Do eggs create their own heat?

[Scales Zoo]

If you read my fridge incubator thread you will know I had a problem with a difference in temperature between the top and bottom rubbermaid. (the bottom one was warmer)

The HCS unit had fixed the problem (by adding more heat to the top tub), but I had not planned to keep it there permanantly.

So, I have been experimenting, and have done almost everything I can think of to fix my problem with the bottom tub being warmer.

I then looked at both tubs and wondered what was different between the 2 (other than placement) - and why would the bottom one be warmer (I beleive I fixed any radiant heat problems I might have had)

Then I realized, there are 26 eggs in the one container, and 14 in the other. When I open the tub with 26 eggs, the obvious warmer air rushes out.

I remember discussing something about eggs with others in the past. The protein changes and metabolic processes going on in the eggs create some heat. I also think I remember reading something about this and it's effects on maternal incubation with Pythons and in gravid snakes.

So, do you think tha the 26 burm eggs in a tall rubbermade tub actually increase the temp in there to be 1.5 F over other temperatures in the incubator (and other tub). I've only got 2 very small holes in the tub.

Roy? Jeff? Anyone? What do you think?

Ryan

[Tim_Cranwill]

I would say that almost everything gives off heat/energy. I heard that in an experiment, scientists tried to achieve absolute zero and they found that even the table would give off heat.

In the case of a "living growing" egg, I would say that is would expel energy in the form of heat, be it 0.01F or a whole degree.

But what do I know? :D

[BoidKeeper]

According to the incubation section in the Complete Chondro they do. I'll find the exact spot after the game and post what he says about that.
Cheers,
Trevor

[chamitch]

yea everthing living gives off heat. even if its just little change in chemical compisitions it releases heat. so i woudl expect the closer to hatching the more heat will be put off. (think of compost or brewign home brew)

[Scales Zoo]

Originally posted by BoidKeeper
According to the incubation section in the Complete Chondro they do.

Actually, just got of the phone with someone who told me that GTP eggs have been shown to give off heat.

I'd love to read what it says, that is one book I don't have that I want to get in the future (probably after we get GTP's haha)

Ryan

[Scales Zoo]

And another thing I thought about, is like Chamitch said, the amount of heat given off would be likely to change through developement. I will have to watch the temps in the tubs.

People who incubate in large aquariums with open tubs would not notice it, but for us who have been using closed tubs inside a set incubator - the temperature in the egg containers might vary, and change throughout incubation.

I am designing an aquarium water heated incubator for python eggs as we speak, with open tops and egg crate grating. (I don't have a large aquarium, so I will likely build and seal something that will fit my tubs or styro fish boxes). In the last few weeks I've talked to quite a few people who now only use this method for python eggs, and are finding it works much better than their older methods.

Ryan

[JDouglas]

Interesting thread Ryan. I was wondering the same thing when incubating my IJCP eggs becuase i ran my incubator for months at 88.0F without any fluctuations. After putting the eggs in the temp went up 0.4 degrees in the egg chamber. Another thing I noticed is that a dead rotting egg releases quite a bit of heat. I had one egg decompose and the thrmometer probe was close to it. According to the thermometer probe it raised the temp in the egg box about 1.1F. After removing the very unpleasant egg the temp went back down.

[Scales Zoo]

Yes Jaremy, now that you mention it I think I've heard about the rotten egg thing before, but had forgotten.

I hope I don't get to experience that first hand with any eggs in this clutch.

[crocdoc]

eggs do give off metabolic heat. I ran my incubator for several weeks before adding eggs and the temperature went up after I did. The conditions were the same prior to the eggs being added, down to the same egg boxes with perlite, water etc)

[Jeff_Favelle]

If the incubator is on a thermostat, how can the temperature go up?

Yes, eggs give off heat, but if the incubator is on a thermostat, then the heat given off by the heater will just be lessened. Won't it?

[Tim_Cranwill]

Yes, but the question was "Do eggs create their own heat?".

