Re: Incubator to Heat treat varroa mites
Aram, If I am understanding you correctly you are looking for a consistent temperature. The egg incubators I have made hold to within two degrees plus or minus. This is good enough for hatching eggs. I was able to get within half a degree plus or minus with some experimenting. Here is what I discovered about stabilizing the temperature when using a hot water heater thermostat. Still I think you will find they operate with small zones. At times I have found I could not get a thermostat to adjust to an exact tenth of a degree. it woudl be 95.8 or 95.2 but I could never get it to settle in between. I am not sure there is a mechanical thermostat that will not operate like this and each stat seems to be different. Again I am not sure just how exact you need your temperature to hold. Electronic heat sensors would be the next step up in exact control.
Place the thermostat above the heat source with the metal back facing the heat. By close I mean one to two inches. This will cause the light or heat to go off and on frequently but keep the temperature to a very tight range.
Better humidity control has been found by using a crock pot as a heat source by tobacco growers that need 120 degree temperatures and 70% humidity.
Do not over tinker when you first start up your incubator. the temperature is more like a weight swinging on a string. it takes a while for it to stop swinging. It will overshoot the mark then fall to below the mark then rise again. after several hours you can then test it's high and low.
Another trick to cause the thermostat to hold to a tighter temperature is to carve away the outer cover and expose the inner metal disk directly to the air temp. be careful and go slowly so that you do not damage the metal parts inside. I have two stats that I have carved out. one i damaged the other I didn't. it does improve it ability to hold a steady temp. Nothing I have found holds a perfect temp there will always be a high and low.
The addition of a fan is a must to get even temperature throughout a chamber. Even then it is not a perfect distribution. For this I would suggest more but smaller light bulbs placed around the chamber. the more the better. Keep in mind regardless of what is going on with the air temperature which is what the thermostat is reading. any object in the chamber tends to absorb that energy more evenly. An exception would be when all the heat is coming from one direction. Sort of like when you stand in the sun on a cold day. the sunny side of your body feels the warmth but the shady side does not. It is best to have any object in the chamber shielded from direct heat from a bulb and heated only by the warm air. this helps the object remain at a constant temperature throughout it's mass and not have a warm side and a cold side. Just be aware there is a difference in the temperature of the chamber and the air in it and the temperature of an abject in the chamber.
I use a "Bottle Lamp Kit" at Home Depot for mounting a light bulb. I mount this horizontally in a hole drilled in a 2X4. Then screw the thermostat at the end of the board so that it hangs over the bulb by an inch or two. The temperature marks on the thermostat is of no use. The thermostat is calibrated to measure approximate temperature of hot water through a sheet of metal, not direct air temperature. You will have to experiment to find where your desired temperature is. Being able to adjust temperature without opening the chamber is a big plus. On my 20 cf refrigerator design I can adjust the temperature from a hole drilled through the back of the housing. As you can imagine I went to greater lengths to make this design top notch. and it functions like I did also. I built about 4 incubators before attempting this one. It really is pretty simple and consists of two devices. a heat source and a control for that heat source. everything else is about a nice air tight, or nearly so, container and enough room. Small air leaks make it difficult to control humidity.
Keep us updated on how this treatment actually works, I find it very interesting.
Everything gets darker, as it goes to where there is less light. Darrel Tank (5PM drawing instructor)