Build the air conditioning yourself

You know that German summer: Either 15° C and rain or roaring heat at 30° C upwards, on top of that thick sultriness. While the former is still tolerable for the organism, it may severely affect the second concentration, well-being and health. In particular, sleep and work spaces therefore require a functioning ventilation and cooling. We explain the principle of adiabatic cooling in this context. Without expensive compressors, without harmful climate agents can be so pleasant room conditions produce - we show you how to do it!

Adiabatic cooling: How does it work?

Everyone knows adiabatic cooling, since it is based on the principle of evaporative cooling based. Thus, the feeling of cold with moist skin, for example, when leaving the pool, significantly higher than dry skin - the heat of the body is dissipated faster.

You can do something like this with your own home. Already in antiquity, the Romans used fountains in the houses or damp cloths in front of the windows for air conditioning. Disadvantage of this "direct" adiabatic cooling is the strong increase in humidity in the interior - in our humid, thermally insulated and often airtight apartments impractical.

Modern adiabatic cooling systems operating on a passive principle therefore use heat exchangers. Like a car radiator, you exchange warm and cold air over water as the carrier medium. This keeps the air dry and the system closed.

Build the air conditioning yourself: cooling

Adiabatic cooling in the house

Build the air conditioning yourself: yourself

Functional principle of adiabatic cooling.

The following drawing describes the principle of a adiabatic cooling system for a family home, apartment or office. The system components can be bought in the hardware store or in the sanitary trade, also online many cheap shopping opportunities.

The principle of the system is quite simple: The warm air from the interior is sucked into the hydropneumatic humidifier. Its capillary action quickly humidifies the air and directs cool air into heat exchanger 1 (WT1). The cooled water from WT1 is pumped electrically in WT2. Through this, outside air is sucked in with the lower electric fan, which flows cooled into the interior.

Components for the adiabatic cooling system

  • 2 plate heat exchangers, 315 x 73 x 97 mm
  • 2 tube installation fans, Ø 100 mm
  • 1 universal aquarium pump, capacity 300 l / min
  • 1 aerosol humidifier (AirTec HydroOne, in specialized trade)
  • 4 1/2-inch hose fittings
  • 2 hose fittings for the pump
  • 100 cm water hose, 1/2-inch fitting
  • 1 plastic ventilation grille, 35 x 35 cm
  • approx. 150 cm plastic pipe white, Ø 100 mm
  • 1 two-way drain tap with 4 1/2 inch connections

Heat exchanger housing (made of stainless materials):

  • 2 steel strips: 95 x 8 x 1.8 mm
  • 4 steel cover: 32 x 16 x 1.8 mm
  • 40 M5 machine screws, 16 mm
  • 80 washers M6
  • 40 M6 nuts

Aerosol humidifier housing (made of stainless materials):

  • 1 sheet steel strip: 61 x 15 x 1.8 mm
  • 2 steel cover: 16 x 16 x 1.8 mm
  • 24 M5 machine screws, 16 mm
  • 48 washers M6
  • 24 M6 nuts


  • 2 screen printing plates: 55 x 30 x 1.2 cm
  • 2 screen printing plates: 37.6 x 30 x 1.2 cm
  • 1 screen printing plate: 55 x 40 x 1.2 cm
  • 18 wood screws, 3.0 x 50 mm
  • 2 wall-mounted steel angles with M8 bore, 40 x 40 x 2.0 mm
  • 2 machine screws M8, 30 mm
  • 2 washers M8
  • 2 wing nuts M8

Fresh air funnel:

  • thin plastic plate turned into a cone with bottom 10 and top 30 cm opening and fixed with hot glue
  • Grid, mesh size 3 mm, round, Ø 30 cm


  • jigsaw
  • Sheet steel hole saws: 100 mm and 20 mm
  • HSS drills: 6 mm and 10 mm
  • silicone gun
  • strong adhesive joint sealant (for example Sista Dicht & Fest by Henkel)
  • Kneadable and moldable, adhesive sealant (e.g., from the body shop)
  • building foam
  • Spray paint (also residues suitable)
  • Installation glue
  • (Electrical) Tacker
  • Possibly. Electric or inert gas welding device for welding the boxes instead of the screw connection.

