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PostPosted: Mon Jun 22, 2009 6:00 pm 
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Junior Champion Bird
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You should be encouraging radiant heat more. This includes both the radiant heat you can see and that you can't. Radiant heat is basically just little packets of pure energy that travel until they strike something, if not reflected then this energy is absorbed by the object they strike.


So would having a heat sink like how Neil had his help (see pic below)?

Image

I'm wondering too because I currently have 1 halogen going and it's not producing enough heat and the incandescent seems to be doing a better job at it.

chookstarter


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PostPosted: Mon Jun 22, 2009 6:21 pm 
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Showy Hen
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Yes, radiant heat is the issue here. I am not quite as naive as Denis suggested, but I decided not to take his comments too badly. Of course heat is light and light is heat but it's not quite as simple as that. The issue really is: how can we all produce heat with the smallest energy input in the simplest way and get that heat transferred into the air and onto the eggs. Even though light is heat and heat is light, nobody has yet designed a hair-dryer that uses light globes to create the heat to dry the hair. But this is what we do in our incubators.
My big surprise was that halogen globes seem to create so much less heat then incandescent ones. Or produce the same heat, but require heat sinks or other gadgets to transfer the heat better. When I did the test with incandescent globes my incubator was still painted white... And yet it worked so much better. Rather than use heat sinks and/or paint the interior black I simply won't use halogens.

By the way: IM sell a lot of incubators. I have two of them and they work very well. They are white inside and they use resistance wire elements.


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PostPosted: Mon Jun 22, 2009 7:00 pm 
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I have tried halogen globes and found they didn't suit my incubator as I couldn't get enough heat out of them. The regular incandescent works best for my sized bator. The bar heater that you mentioned in the bulb thread sounds interesting Chookstarter. They are expensive at $87 a pop, but I'd love to give them a try in my incubators. I wonder if they come in different sizes. I also wonder how long they last. For that price you would hope they'd last a long time.

viewtopic.php?f=6&t=7976447&start=15

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PostPosted: Mon Jun 22, 2009 8:00 pm 
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Hi Torsten,
Lets have a look at the resistance wire idea
Quote:
Resistance wire is very cheap. Dick Smith sells is for $4 per 4m roll. The only real expense is the transformer. I am not sure if it would damage the transformer in the long run to be switched by the SSR that often. If that is a problem then the transformer would need to be on 24/7 but the heating elements would need to be switched. Let's assume two elements of 200w each, the the SSR would need to switch 400w 12V or 33 Amps which is more than the SSR I have (rated at 25 A).


Ok using Ohms law to work out the resistance required to produce 400W using 12volts R=E squared/P
R=12x12/400
Therefore you need 0.36 ohms of resistance wire, pushing 33amps thru that will melt the wire pretty quickly. This assumes that the elements are in series.
If in parallel the equation becomes R=12x12/200 = 0.72 ohms Amps are now I=E/R 16.666 amps
Or you could make 4 x 100w elements R=12x12/100 = 1.44 ohms @ I=12/1.44 8.33 amps per element
Now if I remember parallel resistors correctly you will still be pulling the full 33 amps through the whole setup. 33Amps is going to result in a very expensive transformer.
(BTW , I even have bought some of the dick smiths stuff, it is rated at I think .5 ohm per meter)
The conversions for the equations come from the table on this website http://www.the12volt.com/ohm/ohmslaw.asp

Now looking at your bator, I personaly think that the 2 compartments that the halogens are in are going to be much warmer than the egg area. Why do I think this? I think the holes you have drilled for the return air to circulate through are too restricted and as a result the fans will not push enough air thru to the egg chamber. Also the airflow is basically travelling from the fans to the return holes directly opposite and creating a dead air area in the middle section of the egg chamber.
You could try strips of tissue taped to the glass lid to get an idea of what the airflow is like, a bit like a wind tunnel with smoke.

Have you tried incandescants mounted in the heat compartments yet?

Cheers
Trev

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Last edited by TrevL on Mon Jun 22, 2009 9:51 pm, edited 1 time in total.

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PostPosted: Mon Jun 22, 2009 8:10 pm 
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Showy Hen
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Thanks for advise! It will be a few days before I get time to go to town. I'll post the results!


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PostPosted: Mon Jun 22, 2009 9:09 pm 
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A note for the readers: If you decide to try that please take great care. I know there are experts on BYP, but a lot of us aren't. Any kind of wiring is dangerous if it's not done by someone who has expertise in the field. If the supply is not calibrated precisely for the load, then the wire will either not heat up enough or it will overheat to the point of damaging things around it and can be a fire risk. When hooking it up if you have a poor join, it can create a higher resistance which can result in hot spots and is a fire risk as well. Joins need to have lots of surface area touching and they need to be very firm. The best way to join would be to solder. If your wire is bent too hard on itself then you de-rate the amount of current your cable can carry also. You want to keep your wire as straight as possible and have no sharp turns to reduce hot spots.

I guess the message is one of extreme caution. I would prefer to use an element that is pre-constructed and has a fixed determined rating.

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PostPosted: Mon Jun 22, 2009 9:52 pm 
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Chicken07, I have edited potentialy misleading info from my post.
Cheers
Trev

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PostPosted: Tue Jun 23, 2009 4:24 am 
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An SSR that switches AC is a different beast to one that switches DC current.
400W at 12V is 33amps. Good luck with finding something that can do that for less than the cost of an incubator.

