Please help with a homemade incubator--what am I doing wrong????


10 Years
Feb 27, 2009
Built an incubator today based on Miss Prissy's plans. Everything is wired correctly, the thermostat works except one thing--currently I am having 15 degree temp swings! The thermostat I am using is the cheap-o hot water heater thermostat I see everyone else using. I put it in an electrical box like many more recent posts have advised. I have a very nice three speed computer fan installed. I have tried with both a 20 watt and a 60 watt bulb now, with the same results. Please help!! I am so frustrated now I want to cry. Currently the thermostat is about 7 inches from the light source--will moving this change my results? Should I take it off of the metal electrical box and use the air temp? Is there an alternate thermostate I could use? Can somebody please tell me what else I can change without spending a ton more money--i have already put $60 into this project, which I really should have used to fix up our old hen house instead.
Help please from all you do-it-your-selfers out there!!!!
My Dh built ours, his advise is...

Thermostat needs to be on the end opposite of the bulb.
Make sure fan is fairly close to bulb.
We still had 8 degree temp swings and had a successful hatch.
We could not get away from the temp swings so for the next hatch we put in a Wafer thermostat, about $23 on line. It holds perfect temp, within a degree.
Hope this helps!
Im am playing with my first ever homemade bator I just made to track temps. My therestat is about 4 or 5 inches maybe from my 40W bulb. <my bator is one of those little styrapome coolers so 40 w is almost to much =P
First are you useing one two or three therms , next are you testing air temp or watter wiggler temp.
I have 1 therm 1 therm/humidity gauge combo in my bator all the time both glass therms, and untill tonight i was useing a medical digital therm for periodic testing of the water wiggler.
Acording to my 2 glass ones my bator gets up to 102 and 110 <they read diffrent> and one goes down to 80 and one goes down to 92 or so while my thermastat does its thing , acourding to my digital that i stuck in there off and on thru out the day my water wiggler temp went from 98.7-100 .
the diffrence there is huge and thats why I am asking about what youre useing and how.
ok, now that I have taken a break and calm downed, I can answer all of these questions. (Just imagined how frustrated I would be if I had eggs in my bator right now!?

First of all, what is a wafer thermostat and where would I find one?
Ok, answers:
I hadn't really thought to blame the thermometer. It is digital with and indoor and outdoor reading. I put the outdoor sensor in the water wiggler and the indoor reading is reading the air temp in the incubator. I can stick one of our fish tank thermometers in as well to confirm readings.

My cooler is a big igloo cooler--bigger than the standard walmart styrofoam coolers, so I think it needs more than a 25 watt (it took it forever to heat up with one). May need a 40, but I will have to pick one up tomorrow. Currently it has a 75 watt so I could watch the kick off more quickly.

As for the distance between thermostat and heat source--I too thought it should be far away, but found an old post by somebody saying it would tighten up the temp swings if you put it closer. So I am hoping some other people will pitich in on this.

Also still wondering about attaching the thermostat to an electrical box vs. the air temp. I just took mine out as an experiment to see if it works better that way.

Our fan is catty corner to our bulb, very close and blowing on it towards the thermostat.

The water wiggler temp is more stable, but currently cannot make it up above 98 degrees (even with air temp up to 110) due to the huge temp swings.

Thank you for the help.
More please?!
Im not shure how much more help I can be the only part I know much about at the moment is how annoying the therms can be =P so just check to make shure thats working correctly and maybe throw another one in for good mesure maybe.
Right now my water wiggle temp is going from 99-101 (been tweeking the thermastat and have a new digital thermometer with probe )

Good luck , you could do a search from incubator temps or some such while you wait for responses.

I ended up buying a wafer thermostat as well, but I think my biggest "improvement" was putting a dimmer on the bulb..
I was using a regular? sized cooler..but the dimmer allowed me to heat it up quick when I wanted it..Then to dim it when I was at the "right" temp, hence avoiding the big swings
I'm having the same problem with my water heater thermostat. Being a retired Navy Electrician( Jack of all trades and master of none).Normally a water heater thermostat sits against the side of water heater.After my current chicks and eggs in my bator. I thought about flipping around the thermostat to see if it works better.

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