Heating element on the bottom?

[millebantam]

I built my own and have the heating element and fan centered on the top, blowing down. I couldn't be more pleased with it. I have the temp sensor located in the center of the back wall of the unit. I have fantastic hatch rates and have tested for hot/cold spots in it, but with 4 different thermometers located in 4 different positions, the variance is less than one degree.

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[Akane]

There is likely a good reason all current incubators are made with top heating even if some older ones can function with bottom heat. I would think anything with a constant heat source, which was more common in the first incubator designs, would work to have it on the bottom. You have the same amount of heat always going up from the bottom and would just regulate that amount to change the temp instead of the time it was on. However in one that has a thermostat turning on and shutting off the heat to control temperature instead of changing the amount of heat produced I think you will run into temperature layering problems. When the thermostat goes off the heat sits at the top and the bottom cools. If we are forcing the heat down from the source it is always trying to go back up so we get lots of air movement. If the heat is coming from the bottom it already wants to go away from the heat element. You would have to run a lot more fans to move it around because just pointing one away from the heat source will only increase what it wants to do potentially making layering worse instead of better. Increasing air movement increases moisture lost from the eggs and drying of membranes during hatching. You will have to be more exact with the humidity and it may not work at all.

 

[Poulets De Cajun]

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Any chance you have cliff notes for this explanation? I'm lost...

 

[Poulets De Cajun]

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What kind of heating element is that?

 

[rebelcowboysnb]

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That does not add up. Puting the heater in the bottom does break up thermal layering. Not as much as you need it to but it helps. Thermal layering is as bad as it gets in a top heat still air incubator.

 

[Akane]

Talking about small bators is not going to be the same as talking about cabinets. Still airs are only very small bators and top or bottom heat probably doesn't matter. I've wondered about it and decided it's just easier for them to put the heat in the top and the water in the bottom. A still air is going to layer about the same no matter what you do because of it's size and location of vents. The air can't seperate anymore than it does. If you had a very big bator like a cabinet though it would make a difference. How often do you see still air bators larger than about 1 sq ft? The air has a lot farther to travel in a bigger bator and you could get a much bigger gradient. You'd also need a bigger fan to move the air and vents are not located the same. It's comparing apples and oranges.

 

[rebelcowboysnb]

Heat from the bottom no matter the size of the incubator or the amount of fans will help with thermal layering compared to heating from the top. Does it help enough to be worth the effort? Prabably not unless the incubator is over 2 feet tall. I do think changing the circulation padderns from "front to back" to "top to bottom" would help more on bigger bators but puting the heater in the bottom does help.

 

[millebantam]

The element/fan assembly came from Petiatric.com. They specialize in high end parrot/exotic bird brooding and incubator products. The heat element assembly is reasonably priced for the quality. I also have the solid state temp control unit from them, and it's pretty pricey, but is the best of the best. I have run this bator for 6 month stretches, through many different external temperature conditions, and my bator temp has never varied more than 1/2 a degree, if that. Scroll down the page of this link to see what they offer.
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What kind of heating element is that?

http://www.petiatric.com/parts.aspx

 

[AngieChick]

Thank you Christopher for bringing up this topic. I was actually considering switching my homemade cabinet bator from bottom heat to top when I fuss with it in a month or so. Hearing the arguments for and against has been very helpful.

 

[Poulets De Cajun]

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Thanks for the link! I already have a sizeable cooling fan from a computer server though, and GQF's heating element is 200 something watts for about $10 less. I wonder how they differ....