I agree with what C07 is getting at but not everything she is saying. Her point though is clear, I'd just add to that warning as it is even trickier than she has outlined.
Solder isn't a good choice because it melts at about 300 degs or something.

Nichrome wire in the Dick Smith catalogue is $4 for 4m. It is rated at 1200 degs C. Thats all the info you get. So what is a safe current to run through it ? , and why isn't that specified?
To make this a more affordable option we can use the downlight transformers which are 12VAC and 50W. Using the formula P=E*E/R we get R=E*E/P or R=12*12/50 R=2.88ohms.
That gives us a minimum length of wire we can use. 2.88/13.4=215mm
A 100W transformer will handle a shorter length of 118mm and so on.
But how hot they will get is anybody's guess. How hot is 1200 degs anyway? As far as I can tell when things glow a dull red they are at about 1200 degs but don't quote me on that you'll have to look it up yourself.
Most likely to get the wire element to work you will have to force or funnel more air over the element, but you could have done that with the globe.

My tip would be forget the wire and get some 5W or 10W ceramic resistors.
A 5W resistor using 12V. again using P=E*E/R R=144/5= 28.8 ohms.
The standard size would be 27ohm which is cat no. R1636 at Dick Smiths. 34 cents.
Use as many of these (each producing 5W) as you need to make up what your transformer is capable of. 50W transformer will handle 10. It is pretty easy to make them up into a geometric grid and mount them about an inch from your fan inlet or outlet. They don't get super hot but you do twist there wires together for strength and solder for the good contact.
Here's one I made earlier, it is 25W. Pretty easy to mount these as the ceramic doesn't conduct electricity so you can make up a clip using metal if you wish.
Image

There is 10W resistors but each one costs about $1.85 from Jaycar. The value you'd want is 15ohms but it would be pot luck if your store had one.
In actual fact these resistors are wire wound resistors so actually are the same thing as nichrome wire. The difference is I know as long as I only try to run one of these resistors at 5W then they are safe, electrically and from a fire safety point of view.

I actually use these ceramic resistors in all the incubators I make these days. Well, actually I run them using 240V but I don't use the 27 ohms (or anything like it) and I put them in series. It is actually more complicated to use the 240V and you need to be more careful. The picture above I am happy enough for a 12V arrangement as long as those bare wires aren't going to touch anything and create a short but in a 240V set up they are begging for someone to brush their hand against.


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PostPosted: Sun Jun 28, 2009 7:15 pm 
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Showy Hen
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An update:

I gave up on using halogen globes. Building resistance wire heat elements is a plan for the future, but right now I wanted to get the incubator going the way it's been done sooo many times: with incandescent light globes. I tried to buy batten holders (no problem) and globes. What a surprise! Neither Mitre 10 nor Bunnings carry regular incandescent light globes any longer in Hobart. The only ones available now are coloured party globes or the candle type, all in low wattages. Incandescent globes are truly on their way out. Anyway, I managed to get four globes of 60w each. I set them up in pairs, one for each heat compartment of the incubator. It did not take long to bring the box up to temperature and I must say that the AUBER PID with SST works very, very well. It truly is a set and forget unit. And I agree with the comments about the readout not being necessary. The PID will hold the temperature and an alarm is really all that's needed.
Next step: check my various thermometers

Image

These are the results. When I set the AUBER controller to 103 (!) my Brinsea Spot Check reads 100.9, both alcohol thermometers read 100.5.
This would be on the high side but I learned to run my two IM incubators at 101.5 for best results. Only trials will tell which temperature gives the best results in this unit. But it is interesting to see that the AUBER probe registers about two degrees F higher than my thermometers.

First temperature checks at various spots of the box indicate equal temperature throughout, but I am still checking!


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PostPosted: Sun Jun 28, 2009 10:48 pm 
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Champion Bird
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Great to see some positive results mate.

BTW try and source more globes, some globes run for ages in the incubator, and some blow in days.

Regards
Trev

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PostPosted: Thu Sep 24, 2009 11:22 am 
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Showy Hen
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My incubator has been running for the last two months and I hatched lots of chicks. It works so well that I built a second one to use as dedicated hatcher. I have written a detailed report about my experiences. It includes plans etc. You can look at it on my website:

http://www.growyourownfood.com.au/poultry/chickensix.htm


Cheers
Torsten


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PostPosted: Thu Sep 24, 2009 11:32 am 
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You've done a great job of that web page Torsten. I'll link to it in the stickies.

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PostPosted: Sun Jun 13, 2010 6:36 pm 
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Junior Champion Bird
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torsten wrote:
An update:

I gave up on using halogen globes. Building resistance wire heat elements is a plan for the future, but right now I wanted to get the incubator going the way it's been done sooo many times: with incandescent light globes. I tried to buy batten holders (no problem) and globes. What a surprise! Neither Mitre 10 nor Bunnings carry regular incandescent light globes any longer in Hobart. The only ones available now are coloured party globes or the candle type, all in low wattages. Incandescent globes are truly on their way out...
Hi torsten,
are you still getting by with "incandescent light globes" or have you converted to a different heat source?.


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