You would only hope that your temperature controlling device would make the appropriate adjustments.

[Scales Zoo]

Originally posted by Jeff_Favelle
If the incubator is on a thermostat, how can the temperature go up?


Jeff, the incubator's thermostat is in the incubator (old fridge), not in the rubbermaids (with a lid and only 2 small holes). It controls the heat inside the incubator, which was pre-set at 89.5.

Since I have these eggs set up as I do, I notice the 26 big burm eggs giving off heat, because the temp in that rubbermaid is higher (up to 90.7, have since lowered the temp in the incubator to lower that temp) The temp in the egg box maintained 91 while we were at Calgary, while the temp in the incubator was holding at 89 (I had lowered it a bit, because the temp in the egg box was higher)

With smaller eggs I might not have noticed it. There are 26 big burm eggs in a fairly sealed tall rubbermaid. Burm eggs are huge!

If I had the rubbermaid in a water bath incubator (like I will next time - building one now) - I'd have more holes in the side of the rubbermades (and egg crates and water), and might not have noticed it, as the extra temps would have seeped out of the holes in the rubbermaids, and into the incubator - where, like you said, it would compensate and not raise temps.

Ryan

[crocdoc]

Jeff, the thermostat probe isn't in with the eggs, it's in the centre of the incubator, so it makes adjustments only when the whole incubator increases in temperature.

I had thermometer probes in each of the egg containers and next to the thermostat probes. At the same thermostat setting, the temperature in the egg boxes went up after eggs were added.

The misunderstanding is my fault, as I wasn't specific enough when I said that the temperature had gone up, as I meant in the egg boxes, rather than the whole incubator

[crocdoc]

haha, Ryan, you must have posted at exactly the same time I did, but pipped me to the post (excuse the pun)! Now it looks like I just repeated what you said, but typed it all down in a minute.

[Scales Zoo]

1 minute before!

You kept it shorter but said the same thing - I added more boring detail, to explain it to poor Jeffrey.

Ryan

[Stockwell]

Well, this is all interesting.
Its all news to me.
Eggs producing their own heat...?? Maybe, I really don't know. Certainly decomposition produces heat, as does fermentation, but normal developing ectotherms producing heat.. Maybe, I've never investigated that before, and can't say I've noticed any such effect in my years of incubation.

The only comments I can make involves the thermodynamics and instrumentation.
To start with, most thermometers are not accurate, so extreme care must be taken to utilize the same thermometer in all experiments. I assume this is being done, but even battery voltage will effect the reading on all electronic thermometers.
I discovered that several years back.
I have a big collection of thermometers,and tend to collect them, and most indoor/ outdoor probe type read higher as the battery gets weaker. This can vary by almost 2 degrees F.Somewhat opposite to what one might think.
Lab grade spirit or mercury thermometers(non electronic) can be used for all tests but also have intrinsic problems, primarily that they have too much mass to respond quickly.
Another consideration is that adding eggs to an egg box, compeletely changes the thermal dynamics of the box, because of the increased mass.
All incubators will have heat up and cool down curves,(think of a temp vs time graph) which is based on the differential of the thermostat, and the BTU output of the heat source vs the outside ambient loss factor.
Most thermometers won't accurately reflect the heat up and cool down curve, because the response time of the thermometers will be different than that of the air in the controlled space.
Adding mass to any system has the effect of dampening and averaging the extremes.
Depending on the overshoot and differential of the system, the egg mass might read higher than the same box full of air if the air temp spikes after T stat turns off due to the overshoot effect(heat still being emited after switch off)
If this spike is rather quick but high, it may not have been detected by the thermometer in the initial tests with a bare box. The egg mass however will tend to increase to the mean of the curve, creating the appearance of the eggs adding heat.
But are they creating their own heat, or simply storing part of the overshoot that was previously unmeasurable with thermal response time of the measuring instrument.??

