The idea of turning old furniture into a functional cooling device sounds like a tempting DIY project for brewers, winemakers or those who want to save on the purchase of specialized equipment. However, before you start to modernization old furniture, you need to clearly understand the difference between a factory refrigerator and a homemade device. An ordinary kitchen cabinet or pencil case is not designed to work with humidity, temperature changes and vibrations that occur during compressor operation.
If your goal is to create a chamber for fermentation beer or wine, where a stable low temperature is required, then such a project is quite feasible if you have technical skills. Unlike household use, where tightness and food safety are important, technical cabinets allow you to experiment with thermal insulation and installation of equipment. It is important to understand that turning an ordinary wardrobe into a full-fledged refrigerator for storing food is almost impossible without completely replacing the internal lining.
In this article we will analyze the technical aspects of creating a cooling chamber, paying special attention to the choice of equipment and safety rules. A standard household compressor will not be able to effectively cool the volume of an uninsulated wooden cabinet due to the high heat loss of the material. Therefore, the first step is a sober assessment of the design and preparation for serious changes.
Assessment of the design and selection of housing
First The next step is to analyze what exactly we will redo. The ideal candidate is considered to be an old Soviet refrigerator, whose motor has failed, but the body has been preserved. Wooden cabinets, bedside tables or pencil cases require enormous insulation work. Wood is an excellent thermal insulator when dry, but it is hygroscopic and over time will begin to absorb condensation, which will lead to mold and rot.
If you decide to use a wooden case, you will have to completely insulate the internal volume. To do this, the internal space is sheathed with sheet metal (stainless steel or galvanized) or dense plastic, and a layer is laid between the cabinet wall and the inner lining. The thickness of the insulation must be at least 50 mm to achieve at least some results. expanded polystyrene or penofol. The thickness of the insulation must be at least 50 mm to achieve at least some results.
Pay attention to the door. It should fit snugly around the entire perimeter. Factory refrigerators use a magnetic seal embedded in plastic. Homemade designs often use separate magnetic tapes or even clamping mechanisms, which is inconvenient to use. Tightness is a key factor in energy efficiency.
⚠️ Attention: Using cabinets made of chipboard or MDF in conditions of high humidity (which will inevitably arise inside when the compressor is operating) will lead to swelling and destruction of the structure in one season.
It is also worth considering the dimensions. The condensing unit takes up space. If you build the system into an existing cabinet, part of the usable volume will be “eaten up” by the equipment and insulation. Plan in advance where it will be located evaporator and how to organize air circulation inside the chamber.
Selection of a refrigeration unit
The heart of your future device will be a refrigeration unit. For homemade projects, they most often use ready-made blocks from household refrigerators or special units for beer systems. A household compressor, for example, from Atlanta or Indesita, is quite powerful, but requires proper piping. It is important that the power of the compressor corresponds to the volume of the chamber.
There are also compressors of the type Danfoss (now Secop), which are often used in car refrigerators and small commercial installations. They are more compact and quieter, but may require a special electronic control unit. The choice depends on how quiet the device should operate and where it will be installed.
The thermostat is a critical element. Without it, the compressor will work continuously, freeze the contents and quickly fail. For brewing, controllers like EGO or more modern digital thermostats with a remote sensor are used. They allow you to set the exact temperature on and off, as well as the delta (temperature difference).
- 🧊 Compressor - choose a unit with a power reserve, since home-made insulation is worse than factory insulation.
- 🌡️ Thermoregulator - a mandatory element for controlling the climate inside cameras.
- 💨 Fan —necessary for mixing the air and eliminating zones with different temperatures.
- 🔌 Relay —protects the electronics from overloads when starting the engine.
When purchasing a used compressor, be sure to check its performance. It should start, operate without any knocking noises and heat up evenly. If the unit hums but does not start, the start relay may be faulty, which can be easily replaced.
Installation instructions and insulation
The process of re-equipping a cabinet requires consistent work. First you need to dismantle all the shelves, drawers and fittings that are not needed. The inner surface is cleaned and degreased. If the body is metal, it is advisable to treat it with an anti-corrosion compound.
The next stage is the creation of a “thermos”. The walls, bottom and ceiling are covered with sheets of extruded polystyrene foam. The joints between the sheets are carefully foamed with polyurethane foam to eliminate cold bridges. An internal lining is mounted on top of the insulation. It can be food-grade aluminum, plastic or moisture-resistant plywood coated with varnish.
The installation of the refrigeration unit is usually carried out in the lower part of the cabinet or outside it, if the design allows. The evaporator (refrigeration grill) is placed in the upper part of the chamber, since cold air is heavier than warm air and will fall down. However, for uniform cooling, a fan is needed that will drive air through the evaporator.
