Effect on bator RH due to ambient intake air

you forgot to take a few variables into your calculation. The weight loss of the eggs is due to moisture loss which in turn results in higher humidity. Also air speed changes the results as faster air flow helps to turn moisture into humidity so the eggs are loosing moisture at a faster rate.

most of us don't care about humidity as its a rough guide to get us to the first weighing/canderling personally 28 would not be a starting point I would be happy with as I prefer 35 for a relative dry hatch especially in a forced air incubator so I would have added a small container of water.

From a purely scientific approach you would have to run the numbers with no eggs in the incubator and the incubator sealed in a plastic bag

hodor said:

Your bator RH is too low, adding water will fix this. Experimenting adding water to containers with different surface areas until you hit the level you want (40% per your statement) is all you need to do. This is the using observation as a guide Miran was speaking about. Since you have posted this "question" on a Chicken forum in an area about incubating their response is very reasonable, it may not answer your specific question but would solve problems relating to incubating - the very purpose of this forum page.

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Please let me try again.
My bator RH, as described in my initial post, is without any water, eggs, or anything other than the bare metal trays. That trial was an attempt to see the lowest possible RH the bator would provide. However, the bator comes with a single water tray and a cover for that tray (it covers some ~80% of the water surface), and a wick to put in that tray. So, if I put the tray in with the cover and no wick, I get an RH of 53% in the bator, no lower. That RH is too high, not too low.

hodor said:

Yes it is "maths" and "science". Miran raised some very valid points here about there been lots of variables, which will increase further in number when adding eggs which all their variables in size, surface area, shell thickness, mass and permeability among others.

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I apologize if my initial question was not as obvious as I thought it was. Take a given intake air RH and temperature, and only change the temperature, you should get to a reasonably known RH value. I didn't...and I was asking if anyone could say why. To say there are a lot of variables isn't answering why, its merely waving hands and saying; "you can't determine this", imo.
Well, its a given that if you have too high an RH in the room the bator is in, there will be no way to get a reasonable RH in the bator. And while RH isn't the goal, being able to achieve a reasonable egg weight loss requires being able to control the RH sufficiently. If the RH is too high, eggs will not lose sufficient moisture...period. Perhaps most people are struggling to provide sufficiently high RH to achieve proper weight loss...which you can solve by adding water...but my problem is that I am worried I will not be able to achieve sufficient low RH, and provide an environment for the eggs to loss an adequate amount of moisture. Hence my tests before placing eggs.

hodor said:

Anyway the incorrect statement above gives insight into why your calculations fall over. So to answer your "question" (if I have identified it correctly), there is something changing between the room and the bator due to the differences in RH which create an effective concentration gradient. I.E the RH outside the incubator is high and inside low and the water molecules move from an area of high concentration to low concentration. I hope that helps.

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I'm sorry, but no, that explanation means nothing to me. Could you elaborate on that thought?

hodor said:

In the future maybe you should address your own short comings before been so critical of others, or better yet just more understanding, especially of people that take time out of their days to help you.

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I posed the question to address my shortcomings, my ability to comprehend everyone else's feelings in text may not be good, but it has nothing to do with a C$1300 bator defying the laws of physics.

I'll try to explain again.

It seems you understand that RH decreases as temp increases due to airs ability to hold more water at higher temps, great.

The temp is higher in the incubator so the RH is lower.

The incubator is not sealed air tight, air moves in and out freely.

Now you can think of air as a solution of different things with water diluted into it.

This solution has a natural "want" to have the same RH everywhere. As RH is relatively low inside that means that water will naturally move into the air in the incubator. Raising the RH and dew point.

Another way to test the same principle is to have two buckets of water connected by a small pipe which starts sealed as you fill both buckets with water. One with fresh which is heated and one with cold salt water and then carefully open the pipe. You could have both buckets stirred individually to speed things up.

In this case salt will move into the lower concentration of the freshwater, it will take a long time, but eventually it would balance out. Eventually there would even be more salt in the hot bucket as hot water can hold more salt than cold (not very much more of normal salt, but some)

Anyway you can think of water as air and salt as humidity in this example.