This hypothesis of eggs producing internal heat should be easy to confirm.
I suggest someone take some measurements of an empty egg box fully loaded with moist egg media over a period of days.
Then simply fill the space with chicken eggs, known to be dead but approximating the mass of a live egg clutch.
See if your reading goes up!!
If it does, the phenomenon has nothing to due with life in the shell, but is an artifact of the measurement instrumentation and thermal response time(and changes in rates of evaporation)

[Stockwell]

Another comment about water bath , open water and even moist vermiculite in incubation systems.

Systems with a water component introduce another variable in addition to the considerations above.
Water, or water laden egg media will cool surroundings as evaporation takes place. This process is known as the "latent heat of evaporation" and is well known to anyone with fish tanks.
Any glass ,tank or vessel of water where evaporation is taking place will always be cooler than the surrounding air. (This is also why overheated snakes will sit in water bowls)
In the process of incubator design, I have discovered that moist egg boxes with holes, are cooler than the surrounding air in the incubator, but as the egg box dries out, the temperature goes up. This increase in temp isn't due to life in the eggs, but is more a factor of less evaporation taking place as the egg media loses water. The degree of change has to do with the rate of evaporation but is generally around a degree F.
So you should also consider that eggs placed on or over a water laden media will restrict air flow, thus reduce evaporation, and that reduced rate of evaporation, might be reflected in an increase in egg temp, but such an increase should never excede the peak air temp of the system.
So when talking about egg temps varying by a mere degree or so, there are lots of considerations before concluding that the eggs themselves are generating their own internal heat.

[Scales Zoo]

Good post Roy. Thank you.

First off. I'm not sure the brand of my thermometers with probes(will check tommorrow), but they are very accurate to each other. I've put them together and measured the exact same temps. I've also switched them between egg boxes, and with in 2 minutes, each is reading exactly what the other was just previously. Yes, you were right, I did confirm this (your proud of me aren't ya!).

And I am quite sure I took care of any over shoot, radiant, or latent heat issues that might have been inherent. I insulated the bottom tub, and my fan circulates the air in the incubator very quickly. The heat doesn't come on very often, or for very long, and the "always on" fan (which I added in conjunction to the turbo fan that comes on during heating) is pointed to take heat away from the element while it is running and after it shuts off

I think I should switch the rubbermades around(from top to bottom), and see if this effects any difference. It would rule out any of the above mentioned variables, I think.

I've been reading more, and it does seem as though python eggs do generate heat during development. Monitor lizards produce heat during digestion, chicken eggs create heat during development, and the GTP guys have mentioned eggs creating heat. I do have a strong gut feeling that this is what is happening with my burm eggs - I will continue testing to try and disprove that - you know how I am.

Science is great kids!

Ryan

[Stockwell]

Ryan, why not try my chicken egg test, using identical containers and identical moist substrate. I really think rates of evaporation could have a huge bearing on the outcome of experiments. And are you temps actually higher than your highest peak air temperature? A box full of eggs, restricts evaporation by covering the air exchange to the substrate.
Certainly if there is anything to this theory of eggs producing their own heat, there should be a marked difference in the outcome of tests with a box of python eggs, vs a box of dead chicken eggs, in identical setups, with identically prepared substrates.

[crocdoc]

Roy, Ryan and I haven't actually come up with the idea that eggs give off metabolic heat, it has been recorded before by others.

However, I do have a comment regarding this statement: "If this spike is rather quick but high, it may not have been detected by the thermometer in the initial tests with a bare box. The egg mass however will tend to increase to the mean of the curve, creating the appearance of the eggs adding heat."

I would find it odd that the thermal inertia of the thermometer's sensor would be great enough that a temperature spike would not be detected, yet the temperature spike would be enough to increase the temperature of eggs (which have a much greater thermal inertia).

I should also add that I noticed the difference with five well spaced monitor eggs in a 7 litre egg box, so I'd find it hard to imagine the reduction in evaporation making that much of a difference.

