Calibrating thermometers - the easy way

Discussion in 'Incubating & Hatching Eggs' started by twigg, Feb 8, 2009.

  1. twigg

    twigg Cooped up

    Mar 2, 2008
    I see a good many posts about thermometers, both cheap and expensive ones. Often folk wonder why their hatch fails, or is delayed, or they get early, bloody chicks when all seemed well during incubation.

    Cheap thermometers can be a major headache. Accuracy within a couple of degrees is fine for you swimming pool, but not for the incubator.

    So how do we calibrate a thermometer?

    Google it, and you will get a bunch of clever and complex answers, some involving iced water and boiling water with an allowance for altitude, etc.

    All good ideas that work, but there is an easy way too.

    All you need is a ball of modeling clay and a cheap medical thermometer.

    Put the modeling clay in your incubator in place of an egg. Bury your thermometer in it, or probe, or whatever you are using. When the temp stabilises, poke your medical thermometer into the clay and take it's temperature.

    The beauty of this method is that medical thermometers can be had from Walmart for about $5, and they are guaranteed accurate to 0.1F, right in the range we are interested in. Even if another method tells you that your thermometer is good at 32F, that does not mean it is good at 99F.

    If your thermometer reads the clay higher or lower than the medical one, then simply add or sutract the difference evry time you use it.

    For example, my very cheap indoor/outdoor electronic thingy, which cost $6, reads 1.3F low at 99.5F .... so it's easy. I just maked *add 1.3F* on a label on the device.

    Hope this helps

  2. conny63malies

    conny63malies Crowing

    Mar 22, 2008
    Annetta Kentucky
    i use a water wiggler or water snake from the dollar store. JUst stick the probe in and put the whole thing in the bator. or if you probe cable is long enough you can get the temp from ouside the bator without opening it. Easiest way to calibrate is to stick the thermometer (cheap plastic one like you would use for in or outside)in a cup of ice water it should 32 F . Most of the time you can slide the glass part a little bit up and down to adjust.
  3. twigg

    twigg Cooped up

    Mar 2, 2008
    Quote:For reasons I explained, this only tells you if it is accurate at 32F, assuming you managed the perfect ice/water mix, which isn't easy to do.

    Thermometers, particularly alcohol ones, do not usually behave with linear accuracy or inaccuracy. Much depends on how well the glass tube was formed.

    The method I outlined tells you exactly how good your thermometer is at the temp we want it.
  4. conny63malies

    conny63malies Crowing

    Mar 22, 2008
    Annetta Kentucky
    I got three thermometers in there anyways . After my old acurite showed me 42F inside temp one day and 115F the next.
  5. AHappychick

    AHappychick Wanna-be Farmer

    Dec 16, 2008
    oh I am going to try that, ...oh wait I just ordered a new Bator [​IMG]
    well I think I will try it anyway I never trust anything, but if my LG was pluged in right now I would already be molding an egg as I type lol.

    you know my last hatch I had 3 thermometers in my LG all a few degrees off from each other. UGG so fustrating!
    Last edited: Feb 8, 2009
  6. rebelcowboysnb

    rebelcowboysnb Confederate Money Farm

    I'm with ya on this one twigg. Calibration at 32 only proves accuracy at 32. It means jack at 100. I've been using a $3 thermometer from a dollar store for a while. Talked about it on here an cought grief saying that I couldn't prove its accuracy.
  7. twigg

    twigg Cooped up

    Mar 2, 2008
    Quote:If any one wants to use the ice/water method then I suggest they Google how to do it.

    Getting the correct mixture is not a case of simply mixing ice and water, it's tricky and needs to be done correctly or there is no point.

  8. speckledhen

    speckledhen Intentional Solitude Premium Member

    Steve, thanks for the information. I believe the single most common cause of failed hatches is an inaccurate instrument.
  9. twigg

    twigg Cooped up

    Mar 2, 2008
    Quote:Nice to see ya again [​IMG]

    Yes, that and humidity control probably cause more problems than anything else.
  10. OCchickens

    OCchickens Songster

    Jul 19, 2008
    Brea, California
    Thanks Twigg for such an ingenious method of checking temperature. I just checked mine using an old mercury thermometer I had & it was 98.2!! I've had a suspicion my temps might be low. Yikes![​IMG]

    I'm on day 18 today. Just turned the bator up a bit... Eggs seem to be developing well but maybe they're a little behind.

    Is there any hope if they've been at this temp the whole time? And with me opening to turn by hand & candling all the time on my first hatch?[​IMG]

    I so get now what they mean about using inexpensive eggs the first time. Although I'd probably be this emotionally invested even so.

BackYard Chickens is proudly sponsored by