damage will lead to a refrigerant leak and will require expensive repairs from professionals.
Comparison of the characteristics of insulating materials
The choice of material directly affects the energy efficiency of the restored device. Not all insulation works equally well in conditions of low temperatures and high humidity. Below is a comparative table of the main options that can be used for replacement.
| Material | Coefficient. thermal conductivity (W/m K) | Moisture resistance | Installation complexity |
|---|---|---|---|
| Polyurethane foam (hard) | 0.022 - 0.028 | High | High (requires special equipment) |
| Extruded polystyrene foam | 0.028 - 0.034 | Very high | Medium (cutting and gluing) |
| Mineral wool | 0.035 - 0.045 | Low (hygroscopic) | Low |
| Foil penofol | 0.037 - 0.040 | High | Low (as an addition) |
As can be seen from the table, mineral wool is the least suitable option due to its ability to absorb moisture. Once wet, it completely loses its heat-insulating properties and promotes corrosion. The optimal choice for a home craftsman is a combination of slabs XPS and a foil layer.
Liquid insulation is good because it fills all the voids, but their application requires skill. If you decide to use two-component foam, make sure that it is marked “for refrigeration equipment” or has a low coefficient of expansion.
Installation of a new layer and assembly of the structure
Laying of new material begins with careful measurement of all planes. The insulation sheets are cut with a small margin of 2-3 mm to ensure a tight fit without gaps. The joints between the sheets must be glued with aluminum tape or special glue for polystyrene foam.
If you are using a multilayer structure, first lay the main thick layer, and then a reflective screen made of foam foil inside the chamber. This will create a thermos effect. It is important not to squeeze the evaporator tubes too hard so as not to disrupt the circulation of the refrigerant.
The nuances of working with evaporator tubes
The tubes are often glued to the inner plastic box. When dismantling old insulation, they can be accidentally torn off. If this happens, the tube must be carefully glued back onto hot melt adhesive or aluminum tape, ensuring maximum contact with the plastic to remove the cold.
After laying the insulation, reassembly is performed. The outer casing is put on the frame and fixed. At this stage, it is important to check that the wires and tubes are not pinched. All fasteners must be tightened to the end, but without fanaticism, so as not to push through thin metal.
Checking tightness and first start-up
After complete assembly of the refrigerator cannot be plugged into the network right away. Let it stand upright for at least 4-6 hours. This is necessary so that the oil in the compressor flows into the crankcase, especially if the unit is tilted during operation.
It is better to make the first start without loading with products. Set the temperature to medium and listen to the compressor. It should not run continuously for more than 20-30 minutes without stopping (cycling depends on the model, but long-term operation without shutting off is a bad sign). Check the outer walls: they should remain dry and warm (or at room temperature).
If condensation does not appear during the day of operation, and the temperature in the chamber is stable, the replacement can be considered successful. Regularly check the condition of the door seal, since after disassembly the geometry of the opening may have changed slightly, and the rubber may not fit as tightly as before.
Is it possible to use regular polyurethane foam to fill voids?
Using regular household foam is highly not recommended. It has a high coefficient of secondary expansion, which can lead to deformation of the internal plastic box of the refrigerator. In addition, the structure of ordinary foam is more open and it absorbs moisture more strongly compared to specialized materials.
What to do if, after assembly, the doors no longer close tightly?
This is a common problem when replacing insulation, if the new layer is thicker than the factory one. Try loosening the hinges and moving the door a little. If this does not help, you may have to cut off part of the internal insulation in the area of the hinges or replace the sealing rubber with a more elastic one.
How much will energy consumption increase after replacing the insulation?
With high-quality work done and the use of modern materials (XPS, penofol), energy consumption should decrease or remain at the level factory indicators. If mistakes were made and cold bridges remained, energy consumption could increase by 15-20% due to more frequent switching on of the compressor.
Is old polyurethane foam dangerous to health?
Corked polyurethane foam is inert and safe. However, when it is mechanically destroyed and picked out, fine dust is formed, which can irritate the mucous membranes and lungs. Therefore, working with a respirator and goggles is a mandatory safety requirement during dismantling.