[chamitch]

stockwell did point out some good points but i dont think it explains it all.

even though snakes are considered cold blood, this is not tottaly true. when there is energy involved ie digestion and use of the protien, fat for energy. there is heat emited from the chemical reactions in that procces.

also think about that even plants produce some heat. i belive thats how they bust narcotics being grown in a feild.

so using this idea the changes in chemical make up in a egg would indeed give off heat. yes it needs heat from the incubator to start the reaction but after that more heat can be produced from the changing of aminos and all the other goodies inside.

oh how i love science
peace

[Jeff_Favelle]

Ahhhh that makes sense. I could see the temps rising then. I'm sure of it. Especially during the last 2 weeks of incubation. With biggie-sized Burm eggs, that would definitely be something to watch for.

Maybe more holes would be good, as then there would be more lee-way with the air from the incubator getting in, and the "heated" egg-air being able to escape.

Let us know how it goes.

[Aug]

Don't mean to bud in. I just want to help out.

From what i know, eggs should produce heat. In fact "cold blooded" organisms do as well. The fundamental biochemistry of all organisms throughout evolution has almost remained constant-especially lipid and carbohydrate metabolisms to say the least.

In embryogenesis, there are tones and tones of cell migrations, that require the expenditure of transcient, highly energetic molecues, such as ATP, UTP, GTP etc. All organisms are not 100% efficient in transfering/coupling this molecular energy into mechanical motion or other processes. Even then many cytoskeletal elements (IE, actin and microtubulin) breakdown the energy molecules to create cell dynamics.

It get's pretty nasty from there. But trust me, every organism gives off heat. it's a matter of how much heat.

With you current setup you may want to check the thermodynamics like stockwell mentioned, as it may play a greater role in uneven heat distribution. However, there are many variables when considering 1 degree.

Just my 2 cents.
Augustin

[Scales Zoo]

Originally posted by Stockwell
Ryan, why not try my chicken egg test, using identical containers and identical moist substrate.

I will.

And are you temps actually higher than your highest peak air temperature?[B/]

Absolutely. The heat doesn't come on that often, I've got a fan that really blows the air around and keeps things even. The thermometers move at .1 F - and will do it in 10 seconds if the temp rises that much. I've measured the temps in the incubator, and when they are doing the 88.0 - 88.3 thing - the one egg box is at 90.5, the other one is at 88.6. I have full trust in these thermometers, they've been with me a while and I've really tested them out, - they record a low and high setting so I can check how things have been while I was away.


[B]
Certainly if there is anything to this theory of eggs producing their own heat, there should be a marked difference in the outcome of tests with a box of python eggs, vs a box of dead chicken eggs, in identical setups, with identically prepared substrates.

I've got a box full of chicken eggs, I'll put them on verm and in a tub - and get back to you.

Ryan

[Jeff_Favelle]

Hmmmmm......Roy, I think maybe I'd have to agree with you. And your posts totally re-confirms my love for my no-substrate water incubators!! Heat the water which heats the air! There are no spikes in temperatures because the water is a HUGE buffer of heat. Small heater, LARGE water source = NO over-shooting in heat! Woo-hoo!

[Scales Zoo]

Originally posted by Aug


In embryogenesis, there are tones and tones of cell migrations, that require the expenditure of transcient, highly energetic molecues, such as ATP, UTP, GTP etc.

Releasing ATP, creating heat - that's it!

Now I remember who I was talking to about this. Thank you for refreshing my memory!

Ryan

[Scales Zoo]

Originally posted by Jeff_Favelle
Hmmmmm......Roy, I think maybe I'd have to agree with you. And your posts totally re-confirms my love for my no-substrate water incubators!! Heat the water which heats the air!

I'm doing this next as well. I like the principals behind it (100% humidity and no wet verm touching bottom eggs)

There are no spikes in temperatures because the water is a HUGE buffer of heat. Small heater, LARGE water source = NO over-shooting in heat! Woo-hoo!

