Homemade Incubator Advice Please

[thechickonthehill]

Since many of you seem to have a good bit of experience designing home made incubators, I wonder if you would give me your opinion on mine. I have used this incubator for three hatches now and I think I need to do some tweaking on the design to get a more consistent temp throughout the incubation chamber . I have about a 75 - 80 % hatch rate but would like to try to improve that.

Here are pics:

One end has two light bulbs for the heat source - one light stays on all the time and one is turned on and off with the thermostat. There is a center divider with a fan in the middle of this divider that pulls air from the heat box into the incubation chamber. The divider does not run all the way to the bottom of the box. It stops about a half inch from the bottom leaving a gap between it and the floor of the box. There are two holes in the light box end about the size of a dime. These are located towards the top of the box. There are 6 pencil sized holes in the end of the incubation chamber that are located at the bottom of the box. The temp closer to the divider is much warmer than the temp at the other end of the box. I am thinking I can at least somewhat fix this by making the divider a double wall with insulation in the middle. Right now, I cannot use the entire incubation chamber as there is too much difference in the temp from one end to the other. Right now, I put the eggs in cartons against the farthest end. I can go 2 carton widths from that end with only about .5 degrees variance in temp. (farthest is 99.5 and closest to divider is 100). The temps stay very consistent in each spot - they just get progressively higher the closer the thermometer is to the fan and divider. I'm trying to figure out what would work best to get a more consistent temp throughout the incubation chamber so that I can use more of the space (i.e. incubate more eggs at once). Should I use a stronger fan? Should I change the placement of the fan? Any suggestions would be appreciated.

Thanks,

Patty

 

[harris farm]

from what ive learned so far the fan is the key. i found that the fan works best on one side opposite the thermostat so the air moves in a circle around the incubator. 75 to 80% is a good rate. my last hatch was friday it was bourbon red turkey eggs and 8 out of 10 hatched and on time. hopes this helps.

 

[thechickonthehill]

Quote:
So moving the fan to one side of the divider as opposed to the center might actually work better to even out the temp?

 

[rebelcowboysnb]

How big is the gap under the divider an which way is the fan blowing?

I think having vents on one end an heat on the other is the issue. I think having all the vents on the wall of the heat chamber would help. 2 or 3 high on the wall an 2 or 3 low on the wall about the size you have now.

 

[thechickonthehill]

Quote:
The gap under the divider is about 1/2". The fan blows onto the eggs from the heat chamber.

I noticed that I made a mistake in my description too. The vents on the wall of the heat chamber are at the bottom, one on each side.

 

[rebelcowboysnb]

You could try reversing the fan an see what that does. Or you could try using a piece of pipe to duct the fans air across the incubator. But I'm pretty sure the issue is the 6 vents on the egg side of the incubator. That would keep that side cooler.

 

[abritton77]

Ive built 3 and I always have a fan blowing across the bulbs onto the eggs. All of mine have been cabinet style that I put a false back in that forces air all the way to the bottom. Ive not been able to get perfect temperature consistency.. my last bator is like a sportsman and my bottom rack stays about 1 deg low. I just set it up where the top rack is about .5 high and the bottom .5 low. I could probably do better if I turned my fan up, but it vibrates a little and I am worried that it may cause problem. Also I belive any thing over a 80% hatch rate is luck. I normally get about 80% on my eggs. Shipped eggs are very low.

 

[thechickonthehill]

Thanks for the input everyone. I will definitely try plugging the vents that are in the incubation chamber. I am also going to try putting in a double walled divider to hopefully help keep that area from being so much hotter than the rest of the chamber. My hatch percentage is just from using one area of the incubation chamber. I haven't been brave enough to try to fill up the incubator with the big temp differences. And the whole point of building this incubator was to be able to incubate more eggs at once so I want to do all I can to even out the temps before I try to hatch any more.

 

[tigercreek]

A couple of ideas to kick around - can you get a small register to direct the air in a wider pattern, spread the fan discharge out over more to the sides? How about reversing the air flow so it goes across the bulbs, down a double wall that has small holes drilled in it to allow some air into the egg chamber before it makes the turn at the bottom? I would start with no holes and check for cooler spots in several areas, then drill progressively larger holes in those cooler places untill the temps acrosss the bator evened out. ..........stan