Originally Posted by geosheets
I got one... you can see my bator on my BYC page. The thermostat has a 2 degree differential and seems to be fairly accurate yet I've been having some trouble keeping my incubator at a steady enough (to make me happy) temp. Of course the bator is full of eggs so I'm not going to modify it right now but I will need to play around with moving the sensor to see if I can get less than a 2 degree fluctuation. If not, I may wire in another stat and use the one on this controller as a high limit cutoff. The humidistat is very accurate and has worked flawlessly with a fogger attached to it. I just hatched my first batch out of it a few days ago
I checked out your BYC page. Good looking incubator. I also looked at your choice of heating elements. I think this might explain your 2 degree on/off of your thermostat. The PTC heating elements get very hot and take a long time to cool down. I suspect instead of a 2 degree temp variance with your thermostat, you are actually getting a overshoot of your desired temp setting. Basicly, even when your thermostat turns off the power to your heating element, it is still provideing a good deal of heat. To compound this problem, you have your heating element wraped in what looks like copper wire to hold it in place. I know you said you planned on changeing this and hopefully you did, but incase you havent. The heating elements work by provideing resistance to the electrical current flowing thru the heating element. The resistance causes the element to give off heat. When ever you increase the size of the element, you also increase the resistance. As resistance is increased, temperature will decrease. If you decrease the size of the heating element, the resistance is decreased causeing the element to get hotter. In the case of your setup that you have posted on your BYC page, you show the heating element wrapped in wire. The wire does not have the same resistance to electrical flow as the heating element. Contact between the wire and the heating element, at more than one contact point, will decrease the resistance and will cause the element to put out more heat than it was designed for. It could cause the element to overheat and burnout or maybe even cause a fire hazard. It will also cause the element to consume more electrical power.
While looking at the PTC heating element I also noticed that it had three wires running to it and that it is rated for 500W. By removeing the middel wire from the heating element, and just connecting to the two outside connecting posts on this element, you can reduce your wattage to about 250 watts. You would run the two wires from your thermostat directly to the two outside connection post on the heating element. This should provide more than enought heat to keep your incubator at the correct temps, reduce your power consumption, and reduce the differencial between your 2* on and off fluctuation of your thermostat.
If you have a electrical test meter, you can check the OHM reading between the two outside post of you heating element to get a measure of resistance. This ohm reading should be in the neighborhood of about 60ohm's. A lower reading than 60 will mean more heat, and a reading of more than 60 will mean less heat. I currently am running 80 ohm's using nichrome wire and find this might be a little cool in my large cabinet incubator. I have also used 60ohms ( pretty much standard in the Dickey and Sportman incubators) and find that to be a tad to hot, so i am considering trying 70ohms in my next incubator.