I am using a heat source from a small hovabator in a large fridge, with an extra fan. The water and verm and eggs must weight over 30 lbs. The heat source does not come on often at all, and when it does, the fans blow any warm air away. I do not beleive my heat source is too much for my capacity (2 Large water sources and egg masses)

But yeah, agreed, water and an accurate fish heater (with a non vertically orientated incubator like this fridge) would definitely keep steady temps.

Ryan

[Jeff_Favelle]

And Ryan, on top of the fish heater, you can have a Helix as a back up. Set the fish heater to have the incubator at 89.5F, and then set the Helix to 90F. DOUBLE protection! The incubator would be fooool proof, provided the power didn't go out! :D

Cheers.

[crocdoc]

haha... I had the power go out in my neighbourhood a month or so ago, on our first cool night of autumn. Any other night before or after that one night wouldn't have been an issue. Whenever I rang the electricity company's emergency information line, I got a recorded message that was upgraded on the hour. When I rang at 8pm, the message said the problem would be sorted by 9pm. When I rang at 9:10, the message said 10pm. When I rang at 10:10... well, you know where this is heading.

At 11pm I was contemplating the idea of lifting the whole incubator into my truck and driving it to my office, to plug in there. The temperature of the incubator was dropping at roughly .5C/hour, so by the time the power switched back on near midnight the temperature hadn't dropped enough to worry about. It's likely the eggs inside the egg boxes didn't experience much of a drop at all.

[Scales Zoo]

Jeff, what heat source do you use with the helix as back up protection?

Croc Doc - In Canada most of our hot water heaters are run with natural gas, so we could just fill warm 2 litre pop bottles (do you have pop in Australia, or just beer - hehe) with warm water and put them in the incubator to keep temps stable during a power outage.

Ryan

[Stockwell]

Back in my Ball Python days I used to run an inverter for my closet of incubators. It automatically switches over to battery power if the hydro goes out.
This is only really necessary for guys with expensive python eggs, but even computer UPS systems can be worth the expense if you're hatching high end stuff, although most UPS' wont last long enough without some good size extra gel cells, which are quite expensive.

I once had a 7 hr power failure in the dead of winter.. That was scary..
I moved all the herps to the bathroom, and put wet towels under the doors, and ran the gas heated hot water into the tub via the shower.
The bathtub acted like a heat reservoir, and filling it via the shower was quite effective at quickly warming the air.
Every hour or so, I would partially drain the tub, and run the shower again.
The house got down into the 40's but I managed to keep the bathroom in the 70's.

If the hot water approach wasn't successful, I was prepared to bag up all the snakes and put them in the car.
I also was prepared to run my furnace gas valve transformer off my incubator backup, connected to my car battery in the driveway.
I wouldn't have had enough current to run the blower, but I could convection heat the house without the blower. It would help quite a bit. It happened accidentaly once, when my blower seized. It was several days before I noticed the blower wasn't running. All the duct tape adhesive had melted and the duct tape was all on the basement floor. Thats also when I discoverd my furnace had been incorrectl wired. There was high heat limit switch, but it didn't even have wires attached

[crocdoc]

Ryan, some people have gas, some electricity. My hot water system runs on electricity. I have been thinking, though, of putting in some sort of sealed water containers for thermal stability.

Stockwell, I have considered getting an inverter. I have a feeling that a single cool night may not kill these monitor eggs, though, for they are a local species and even the termite mounds in which they are laid tend to have drops in winter at night.

[Jeff_Favelle]

I use an expensive aquarium fish heater. Then, on top of that, its plugged into a socket that is wired into the Helix. The Helix has never had to work, as its set for 90F and the incubator stays between 89.1F and 89.6F.

[Scales Zoo]

Just a follow up to the saga.

I went to check the eggs today, and the fridge door was open! The eggs got down to about 83, they are back at 89 now.

