Tall Homemade Cabinet Style Incubator Heat/Fan Question

[Three Cedars Silkies]

75 watt top and 60 watt bottom.

 

[muddstopper]

Quote:
My heat strip is connected directly to my thermostat. This type heat strip is actually a special nichrome wire, which looks like a long spring and has to be sized according to the amount of heat you wish to make. Sizeing is done by lenght and diameter of wire and resistance to electrical flow. The coil must be stretched so that none of the coils are touching each other, otherwise resistance will be reduced. You measure the resistance using an Ohm meter. I have found that 60-80 ohms will produce about 250watts of heat. The longer the wire, the more resistance it will provide, the less electrical current it will use, and the less amount of heat it will generate. If your heat coil was turning red, I suspect the lenght or diameter of the wire was either to small or short, or you could of had the coils touching each other, thus reduceing resistance and creating to much heat. Coils touching each other reduces the amount of wire the electrical current has to flow thru and results in less resistance to electrical flow and an increase in the amount of heat generated.

Air flow in my incubator is evenly distributed from side to side and top to bottom unlike the method used in the sportsman or dickey style incubators. Those companies direct all the hot air thru a gap between the top shelf and the door pannel. The air then is pulled down toward the bottom of the cabinet and up along the backside of the back wall to return to the fan. I have found that their incubator designs will always have a cool spot at or near the top back of the tray area. I can only suspect the cool spot is caused by the rotateing air flow which will trap any cool air in the upper back area of the cabinet. One would think that since the cabinet is closed that the temps would evenually stabilize all thru the cabinet, but as the air is forced along the glassed door area, ( and the 1/2inch thick uninsulated outside walls),the glass is colder than the air being circulated and cold air is pulled off of the glass door and walls and must be mixed with the warm air. Since the fan is always on and the heat strip cycles on and off, this results in uneven heating and mixing of the cold and warm air, and explains where the cold air inside the incubator comes from. Anyways, thats my theory and I'm sticking to it.

 

[muddstopper]

Cabinet hatcher with pull out drawers, built by Cbiblis

 

[gumbii]

doesn't it make more sense for the heating element to be on the bottom with a fan blowing up...? since hot air rises...? or is there a reason why all of the bators have the heater on top...?

anyways... i agree with the false back...

 

[shelleyd2008]

Quote:
What are you planning to use for the heat? If you are using a bulb of some kind I would point it towards the front with a fan blowing up if at the top, or down if at the bottom. You don't want the fan blowing on the eggs.

A friend uses the repti temp 500r thermostat to regulate heat in his homemade cabinet bator, this is what I plan to use in mine as well.
http://www.reptilesupply.com/product.php?products_id=75

 

[SED]

From my understanding you want the heat to be blown back down and since heat rises it causes a nice heated circulation therefore making the heat more uniform.

 

[SED]

The turners from my LG are 15"x15"

 

[shelleyd2008]

Quote:
Many I've seen have heat elements on the top and bottom to hold a steady temp better.

 

[aprophet]

Quote:
So the eggs do not get "cooked"

 

[muddstopper]

I feel that the heat source, whether its a light bulb or nichrome wire, or other, should always have some sort of divide between the heat source and the eggs. Otherwise even with a fan, you will probably experience some sort of radiant heat on the eggs closest to the heat source.

the heater in the top design has been around for a very long time and has worked verywell. I am sure that if the heater in the bottom was a better method, GQF or Dickey would have made the necessary design change by now. My way of thinking is that hot air rises and if the heat source is placed at the bottom of the incubator, with or without a fan blowing the air upward, that you will see a temp increase at the top of the incubator cabinet over what is measured at the bottom of the cabinet. With the heat originating at the top and being blow toward the bottom, this should minimize the heat rising and maintain a better distribution of the heat. It seems simple to me, but maybe I am missing something. I did take a heatgun and measure the temp of my wood heater and found that the fire is located at the bottom of the heater, but the top and sides where almost 100*F hotter than the bottom where the wood was actually burning. Seeing as the wood and fire are my heat source, the stove would be the cabinet, and the temps hotter on top than bottom, thats pruf enough for me.