Bator was 160 degrees yesterday!!


11 Years
Dec 26, 2008
Port Angeles, WA
I am so bummed when I woke up my bator was 160 degrees!!
I use a reptile t-stat and it must have gone out in the night. I had over 70 eggs that I had paid over $100 for! GRR! The ones that were due to hatch on Friday were leaking what looked like puss, the 30 silky eggs I just put in on Sat were soft boiled.
Now I want a way to make this not happen again. I have heard of alarms. But what if you are not home? What if I bought two t-stats and plugged one into the other as a fail safe? Anyone have other ideas??
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Puting 2 thermostats in series with both set the same will offer some over temperature protection. You may expect though that the average temperature may drop a little as both thermostats will need to kick on before heater will turn on.

Other trouble is although having two thermostats cuts the chance of an over temp condition in half it doubles the chance of an under temp failure as if either of the thermostats fail open you lose heat. Low temp is likely the lesser of two evils though.

Just a thought on your incubator, if it was able to reach 160f it means it is operating an a low duty cycle with long periods of element off time and short periods of intense heat. Set up like this the heater might be off 70% or more of the time and on 30% or less of the time. If the thermostat fails closed it can quickly overheat, also the on and off cycling is going to be frequent, causing temperatur fluctuations and a more uneven heat.

A light dimmer switch can be added to the circuit to cut some of the power. With less power availible to the element it may be possible to fine tune it such that the element is on 90-95% of the time and off only 5-10%. In this way there will be fewer temperature cycles and the temperature spikes caused by the element cycling will be less abrupt with less overshoot and less radiated heat energy so the eggs can stay a more constant temp. I am not sure if you are using a bulb or element to heat with but if it is run cooler for longer your temperature wil stay more constant as it heats the air slowly and creates less radiated heat that can heat the eggs unevenly.

Given that thermostats are typicall electro-mechanical devices and like all electro-mechanical things have a finite life. Reducing the number of times the unit needs to cycle and reducing the curent the device needs to pass will reduce the chance of the thermostat failing.

Adding a dimmer is one more potential problem though as it makes the whole unit more complex allowing for human error to sneak in, but I think it is managable by securing the dimmer so that it can't be accidently adjusted and cause insufficient heating. Also some care needs to be taken to ensure that if the surrounding air temperature drops say at night when the house cools off the dimmer still allows enough power to the element to keep temperature without hitting 100% duty cycle where the unit won't be able to hold 99.5 even running the element constantly.
If you add the second thermostat at a higher temp it shouldn't be cycling on an off unless the first one fails so it should not fail. Also because the first one is the only one cycling it is the only one likely to fail in the off position.

They need to be set to different temperatures. One at 99.5 an the other kicking off right at 103.
oh my and i thought my 120 spike was bad?? i did have a few survivors.

how many bulbs do you have in there for it too get that bad? even with my 2 40w on full not dimmered i still only just got 120 and that was cause the fan cut out.

Why not add the water heater thermostat i am using one at the minute there isnt any technical stuff to fail on them its all metal it heats up shrinks and turns off the circuit. Do some testing tho as mine is near the bulb so its set to go off at 55 this is where people are getting confused but the heat within 2" of the bulb is sooo much hotter than the bottom heat so you will have to do some testing as to where to put it to work in worst case scenario. you just wire it into your live. in the uk we have brown blue yel/gree so for us its added to the brown. I find it ok the closer the bulb the less swing in temp. but in your case you could just set it to stop at 103 which could be on the dial something like 60.

I have tried to put it lower and set it too 38 but for some reason the circulated air doesnt turn it off even though my thermostat starts at 20 upto 90c it only works in direct lamp heat therefore having to be set higher. if i set it to 38 where it is now the top of the egg temp would be around 80

i have got it down to the best being 98 - 102 with a little help from the dimmer i am annoyed as i panic when it gets too hot and mess with dimmer and end up with lower temps. so now i just leave it be.

lots of messing but it would be worth it! what a shame.
Thank you all for the suggestions. I do like to keep things as simple as possible. So I would be more likely to go with the reptile t-stat again with another as back-up, or a water heater t-stat as back-up. I had one of those in my old bator. This one is a homemade cabinet style bator with 2-150 W bulbs in it and two fans. Here are the plans; .

Clay Valley, what you say about the more the on and off with the t-stat the quicker it dies makes sense to me. This bator is so well insulated that it would only come on about 1 time per half hour and it would only stay on for 1 minute! I am not that electrically minded, so I didn't think of that. I could probably just put in lower watt bulbs. I think that would be simpler than a dimmer for me.

Have you all heard of the alarms, or do you think the backup t-stat is enough?
I could probably just put in lower watt bulbs.

Yep good idea, I didn't think of that but was not sure if you were working with bulbs or a heating element.

The more "on" time you can get to keep temperature the better, think of a broody she is on the eggs nearly all the time and is just off for short bits.

More smaller bulbs is better than one big one, one burns out you still have heat and given they are spaced out in the incubator the heat will be more even one egg to the next.​
I'm so sorry I really do feel your pain, I lost over 140 eggs about 2 months ago when the cabinet went over 140 degrees. I got physically ill from the experience. Much lost $ and much loss baby chicken, turkey and guinea income .....I have trhe cabinet in semi retirement until we install a thermostat and a baky up in it...Nancy

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