Also emailed Dave Barker, and he read this thread and he said most people don't realize it, but python eggs do create heat - he is sure of this. More heat during the latter part of incubation as a rule, but he's measured temperature differences of 11 F from the inside of a burm egg mass, to the outside - and said it was responsible for loss of clutches in closed and small egg containers. Dave also said that if my eggs are creating heat now, early on, it may be an indication of not enough humidity. I will definitely be watching it.

This thread has been great, many other good things were brought up that is good to think about. I am definitely building an aquarium heater incubator for future python eggs, and will do the eggs on grating over water in secondary containment fashion. I may even move these eggs to that style of incubator, and use the fridge for colubrids.

Thanks Roy, Jeff and others for all your input.

Ryan

[Jeff_Favelle]

Great stuff! :D

[JDouglas]

Another source of heat in a power outage would be a gas stove/oven. If your kitchen is not too large the oven could be turned on with the oven door left open. Or, water could be boiled and dumped into a bathtub every hour or so as crocdoc explained.

[crocdoc]

um, that's great, Jaremy, but how do I turn on the stove/oven if it is on electricity, too? :)

If my stove was on gas, the power outage wouldn't have been an issue.

[JDouglas]

Ya you would need a gas oven ~ LOL! In my house everything is gas except for the fan for the furnace.

[MouseKilla]

Fascinating stuff! I have to admit that some of it was over my head with my limited experience with incubation let alone thermal dynamics so I'm afraid I don't have much to contribute.

What I'm wondering though is how important 1 degree really is. Is that amount of difference or fluctuation actually going to effect your hatch rate?

As I said, I can't speak from experience here but it seems to me that eggs of any kind couldn't possibly be that sensitive or very few would survive in the wild. Am I wrong to assume that it would be next to impossible for a gravid snake to find such a well insulated place to deposit her eggs?

Another question I have is why is it that it seems python breeders are so much more concerned with precise incubation temperatures while it is commonly said that corn snake eggs can be successfully incubated at temperatures anywhere from 70 - 90F? Are python eggs that much more sensitive or just worth that much more money?

[crocdoc]

MouseKilla, in the wild corn snakes are temperate to warm temperate animals and their eggs are abandoned by the mother once laid, so they are adapted for putting up with whatever variation they may encounter. Pythons are tropical to temperate animals, but in the wild the mother controls the temperature and humidity to a certain extent by wrapping around the eggs and shivering. Their eggs aren't adapted for as great a variation.

Of course, there is no doubt that it doesn't all come down to just sensitivity of the eggs. Even if python eggs weren't very sensitive (I can't say whether they are or are not, for I haven't bred them), I couldn't imagine people putting them in a shoebox on a closet shelf, shrugging and hoping for the best if the babies are going to be worth several hundred dollars each. :)

[Stockwell]

Mousekilla, in general plus or minus a degree F or even two is no big deal. I think there is frequently a quest for "perfection" simply to see if it's achievable, and there is a perception that the higher the stability the better the hatch rate. Whether or not that is true,is another question.
I might add that I have hatched Spotted/Childrens Pythons at 85F rather than the usual 88 to 90, typcial for most Pythons. I was breeding those in the 80's when few others were, and found it odd that they hatched in 45 days. I figured that means the temps are too high. So I hatched a clutch at 85, and they took a week longer to hatch, but were still pretty fast

And I have hatched Ball Pythons with fluctuations between 86 and 91F with 100% hatch rates
I'm not sure you'd get away with that with Chondro eggs, although I'm wondering if anyone has tried.
There's not a whole lot of motivation to "experiment" with thousand plus dollar hatchlings at stake. There is alot of follow the leader in this hobby. Once someone has success with a set of criteria, is generally considered gospel, and copied note for note by other breeders
I suspect our quest for the perfect rock stable incubator is more of a technical challenge then a necessity.

[MouseKilla]

Very interesting answers. I hadn't considered the tropical/temperate factor before and I had to slap myself in the forehead once I'd read it. It just makes sense that tropical species would be less tolerant of low temps and big fluctuations.