If it's not clear let me know and I'll make a better post when I'm not on my phone. I haven't done much chemistry for years so coming up with good examples is a stretch

hodor said:

Another way to test the same principle is to have two buckets of water connected by a small pipe which starts sealed as you fill both buckets with water. One with fresh which is heated and one with cold salt water and then carefully open the pipe. You could have both buckets stirred individually to speed things up.

In this case salt will move into the lower concentration of the freshwater, it will take a long time, but eventually it would balance out. Eventually there would even be more salt in the hot bucket as hot water can hold more salt than cold (not very much more of normal salt, but some)

Anyway you can think of water as air and salt as humidity in this example.

If it's not clear let me know and I'll make a better post when I'm not on my phone. I haven't done much chemistry for years so coming up with good examples is a stretch

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I am in central Ontario, nowhere near salt water, not sure if that matters, but its a fact. Again, I feel really dense for not getting your point, please bear with me. Could you explain it more?

FWIW, the bator is sealed, albeit not in a plastic bag, but sealed except for a vent and a tub of fresh water (which was not present during my initial tests).

Maybe my explication is confusing. Especially the last one. When I'm home on the computer in a few days I'll write up something properly.

hodor said:

Maybe my explication is confusing. Especially the last one. When I'm home on the computer in a few days I'll write up something properly.

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Upon first reading I didn't get it, but after sleeping on it and re-reading it, it makes sense now. It answered my question, although I would argue that the Ova Easy 100 is far more sealed than most bators. But the idea that the dewpoint could be different is what I didn't get, and you've explained that, so thank you very much.

As I have said to Brinsea's founder, the Ova Easy 100 cannot be used as an egg incubator with what comes with the basic bator. The water tray and cover supplied will not provide an adequately low RH, and eventually I had to tape it shut and poke a very small hole in it to get down to 40% in the bator (not a magic number, but a reasonable starting point.) Of course this didn't offer an easy way to provide the boost required on lockdown...so not a viable method. The other option, throw out the tray and just put a small bowl (or, as I found, it would have to be a bottle with a very small neck) meant you'd be in there at least every day adding fresh water...also not a viable method.

Now the humidity pump with a piece of wick does work...its just the darn pump is loud!

Anyway, thanks very much for saying it in a way that allowed me to get it.

No problems.

Good luck with your incubations.

interesting post as I like science.
Im wondering if someone has told you that opening a incubator is bad. Theres no problem with removing the eggs reconfiguring the incubator then placing the eggs back inside as long as you are not doing it late in the hatch. The most important time to turn the eggs is early during the incubation so setting then up for hatching a day or two early is not going to cause a problem. I have no fear of removing the eggs and replacing parts as long as the room is over 70 and im going to be less than 30 minutes its not going to make any difference. (florida we never get lower than 70 but there's science reports that take the eggs down to 35F for a hour with no adverse affect on hatch rate).
During lock down when the humidity is set higher then you really don't want to open the incubator is case a egg has piped. The small pip hole will allow humidity inside the egg to escape quickly which can result in the membrane drying out (shrink wrapping). As you have a humidity pump your incubator may be able to recover humidity quickly which allows you more lee way that a cheap made in china incubator that can take 30 minutes or more to recover humidity.

gpop1 said:

interesting post as I like science.
Im wondering if someone has told you that opening a incubator is bad. Theres no problem with removing the eggs reconfiguring the incubator then placing the eggs back inside as long as you are not doing it late in the hatch. The most important time to turn the eggs is early during the incubation so setting then up for hatching a day or two early is not going to cause a problem. I have no fear of removing the eggs and replacing parts as long as the room is over 70 and im going to be less than 30 minutes its not going to make any difference. (florida we never get lower than 70 but there's science reports that take the eggs down to 35F for a hour with no adverse affect on hatch rate).
During lock down when the humidity is set higher then you really don't want to open the incubator is case a egg has piped. The small pip hole will allow humidity inside the egg to escape quickly which can result in the membrane drying out (shrink wrapping). As you have a humidity pump your incubator may be able to recover humidity quickly which allows you more lee way that a cheap made in china incubator that can take 30 minutes or more to recover humidity.

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I've done some tests to see how long the recovery is, how much humidity is lost, etc...I think saying it doesn't matter is, well, inaccurate. For some reason, I think, we are back to people saying how eggs should be hatched...not the point of this thread. Please don't take offence.

BTW, Brinsea Founder is in Florida, and he told me they can't try anything there??