Why does the temperature change inside the incubator?

[Joey8765]

Why does it change? It should stay the same shouldn't it?
there are no cracks or holes in the incubator so why does the temperature still fluctuate?

 

[saladin]

It shouldn't fluctuate more than 1/4 a degree if working properly and in a room with constant temp.

However, if the room temp goes up and down so will the incubator temp. The quality of the incubator will determine how much it goes up and down.

The reason there is normally a small fluctuation has to do with the heating element turning on and off.

 

[Clay Valley Farmer]

It actually gets quite complicated with a number of factors.

As posted above, with basic termostat incubator the fluctuation is caused primarily by the heat source kicking on on off. This happens because the termostat must kick off at a higher temperature than it kicks on and it takes some time from when the thermostat kicks on to increase the air temperature inside so that the thermostat sees the increase and shuts off the power to the heater.

But it is not just that simple, when the heat element or bulb is on it gets much hotter than the air and then transfers heat to the air, the air in turn must circulate and transfer heat to the thermostat, in order for air to heat the thermostat the air must get hotter than the actual thermostat. When the thermostat finnaly heats up enough to kick off there is already more heat in the air and heating element than was required to get the thermostat to the ideal temperature. This is overshoot and the temperature will continue to rise above the set point for a short while after the thermostat kicks off.

The more mass in the heating element and the higher it's actual temperature the more the overshoot. Also a small air volume, less circulation, greater thermostat mass, greater distance between heater and thermostat will all work to increase overshoot.

Things that will help give even temperatures

-Good circulation of air inside bator
-lower watt low mass heater that does not get super hot
-low mass thermostat with tight operating range
-Good insulation
-Lots of thermomass, simply adding several lb of bricks, rocks or metal can help even out fluctuations
-Steady room temperature free of drafts or direct sun exposure

There are inteligent or programable temperature controlers that can learn the heating charicteristics of the bator they can anticipate heating lag and overshoot to keep a tighter temperature range. Also there are proportional controllers that vary the power to the heater constantly rather than shutting it off and on, these can achieve much steadier temperatures.

Short artical that I think explains it well.

http://www.process-cooling.com/Articles/Feature_Article/9346bdedf75b7010VgnVCM100000f932a8c0____

 

[El michoacano]

I need help Cuz my temperature changes I have it at 37.6 an drops to 37.00 an goes back at 37.6 or 37.7 an back too 37.6 is that ok.thanks a lot..... My humidity is around 45%55% but I have it at 53%