Building Incubator/Humidity Questions/Air Circ

[NoSkiveez]

Im sorry, I have a lot of questions. I just dont want to goof anything up. Im building a homemade incubator and have been looking at alot of the photos of home built incubators here. Im using an old mini bar type fridge and I think it has a pretty good air tight seal on it. Its about 36 inches tall and 24 inches deep and 24 inches wide. It has a glass front door. I am going to use a light to heat the incubator and mount it at the bottom of the fridge. I have a few questions and thought I would ask before I spend money on something I might not need.

Humidity Questions
When it comes to increasing humidity, how would that be done? Do you just ad an extra dish of water to your incubator or add more water to the existing dish? Ive noticed that many incubators have sponges in the water containers, how does this benefit humidity? Is the type of sponge important or a preference? Ive also noticed on alot of photos there are canning jars with lids (and holes in the lids) on them with water in those, what is the function? Do you heat the water in any of the containers? I was considering using a fish tank water heater to heat water if needed, would that be acceptable? When room tempature eggs are added to the incubator will it change the humidity or tempature of the incubator? Will humidity level increases change the air temp?

Air Circulation
Ive also purchased a fan for the incubator to move air. Is it more ideal to have the fan at the bottom (where the light is) blowing air upwards or to have it at the top blowing air towards the light? I am pretty sure the seal on the door is air tight. How many air holes is ideal and is there a optimal place for putting these holes?


Thanks in advance!

 

[Daidohead]

The more damp surface area you have exposed to the air, the higher your humidity will be. The sponges are just an easy way to increase the surface area. damp towels, more bowls of water will do the same thing.

I place fans so that they blow on the heat source and distribute the warm air evenly over the hatching area. This also keeps the heat source from getting too hot.

In a incubator it is important to have vent holes at the high and low points in the incubator. cool air is drawn in down low and the warm air vents out of the top as heated air rises. This effect is lessened when useing a fan.

 

[Penturner]

I am in the process of building an incubator as well. and I will start with what I have learned so far.
Temperature control has been the hardest thing to get down so far. mainly getting the thermostat to respond fast enough to not have a big temperature swing. thermostat close to the light is the trick. I also recommend you get humidity in the neighborhood you want it when getting the temp set.
As for humidity. test your Humidity meter so you know how much it is off first. Yes it is off so find out by how much. In case you have not seen it somewhere else. put 1/2 salt with 1/4 cup water in it (salt is damp) in a baggy set the meter in the bag but not in contact with the wet salt. let it set for several hours. the Humidity in that bag is 75% no matter what you meter says. if you meter says anything other than 75% it is off by that amount. so any reading has to have that mount added or subtracted from it.
I live in a very dry climate and only had to put a pill bottle of water in my incubator to get it between 40 and 50%. opening the Incubator wipes out the humidity instantly and it does take a bit to get it back up, but not to bad. adding a small plastic container will bump it well above 60% so it is a bit of a touchy thing to get down. I am trying out different containers so I will have an idea of what to put in when.
As for heating the water I just set it close to the light and that keeps it warm.
The sponges and stuff people add increases the surface area of water that is exposed to air. Humidity increases from surface area not volume of water. you may or may not need it. I suspect people that live in humid climates actually have more trouble increasing it than I do because their air already has more water in it.
as for the incubator changing when eggs are added. I expect everything about the incubator to change with the addition of eggs. since part of the incubation includes the eggs loosing water, they will effect the humidity.
Air circulation is good and most incubators I have seen places them high so that they move the warmer rising air back down where the eggs are. So far my incubator is still air but I do not plan to keep it that way. With still air it will be 100 degrees 1 inch from the bulb but just 3 inches further away it is only 94 degrees. I don't see how anyone hatches eggs with still air

I am not sure about how many holes for ventilation but I do see most people place at least two low on one side of the incubator and two up high on the other side, the idea is to get the fresh air to have to pass through the incubator so fresh air gets spread around. My plans do not include any vents int he incubator itself but I am going to try and introduce fresh air from a separate space that warms and humidifies it before it is blown in the space with the eggs.