I like to put my eggs in 12 oz. deli-cups. They prevent the eggs from rolling should the incubator be jarred during incubation but still allow for adequate humidity and air flow. I cut clear rubber mesh to fit in the bottom of the deli-cups. It serves to lift the eggs slightly off the bottom of the cup in order to ward off potential condensation problems and, to a lesser extent, helps promote healthy air flow.

Igloo 120 quart marine cooler

   In my later designs, I built an air exchange manifold with an inline fan in order to move air from the bottom of the incubator to the top (or vise versa depending on what turned out to be most successful). I chose 40mm 12V brushless CPU fans for the job. The fans run quietly and with very little vibration. The fans are wired directly to a 12V transformer. I built the fan housing from a 1½" PVC coupling and two ¾"-1½" flush reducing bushings. I milled 40mm X 20mm holes in the 1½" coupling for motor placement with a spiral cutting bit and a Dremel. The idea and design were partially effective. The manifold was successful at moving air, but it became clear that moving air along the vertical gradient was doing little to solve my temperature variance problem. I tried a multitude of configurations but none resulted in exceptional results. Some configurations were somewhat stable and probably could have worked successfully, but I didn't want to take the chance. 

   I started with the 32" wire coated rack as a base. I built a frame out of ¾" PVC that fit beneath the wire rack. The heating cable was wrapped around the PVC frame so that it was distributed evenly along the length of the frame. The wire rack prevented the heat cable from being damaged. On the wire rack sit (3) 6 quart 12" x 10" x 4" stainless steel pans filled with water. The stainless steel serves to conduct heat more effectively for even heating and the water served two purposes... to help humidify the incubator, and provide thermal mass to aid in temperature stability.

   One of the things about traditional artificial incubation that's always bothered me is gas exchange. Incubating eggs are metabolizing stored energy and releasing waste gases. Most traditional egg incubation strategies focus on maintaining ideal temperatures and humidity and little attention seems to concentrate on fresh air exchange. On an experimental basis I opted to include some form of fresh air introduction into my incubator designs. For this purpose I opted to use an aquarium air pump (Rena Air model 100). In my early designs the air line ran into the intake manifold where the fresh air mixed with warm internal air before being blown back into the incubator through the exhaust portion of the manifold. Since the manifold proved to be only marginally effective in the testing phase, I reevaluated and bettered my design. I ultimately ran the air line into the center stainless steel water tray and attached an air stone to it. In addition to providing fresh air, the design helped boost the humidity the last several often difficult to achieve percentage points to total saturation.

  The egg boxes sit on styrene egg crate positioned atop a PVC frame that separates it from the stainless steel water pans. It's important that there's a separation between the boxes and the water in order to aid in air flow beneath the egg boxes and to eliminate the presence of hot spots in the incubator. On the underside of the egg crate are fastened two 12V 40mm X 40mm X 20mm CPU fans. I zip tie them to the egg crate and position them to create air flow parallel to the egg crate's surface. They each move approximately 7 cubic feet of air per minute and between the two of them, manage to completely homogenize the air in the incubator... in regard to both temperature and humidity.

   It's important to note that I built this incubator with the intent of using it with a consistent temperature regimen. Because I was anticipating a number of clutches within a narrow timeframe, it wasn't particularly feasible for me to use the 1-5-1, 30.5°C- 31.5°C- 30.0°C regimen. The difference in incubator configuration between the two techniques can be dramatic. A uniform temperature regimen requires consistent ambient incubator air temperatures and the 1-5-1 regimen requires consistent egg surface temperatures. Therefore, the placement of the probe is CRITICAL to achieving an effective incubator. In my final cooler incubator design, the proportional thermostat probe is placed in the airspace underneath the egg boxes where it can sample the fan-mixed air. If the probe is placed inside the egg box (insulated from the ambient air in the incubator), disaster can result. A probe interior to an egg box will send a message to the thermostat to continue providing power to the heat source even after the target temperature is reached inside the incubator. When that happens, the inside of the incubator continues to heat until the egg box reaches the ideal temperature. At that time, the thermostat decreases power to the heating element. Unfortunately, air in the incubator will have already surpassed the target temperature and will continue to heat the egg box until equilibrium is reached. A cyclical increase and decrease in temperature will occur until final equilibrium occurs. My tests indicated that this can mean surpassing ideal temperatures by as much as 4°F and the initiation of a fluctuation cycle that can last as long as two hours after the incubator is closed. In the scenario where the probe is exterior to the egg box, the thermostat decreases power to the heater when the ambient air in the incubator reaches target. The thermostat maintains that temperature and the egg box gradually reaches target, and once equilibrium is reached, the system maintains perfectly.

   I am continuing to test ideas that build upon the design that has thus far been my most successful. Space limitations have kept me from being able to utilize the domed covers in an effective design but work continues... I'll post any effective developments as they occur.

Mounted Fan

Mounted Fan