The Heat Exchanger is very simple but effective: It is a 30m long drain coil buried in the ground through which air gets sucked into the fish room. For this I have two fan’s installed; one is the extraction fan in a top corner of the fish room. This one discharges old, humid air to the outside. Since the fish room is nearly 100% air tight it will create an under pressure and air starts flowing through the drain coil inside the room. To boost the system I installed another fan in a box that sits above the drain coil inside the fish room. This fan sucks air through the drain coil and helps the other fan with the workload.
The theory behind the whole system is that in summer the earth is cooler than the air temperature most of the time. So the air cools down while traveling through the pipe which helps cooling down the entire fish room.
In winter the temperature underground is warmer than the air temperature so the air is a little bit warmer when it enters the fish room after flowing through the pipe which helps with the heating.
Performance wise it brings the temperature down about 3 degree Celsius in summer and up 1 degree Celsius in winter.
All the wiring is done by myself. I advise you not to do it yourself. Water and power don’t go together very well and it’s a good way to get yourself killed!
On the front panel all you can see is the temperature controller that decides if the heater gets switched on or if the fans for cooling need to come on. On top of that I have a digital time switch that starts up the fans every so often regardless if it is to warm or not. That way I keep the air inside the room fresh and discharge stale, humid air to the outside. Also there is a humidity controller that switches on a little dehumidifier in case the humidity gets too high. On a really bad day in winter with rain or mist outside I extract 500ml of water that way. During summer the dehumidifier never comes on. Further there is a digital thermometer and humidity unit that records the minimum and maximum values so I get a better idea what is happening over a 24h period. The lights are getting simply switched on and off by a digital time switch. And last there are three small digital thermometers that tell me the water temperatures for the tanks in all three rows.