I had suspected that achieving and holding that magic temperature for your eggs was something that was more for the benefit of the owner of the eggs than the eggs themselves. Or as Roy said, "more of a technical challenge than a necessity".

Of course when I'm incubating my own eggs I'm also going to shoot for the same conditions that have been proven to work in the past. What else would someone do if the offspring is more important to them than finding out what the eggs could withstand?

I don't know if I'll ever bother with expensive gagetry myself, especially if I manage success using more basic methods. I figure if I can hatch, say several clutches of normal BP eggs by leaving them in a rubbermaid on a shelf in a heated room, why would I change how I do it if I later began working with expensive morphs rather than normals?

I think for some people the building of this stuff alone, that technical challenge, becomes a hobby in it's own right and that probably fuels the quest for "perfection" too.

[Stockwell]

Well for me certainly incubator design is a hobby.
I've been doing it for more than two decades.I enjoy the fabrication and design in addition to the carpentry and circuitry, plus electronics, circuit design and instrumentation is my profession.
I guess I'm lucky to have a career that also serves my hobby.
I'm already starting on my next new controller design, which includes a nice back lit LCD display, and a solid state temperature sensor rather than a thermistor.(National's LM35)
Why?? simply for fun,that quest for perfection, and so I don't need to turn on the light to read my incubators :)

[crocdoc]

I think your hobby should include making similar units that run on 240 volts, just for fun :)

Of course, since you wouldn't be able to use or test them there, you'd have to send them to someone else. Say, me for example. Yeah, that's the ticket, I'd test them for you. That's just the sort of guy I am.

[Stockwell]

LOL...Doc,You've doing alright on your own. I've seen pics of your unit and You also appear to be a "builder"
I see you've been using light bulbs as your heat source. Nothing wrong with that, other than the space they fill. There's not too many cheaper heat sources. My very first incubators used bulbs, then I switched to "Power resistors" which are smaller and never burn out. I'm currently using Flexwatt since it's cheap and has the added advantage of spreading the heat out. It also lasts forever.
The nichrome Hovabator heaters(elements) are also available as a spare part and I've used those but they aren't worth 25 bucks.
Hovabator wafer thermostats however are still the best darn deal around for a tight differential bi-metal Tstat that can switch line directly.
They are rated for 240 as well.

[Scales Zoo]

I love wafer thermostats!!!!

http://www.berryhill.on.ca/b-cart/Product.asp?pid=TS115

Ryan

[crocdoc]

Stockwell, I am very impressed with your professional looking incubators. I particularly like the inlaid panel for the thermostat (my thermostat sits on top of my incubator, sealed in a plastic box so that the dial can't be tampered with).

My main incubator issue is insulation, which is why I went for usijng an old refrigerator. My home has neither air conditioning or central heating, for the climate here is usually not extreme enough to require either (although if I worked at home during the day I'd opt for air conditioning). The temperature in my home therefore goes up and down with the outside temperatures, so a wooden incubator just wouldn't keep the eggs from experiencing fluctuations. As it is, I have to move the incubator into my garage during summer to avoid it overheating on those rare extremely hot days (a couple of days of 40-42C this year killed off friends' seasonal egg production, in one instance 120+ diamond python eggs), then back up to my apartment in autumn. In winter the temperature in my apartment may drop to 12C at night, but it's lower in the garage.

I chose bulbs for ease/speed of installation (got the incubator built just in time this past season, with a week or so spare to test it) and so I could tell instantly whether or not are doing their job. Space will certainly be an issue in that little bar fridge, though, so I may have to think about switching over to heat tape, too. I reckon that there may be a very narrow window of opportunity to get that done, between the last eggs from last season's last clutch hatching and the first clutch of the next season being laid, unless I set it all up in a separate incubator while this one is still full. I've picked a species with one of the longest incubation times of any reptile, so if they multiclutch late enough in the season the incubator will be full of the same female's eggs 24/7/365.