Wafer Thermostat? Stockwell/Scales Zoo

[JDouglas]

How accurate and consistant are wafer thermotats? I am considering using one in an incubator. +/- how many degrees?
How long will the wafer last?



Thanks,

Jaremy

[Will]

Not sure how long they last, but I had one in 3' x 2' x 2' incubator I built this year. I was insulated w/ 1/2" foam. It held the temp approx +/- 5F. I was aiming for 83, and it was between highs of 88 and lows of 80F. It only had one clutch of Cali eggs in there, but it was designed to hold 20+ King/Milk clutches, so there was a lot of empty air in there. I'm sure if I had more mass in there that held some of the heat, that might tighten it up and stabilize the spikes quite a bit more. It is only for my Kings and Milks, so it does a great job for that, not sure if that is tight enough control for Pythons or Boas though.

[JDouglas]

Thanks for the reply. I would be interested in seeing a pic or description of your incubator.

+/- 5F is definitley too much for me. My current incubator fluctuates +/- 0.2 F and has successfully incubated pythons but it only holds one clutch. This year I hope to have at least two clutches and needed a bigger incubator so I am building one. My first incubator was made in a $12 cooler and a larger version was not feasible due to high cost of a larger cooler($80). Well now I have spent more making this new incubator than the cost of the cooler and I am hoping it will be a success. I am building it very similar to Stockwell's incubator that he pictured awhile back but I am thinking of using a wafer thermostat mounted on the side like Scales Zoo did with his foam box incubator. I remember him having good luck this way and Stockwell has commented on wafers a few times. I was just looking for more info and specifics.

[Scales Zoo]

Wafers kick butt. You can get them from Berry Hill for like $28 cdn.

Our old hovabator controls very, very well - right now it is 81.4 - 81.6. Actually, 90% of the time it is at 81.5, but I have a high/low memory in my thermometer which shows how far it varies.

The incubator I built, is still away on loan. I remember it holding really well also. It is a little bigger than a hovabator, and uses the same 40 watt element (also available as a part at Berry Hill).

Actually, once I got the bugs worked out of things, I think the hovabator lid did a fine job in the fridge. Just turned the lid upside down, placed it on the bottom of the fridge, and used the racks to hold my egg containers.

But this year, I built my first aquarium heater incubator - and am amazed how well it holds temperature. I have yet to get a chance to use it on real eggs.

One problem with temperature fluctuations is the temp outside the eggbox dropping below the temp of the egg box, which causes saturation of the humidity in the egg boxes, and that causes condensation to form on the top of the egg box, and the sides. That is pulling moisture out of the air and vermiculite (or whatever you are using) and sometimes it causes drops on the eggs, which is a bad thing.

I've yet to build an incubator with a wafer thermostat that I wasn't pleased with - and the original frustrations I had with the fridge incubator weren't caused by the hovabator parts, but caused by the burmese eggs creating their own heat in the beginning and end of incubation.

Ryan

[Stockwell]

Wafer thermostats are fantastic, especially for the price. If you're an American you can buy directly from the manufacturer GFQ and they are dirt cheap.(12 bucks)
http://www.gqfmfg.com/p2.asp?login=&...&productid=389

The differential is actually very tight under 1/2 degree F.
People that have problems either have too big a heater or no fan circulation.
You need to remember that the total swing from high to low in any incubator design is not just the thermostat. Mechanical thermostats like the wafers have mass. The more the mass the longer the response time because air heats up and cools down much faster than the big hunk of metal on the T-stat.
A common error in many incubator designs is having too much wattage in the heater. Doing so pumps heat into the air faster than the T stat can respond to turn it off. This creates huge overshoots. Stirring the air with a small low wattage fan is a great advantage and speeds up thermal response times, and reduces the overall swing in tempertures.
A rough rule of thumb is you need 10 watts of heat for every cubic feet of air inside your incubator to raise the temp 20F over an ambient of 70F. 20F is what is required for Pythons incubating at 90 in a room with an ambient of 70F
So typical 2 or 3 cubic foot incubators should only consume about 30watts, and less if you only do colubrids.... I've seen people use over 60 watts then complain that the thermostat isn't tight enough... Whats really happening is you're heating the air faster than the thermostat can respond.. plus the oversized heater is still pumping out internal heat even after it's switched off. Reducing the wattage of the heater greatly avoids all these problems.
In addition to small circulation fans, adding mass in the space inside an incubator helps to prevent huge swings in temperature. This is why a good deep layer of vermiculite in your egg trays or even containers of water adds to the stability in incubators.

[JDouglas]

Thanks for the info guys. I did purchase a wafer thermostat and I am almost finished with the incubator. Its good to hear that the thermostat will work well.

The internal dimensions are 10 in H, by 18 in D, by 36 in L. I am using 3 pieces of 33 inch flexwatt for heat. This may be to much. I may take out one piece if neccesary. I am also using a lof cfm fan that you reccomended. The thermostat is mounted at one end at the same height as the eggs will rest. I will be using the "no substrate method" as I did in my other incubator. Each egg chamber will be completely sealed and have 1 3/4 in of water in the bottom with egg crate susspended over it. The front of the incubator will be sliding glass.

I also put water bottles over the entire floor of the incubator for a heat sink. The egg crate shelf is held up by the water bottles and the egg chambers are set on this shelf. The isn't much empty air space left in this incubator and that is a plus I think?

I will post a few pics to show you the finished product.