☑️ Installation stages
It is important to provide ventilation for the compressor itself. If you hide the engine compartment inside a cabinet, there should be an opening for cold air to come in and hot air to come out. Overheating of the compressor is a common cause of breakdowns of homemade refrigerators.
Electrical circuit and automation
Connecting electrical equipment is the most critical stage, requiring knowledge of the basics of electrical engineering. The standard connection diagram for a household compressor includes a starting and protective relay. However, to control the temperature, this circuit is broken by the thermostat. The phase wire from the network goes to the input of the thermostat, and from the output to the compressor.
For more advanced systems, especially in brewing, controllers with two relays are used: one for cooling, the second for heating (thermal mat). This allows not only cooling, but also maintaining a temperature above the ambient temperature, which is important for some types of fermentation. The connection diagram is usually printed on the controller body or in the instructions for module.
All connections must be made in junction boxes. Wires passing through a metal casing must be protected with rubber bushings to prevent vibration from wearing away the insulation. Be sure to use grounding as humidity inside the chamber increases the risk of electric shock.
| Component | Function | Installation location |
|---|---|---|
| Compressor | Compression refrigerant | Outside or in a ventilated compartment |
| Condenser | Heat dissipation | On the back wall (black grille) |
| Evaporator | Heat absorption | Inside the chamber, at the top |
| Thermostat | Temperature control | Outside, sensor inside |
Don't forget about protection against power surges. Compressors are sensitive to changes in the network, so turning on the device through a stabilizer or at least through a surge protector with protection will prolong its life.
Why is my compressor humming loudly?
The humming can be caused by an incorrect installation angle (the compressor must stand strictly vertically), wear of internal parts or resonance of the tubes. Try to carefully bend the copper tubes without breaking them so that they do not touch the housing.
Refrigerant charging and evacuation
This is the most difficult stage, which often becomes a stumbling block. If you use a ready-made unit from an old refrigerator, where the tubes are already sealed, then there is no problem. But if you are assembling the system from scratch or reversing the evaporator, you will need to charge it with freon. For this you need a pressure gauge station, a vacuum pump and scales.
Before refueling, the system must be evacuated. This removes air and, more importantly, moisture from the circuit. Moisture in the system freezes in the capillary tube, forming an ice plug, and reacts with the compressor oil to form acid, which corrodes the engine from the inside. The vacuuming time depends on the power of the pump, but is usually at least 15-20 minutes.
Refilling is done strictly by weight. The compressor nameplate or technical documentation indicates the amount of refrigerant (for example, 60 grams R134a). Overfilling or underfilling freon will lead to ineffective operation or breakdown of the compressor. After filling, the tubes are sealed.
⚠️ Attention: Work with refrigerants requires a license and special equipment. Self-refilling without soldering and vacuuming skills often leads to equipment damage and is hazardous to health.
If you do not have experience in soldering copper tubes and working with freon, consider using ready-made refrigeration modules that are already charged and only require installation in the housing.
Typical problems and their solutions
When operating a homemade refrigerator, you may encounter a number of difficulties. One of the most common is the formation of condensation on external walls or inside food. This indicates insufficient thermal insulation or lack of ventilation. The solution is to check the door for tightness and add a layer of insulation.
Another problem is that the compressor runs non-stop. This could mean a freon leak, a malfunctioning thermostat, or too much heat loss from the chamber. Check that the door closes tightly and listen for hissing where the pipes are soldered. Also make sure that the temperature sensor does not touch the metal walls of the evaporator.
Noise and vibration are often annoying if the refrigerator is located in a residential area. To reduce noise, the compressor can be installed on rubber gaskets or hung in a separate soundproof box. It is important not to block the access of air to the motor at the same time.
- ❄️ Ice build-up - a sign of moisture getting into the system or defrosting malfunction.
- 🔊 Knock when starting - wear of the piston group or problems with the start relay.
- 🌡️ Does not maintain temperature —check the door seal and fan operation.
Regular maintenance, including cleaning the condenser from dust and checking electrical contacts, will help avoid sudden breakdowns.
Frequently asked questions (FAQ)
Is it possible to use a regular cabinet without metal inner lining?
Technically it is possible, but it is highly not recommended. The wood will absorb moisture, swell, become moldy and begin to rot. A metal or plastic sealed bath inside is required for the durability of the structure.
Which compressor is the quietest?
Inverter-controlled compressors and Danfoss BD series units are considered the quietest. Conventional piston compressors from refrigerators are quite noisy, especially when starting up.
How much electricity will such a refrigerator consume?
Consumption depends on the quality of insulation and the volume of the chamber. Homemade designs are usually less efficient than factory ones and can consume 20-30% more energy due to heat loss through the walls.
Is it necessary to make a hole for air intake?
Yes, if the compressor is located inside a cabinet, it vitally needs an influx of cold air and removal of hot air. Without ventilation, the motor will overheat and burn out in a short time.