different temp readings which one is right?

[eggybread]

hi all, i was hoping for some advice. I currently have some eggs in the incubator , Im, using a small covatto still air incubator. the last batch of eggs I tried to hatch failed and I figured the temperature was too low. the thermometer on the covatto i have just has a red line showing where your temp should be at this is supposed to be 100 f. however the last batch of eggs I left go till 25 days. when i broke open the unhatched eggs some had dead chicks inside and they still had some yolk sack left to absorb so i figured the temp was too low.
this time i have three different thermometers in the incubator the one attached to the covatto (mercury)reads on the red line, annother thermometer(alcohol) is reading about 98 f and annother thermometer(digital) is reading 104. dont these seem to vary a lot and which one should I trust??? has any body any experience in using the covatto incubators?

 

[lockedhearts]

Never heard of the bator brand but go to Wal Mart and get a Digital Thermometer/Hygrometer and use that, you can calibrate those easily too.

 

[TerriLaChicks]

No experience w/that brand, sorry but you definitely have too wide a variance in those temps! I agree, go to Walmart & get the Accurite thermometer/hygrometer, you can do a search here for directions on how to calibrate it, & get a water wiggler to insert the probe into to simulate the interior of your eggs; if you can't find a water wiggler you can put water in a ziploc back & double it over & tape it (you can do a search for both of these items too, for more info).

 

[Akane]

A still air will have a variety of temps. Mine will vary up to 6f from the center on the eggs to down low on the sides and my hatches are always on time. You want to take the temp from the thermometer on the eggs. Like this:

The black rectangle off to the side is a digital thermometer/hygrometer. It is accurate and tests the exact same temp as the one in the middle when both placed in the same spot in a room. However it consistently reads around 96-97F while the one in the middle reads 100-102F. That's the difference you'll find in different areas of a still air. That's why you measure on the eggs. If you fill the incubator up a lot it's good to rotate the rows of eggs so that the same ones are not always on the edge. Otherwise some will hatch at different times than the others because they incubated at different temps. That's the problem with still airs.

(I know I set a dirty egg I probably should not have in my first time hatching)

 

[eggybread]

thanks for the replys, the digital thermometer i have is one of the hygrometer thermometer types.
and i have a similar one to the one in the photograph but i had it on the floor of the inubator, i will place it on top of the eggs and see if it changes.
thanks again ...i'll kick myself if annother batch of eggs fail!