[Stockwell]

It should take 15 to 30 minutes to reach a setpoint of 90F and have the T-stat turn off. If you get there much sooner, you'll want to remove some heat tape as you'll surely be having overshoot and unnecessary high peaks.
The only potential problem with using just water under the egg crate, is the babies could drown. I use vermiculite, then just completely soak it. Its the same thing in regard to producing a saturated air space in a sealed container, but its safter for babies after they hatch and end up below the grate. I also don't like water sloshing around when I remove the containers.
I recently heard about a herper that thought he'd try the substrate-less system for his Leo eggs..
Of course it hatched the eggs but a couple hatchlings got under the grate and drowned in the water which is pretty silly.
Using a saturated media like vermiculite, perlite or even spaghnum moss will at least allow some locomotion so babies can get back out and up for air. Screening the grate is also possible but that makes it tougher to grab when you want to pull it out.
Here's some baby hogs that just hatched over a saturated vermiculite/perlite mix.
Not even out of the egg and they're under the grate

[Jeff_Favelle]

Good info Roy. +5!!

[Will]

I will eventually get around to posting pics of the incubator. I was pleased with the way it worked out, being my first attempt at doing it and all. It still hasn't been finished. I have to seal the insulation, and slap something over the insulation, and add a bottom to it.

Now that I read Roy's post, I may have added too much heat tape. The higher variances tended to be on the higher end of the spectrum(above 83) as opposed to below it. I might go back and time it, but I'm sure it goes above 90 in under 10 mins. I may take out some heat tape next year and see how that works. Again, there was ALOT of empty space in there which also doesn't aid in heat retention.

Considering all that I would say the thermostat worked well. That 5 degree fluctuation may have more to do with the incubator itself than the wafer.

The only thing that bugs me about it though is that the incubator is in an adjoining room to where we sleep(no door), and 'click, click, click' all night can drive you nuts sometimes...

EDIT:

In lieu of photos, I'll add a quick description of it since you asked. It's basically a 3x2x2 frame made out of 2x2" wood. There is 1/2" foam insulation board cut to fit in the frame. There is 5 or 6(I forget) strips of 4" heat tape on the bottom. An eggcrate platform 6" above the heat tape held up by screws and 1x4" wood. In the center of the 1x4" wood is a small fan(should I ever need it,). The clutches go in rubbermaid shoeboxes. It hold 3 boxes, 7 layers deep. Hope that gives an idea.

It took only a 3 or 4 days to build, by an unskilled workman(myself)... Can't remember what the final cost was, probably around $100 CDN(and about 40 was the fan, and 30 was the wafer...).

[JDouglas]

Well my incubator is finished as soon as my glass is cut to the right size. I have been using 1/4 foam board in place of glass to test it. I am very pleased with it's performance. With all the water bottles in the bottom it took a long time to get up to the correct temperature. It had to heat up twenty-four 20 ounce bottles and all the water in the egg chambers a well. Now that the water is heated up I can open the door for half an hour and let out all the warm air and it will warm up in 18 minutes. Once it is at its set point it runs for 3 minutes and turns off for 6 minutes. The room temp varies from 68F to 75F. The air temp in the incubator has a swing of +/- 0.25F and the egg chamber air temp is even less at +/- 0.20F.
I am having the same problem that Ryan is having with condensation. Their is too much condensation and dripping from the lid. I will try a few things but does anyone have suggestions on overcoming this.

I will post a few pics soon!

[JDouglas]

Here are a few pics...


The thermostat...


The low flow/watt fan...


Lots of water bottles...


The shelf and egg chambers are in...


Thermostat control & power light...


The power light is connected to the end of the last piece of heat tape so I know that all the tape is working when it is on.

[Stockwell]

That looks like a great job Jaremy....You'll soon be a thermodynamics expert...
Condensation will take place at the areas with the highest delta T. In most wooden incubators that is the front, as the doors will leak and have a poorer insulation value than the sides. With hovabators and removable top units the problem is usually the lid.

I think your boxes are too close to the top of the incubator and the egg container lid therefore, is probably cooler due to it's proximity to the underside of the top, causing lots of water to condense there because of the temp difference(delta T)
Using shorter containers or putting a layer of foam insulation or even a blanket over the top of the incubator will reduce the temperature difference between the ceiling and the egg box, and should reduce the amount of water on the lid.
When you have a 100% RH inside a sealed enclosure any difference in temp between the outside and inside of the container will result in water coming out of saturation and condensing on the cooler surface.
It's hard to keep all sides of eggs boxes at the same temp, so some condensation will always occur, however it's Ok when its the front or back of the containers, so those are the ends that should be closest to a wall.
Sometimes a couple small holes in the lid will also help prevent water build up but you will lose some water vapor through those holes, however it shouldn't be significant
Unless water is actually dripping on the eggs, there should be no problem.
Other more extreme measures such as having the trays on a tilt can be effective, but it has side effects like having the eggs roll.
Spaghnum, paper towel or other absorbing materials can be used to protect the eggs or to aborb any water on the lid. Gluing a thin layer of sponge or a J cloth to the lid might work... But try just insulating the top first, or using shorter containers.

[JDouglas]

Thanks for the conmpliment and advice Stockwell. I will cut a peice of foam insulation to the exact size of the top and see if that helps.

I learned a ton about building incubators form this forum and would like to thank Scales Zoo(Ryan), Stockwell, Jeff Favelle, Mykee, and Retic for their input. From reading past posts and following their advice anyone can build an incubator that will out perform high dollar incubators.

Thanks again,

Jaremy

[Jeff_Favelle]

That's totally what its all about Jar. I mean, why go through all the trials and tribulations and effort to get viable eggs, only to have a crappy incubator set up?

I might have to comission you to build one of those beauties for MY stuff!!!

[mykee]

Jaremy; beautiful incubator, hope it works well for you for years and years.
Roy; though your posts are chock-full of useful information, sometimes they hurt my brain (i.e. your first post in this thread). I need a little pink pill for my braincramp now....