Homemade incubator thermostat!

[rickerra]

Thanks Davaroo (and others) for linking other viable thermostat options out there. That is good information to know.
That Repti 500r sounds pretty nice for the money and has the advantage of being digital. Though you might still need a second plug on the incubator to power always-on stuff like a fan or second light.


A BIG thanks also to Rebelcowboy... for demonstrating how to get the hot water t-stat setup to temp-swing less. If I hadn't seen your video and comprehended your explanation, I'm sure I would have stuck my t-stat on the opposite side of the incubator... backside flat up against the cooler... and then been frustrated at the huge, uncontrollable temp swings. Then I would have probably called the hot water t-stat a piece of #$%@. But...

I am using one in my incubator I just build which has: 1.5" thick styrofoam cooler, 4 large paver stones w/ air gaps around them for thermal mass, 60W light/heat source, small computer circulating fan and glass pane in lid for observation.

I have the back of the t-stat about 2.5" from the light bulb (nothing in-between, direct-line-of-sight to t-stat from bulb). This has given me a sweet temperature swing.... from 99.7 - 100.2 on one gauge, 100 steady on another gauge, 100 steady on glass bulb thermo stuck in plastic easter egg filled with liquid dish soap (my homemade water weasel)... for the last 12 hours straight. I'm happy with these results.

My light bulb cycle time is 3 minutes on, 5 minutes off. (I've time elapsed recorded with a webcam for the past few days as I dial it in... geeky... I know!). So this leads me to a question.

Anyone know the cycle life of one of these t-stats? How about a normal 60W light bulb?

On/off every 8 mins = 180 cycles /day x 25 days (21 + couple days for prep) = 4500 cycles. That doesn't sound like too many to worry about... thoughts?

Cheers!

 

[Pascal PicklePants]

Quote:
Good Job!

As for the cycle life, I don't really know. The T-stat would be pretty long lived though.

I wired two 40W bulbs in-line just in case one burns out. So hopefully i won't have to worry about the cycle life of the bulbs.....unless they both blow at the same time...in which case i'll just quit

 

[nhnanna]

I would love to see your setup in pictures.

Quote:

 

[rickerra]

Quote:
Hi,
I'll post some pictures when I get home later tonight. Guess I could build my own BYC page for details too.

Cheers!

 

[silkiechicken]

Quote:
This is what I use on my home made incubator. Works so much like a charm that I get less than .1 resolution in temperature. Reason I say .1 is because my Fluke Digital multimeter temperature probe resolution is .1 and it does not vary no matter how many times I measure in each location. There is VERY little hysteresis in the unit. Hot water thermostats have huge swings. That said, because of air flow in the tiny bator, it is still not uniform top to bottom and in corners.


One note is you MUST have good airflow if you go with the preset, it is not designed to work as "preset" in still air incubators.

The incubator:

 

[Mervin]

@rickerra

I'm interested in your set up. I am currently building something very similar. One question I had is why the air gaps around the pavers. I have several porcelain tiles left over from my bathroom that I was going to use as thermal mass. I was trying to wedge them in there pretty tight, but if there's a good reason not to I'd like to know. I built mine out 1" rigid foam insulation and have a double layer plexiglass viewing window. I not quite done, so I haven't had the chance to run any trials yet though. This thread has been interesting as I've been planning on using a WH thermo b/c I have one. I would think with a significant thermal mass, the actual 6-degree swing on it would really matter too much. I'd think if you could hold 100* steady on a water weasel then that would really be what you're looking for. I can't imagine the air temp inside the box is nearly as important as the nearly constant temp in the egg.

 

[Davaroo]

Wow, ya'll take this stuff pretty personal, dont you?

I didn't say they didn't work for me - in fact, I tried them a long time ago. And they have been batted around here, on and off, for possbily longer than some of you have been here.
What I did was put them aside in the interests of getting up and running, sooner.

Actually, I would prefer newbie DIY'ers not start with anything as remotely complicated as a forced air, thermostatically controlled unit. There are some good designs out there that use none of that and produce good results in the bargain.