Assembly of the heat exchanger and humidification tanks

Boxes for the two heat exchangers are first assembled from the pre-cut sheets: bend the long sheets on the folding bench first after 31, then after 15, then again after 31, again after 15 and then again 1 cm. That's how you get the Basic form. These are fixed by three screws on the narrow fold, which you must pre-drill with the 6 mm drill. Then the lids are folded over 1 cm, with 3 holes on the long sides and 2 on the narrow ones and for the time being one-sidedly bolted to the frame. The folds are sealed with sealant.

The same procedure is followed with the smaller container for holding the aerosol humidification device. Here you must pay particular attention to precision, since this container must be waterproof later. It is therefore best to check with water that the container is tight. If this is the case, spray the container out of the spray can with a thick layer of paint - this is also where a remainder may be used. You should not forget the already prepared lid.

Breakthroughs and ventilation pipes

Now it gets a bit painful: Two exactly superimposed, 10 cm wide openings in the wall must be made. The openings must be exactly 20 cm above each other. Then push two of the plastic tubes with a diameter of 10 cm through the openings. Leaks are sealed with construction foam. The pipes must project inside about 5 mm out of the wall.

Now drill the hose feedthroughs into the heat exchanger boxes at the bottom or top. They must correspond exactly to the distance of the connecting pieces at the boxes.

Now be centered through the backs of the two Heat exchanger boxes with the steel hole saw milled out two 100 mm holes and placed the two boxes centrally and horizontally across the pipes, so that the pipes protrude about one centimeter into the boxes. Then secure the boxes to the wall with two screws each. The pipe feedthrough is sealed inside the box with joint sealant. Now the heat exchanger elements can be used.

Pre-assembly of the housing and the humidifier

Directly screw the lower housing half of the screen printing plate directly above the bottom heat exchanger with two upward-pointing angles in the middle of the wall. She wears the humidifier. On the left side, 1 cm from the edge, however, you must first mill a 100 mm hole as a cable / hose leadthrough.

Now a 100 mm hole is cut through the lid of the lower heat exchanger box, as well as through the lid of the humidifier. The two holes must be precisely aligned, resting on the lower housing part. Between these two housings now a 90-mm plastic pipe section is inserted and sealed airtight with sealant. The humidifier is now mounted in the humidifier box; the humidifying nozzles point in the direction of the heat exchanger. Do not forget to mount two holes for the power cable and the water inlet hose directly underneath the cover and to seal them carefully after the cables have been laid.

Now you can already mount the two side housing halves and the cover.

Install vent

The pump is in, seen from the front, left Cold water line assembled. Connect the hoses so that the pump can be mounted to the wall with two screws. Then feed the cables down through and through the lead-through bushing of the bottom of the housing.

The overflow and bleeder valve is mounted in the right hose. It is attached to the top of the housing on the right (see drawing) and connected to the hoses. This allows the system to be vented at the highest point.

Final assembly: fan, air funnel and front of the housing

Before the upper heat exchanger, the inner tube fan is now mounted in a 15 cm long piece of pipe and led through the 100 mm bore of the upper heat exchanger box cover. The pipe is carefully glued with mounting adhesive - here should not wobble or leaking. The inner tube fan is mounted and the cable is carried to the bottom.

Now, a loose funnel of a total of only 11 cm deep, but with a rear opening of 10.5 cm and a front opening of about 30 cm is bent from the flexible plastic and fixed first with brackets, then with mounting adhesive in the funnel shape.

A hole with a diameter of 29 cm is now cut into the front of the housing, exactly 5 cm below the upper edge. On the back of the hole now the plastic net is clamped with tackers. It should rest undulating. The air funnel is then glued to the rear of the net with assembly adhesive - this connection should also be tight. Then the front housing plate is put on trial. The funnel should be "slipped over" the pipe feedthrough. If everything fits, the system can now go into operation!


Before commissioning, the system must be filled with water. For this purpose, the drain cock is opened and with a water hose connected to a tap. Then the water is turned on. After the water no longer flows into the system, the upper vent cock is opened. If a steady stream of water comes out of the system, it is free of air bubbles. Both stopcocks are now closed, the water hose connected to the humidifier port.

Now the humidifier, pump and fan are switched on. After a few minutes you will already feel a first, fresh breeze. Keep a cool head!

Safety and liability information

This system is expressly one DIY construction, i. e. It is built and put into operation on its own. We therefore decline any liability for function, breakdowns and any damage.

If you are unsure about performing the work, consult a specialist or specialist company. In particular, by using electricity and water in the same device, make sure that there is a functioning FI circuit in the fuse box - safe is safe.

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