As another has said: Lower your stress, improve your hatches. Use the right tool for the job.
In the end the stress you relieve may be your own.

Different strokes for different folks.

 

[rickerra]

Quote:
It really would only matter when you are trying to change the temperature... like getting it up to temp... or bleeding off too high of temps. All the bricks or tiles stacked together would function more like 1 solid mass and take a little longer. But once the mass is up to the desired temp... it's all good. By spacing out my bricks, it allows air to get around them and work a little faster... but probably not noticeably faster. If I could have fit another paver in there... I probably would have! haha

I do think many of the homemade incubators I've looked at could use more thermal mass... be it rocks, bricks or sealed jars of water. This has a HUGE affect on an incubators ability to hold a temperature. As others have mentioned... you want as little airspace in your incubator as you can get away with (of course with proper ventilation... and room for the chicks... etc.). The more thermal mass you use instead of air, the more stable the temps will be. When I open the lid on my box... say while I've been fiddling around with it... the air temps will drop quickly. But as soon as I put the lid back on... all the heat held in the pavers brings the air temps back up to equalization very quickly. Similarly, an incubator with a lot of thermal mass (that's up to temp) could withstand a system malfunction like a light bulb burning out or a power failure a LOT longer than one without (given the same incubator).

The eggs themselves are small thermal masses. That is why the Egg-o-meter and those like it are slower to react to temp changes around it than the air thermometer sitting beside it.

And while sufficient thermal mass would help against temp swings from a t-stat... it's cool that we now know how to minimize the water heater t-stat cycle temperature swing.

Cheers!

 

[Pascal PicklePants]

Quote:
It really would only matter when you are trying to change the temperature... like getting it up to temp... or bleeding off too high of temps. All the bricks or tiles stacked together would function more like 1 solid mass and take a little longer. But once the mass is up to the desired temp... it's all good. By spacing out my bricks, it allows air to get around them and work a little faster... but probably not noticeably faster. If I could have fit another paver in there... I probably would have! haha

I do think many of the homemade incubators I've looked at could use more thermal mass... be it rocks, bricks or sealed jars of water. This has a HUGE affect on an incubators ability to hold a temperature. As others have mentioned... you want as little airspace in your incubator as you can get away with (of course with proper ventilation... and room for the chicks... etc.). The more thermal mass you use instead of air, the more stable the temps will be. When I open the lid on my box... say while I've been fiddling around with it... the air temps will drop quickly. But as soon as I put the lid back on... all the heat held in the pavers brings the air temps back up to equalization very quickly. Similarly, an incubator with a lot of thermal mass (that's up to temp) could withstand a system malfunction like a light bulb burning out or a power failure a LOT longer than one without (given the same incubator).

The eggs themselves are small thermal masses. That is why the Egg-o-meter and those like it are slower to react to temp changes around it than the air thermometer sitting beside it.

And while sufficient thermal mass would help against temp swings from a t-stat... it's cool that we now know how to minimize the water heater t-stat cycle temperature swing.

Cheers!

X2

the floor of my cooler-bator looks like the land of mismatched jars.

 

[rickerra]

Davaroo... to borrow from our Aussie friends.... "No worries Mate!" Appreciate your inputs!

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Thanks! I take no credit in my incubator's design. I've pioneered nothing here. Just pulled what I saw as the best ideas from many different home-built incubators.

I am pleased with how stable of temps I was able to achieve. The water heater t-stat next to light bulb trick and a lot of thermal mass (paver stones in my case) in my box have really helped.

Do both of your bulbs come on/off together from the t-stat? Or is 1 always-on and 1 cycled?

I contemplated using 2 light bulbs... 1 always-on. I like the backup feature in case of a bulb failure. But I settled on the simplicity and ease of packaging just 1.

With all the thermal mass in my box... I wonder how many degrees it would lose in a worst-case scenario (8 hours overnight). Hmm... might be worth experimenting.

Cheers!