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Calibrating/Testing Condar Probe Flue Thermometer???

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by BurnIt13, Dec 14, 2011.

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  1. BurnIt13

    BurnIt13 Minister of Fire

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    So I pulled an oooopsie when I cleaned the chimney a few weeks ago. I was so eager to try my new sooteater I forgot to take my Condar Flue thermomter out of the stove pipe. OOOOPS. Made quite the racket when the sooteater spinning at 2000 RPM went by it.

    Anyways, as soon as it happened I pulled it out. The probe rod had a slight bend to it but no obvious damage. Now surprise surprise, the temp reading is a bit off. When the stove is ice cold the thermometer reads a little lower than it used to. Here is a pic from Condar's site.....when it is at room temp my thermometers needle is at the "F" in FlueGard.

    [​IMG]

    Is there any way to adequately test this thing? Putting it in the oven was my first thought but that wont work because the coil is designed to be outside the pipe, so it would read way high. How about sticking the probe rod in a pot of boiling water? It would only verify the low end of the scale though.

    Any thoughts? It appears that I can loosen the screw and manually turn the face to correct for off temps.

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  2. Highbeam

    Highbeam Minister of Fire

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    The rod has nothing inside. Bending it did not cause any issues. All meter reading movement is caused by the bimettalic coil spring right behind the face.

    There is no easy way to calibrate a probe meter. Further, the condars are famous for non-linear measurements so if you correct it to read right at 200 degrees then it will be way wrong at 1000.

    Don't feel bad, I ran the brush right past my probe meter this summer when I swept my chimney. I didn't bend it but I felt stupid. I'm actually more worried about deforming or enlarging the holes in the double wall pipe causing the meter face to sit crooked and be leaky.
  3. Creature

    Creature Member

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  4. BurnIt13

    BurnIt13 Minister of Fire

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    Well I just read through some pretty exhaustive testing/analysis you guys performed with this thermometer.
    http://www.hearth.com/econtent/index.php/forums/viewthread/51149/

    And the follow up thread with input from Condar.
    http://www.hearth.com/econtent/index.php/forums/viewthread/51880/

    And it seems the conclusion was that the thermometer runs a about 20% high on single wall pipe and seams to be calibrated to double wall.

    Another conclusion out of those threads is that it CANT be calibrated. Sure you can loosen the screw and turn the face but all your doing is adding an offset nothing more. It also cant easily be tested outside of the flue. The coil is calibrated to have the magnet and rivet thingy between it and the double wall pipe.

    That said, my concern is that after I ran the sooteater past the probe, the probe now reads low at room temp. This makes me wonder if I screwed up its "thermo-mechanical properties". I would hate to have it read low across the board. I'm mostly worried about having 1200 degree temps when it reads 800. I'm not sure I trust it now after I beat it up a bit.

    Here is a quick pic of the thermometer at room temp (68 degrees). What do you think??? I know my other two Condar stove top thermometers appear to be fairly close to room temp. Is it unreliable now?
    [​IMG]
  5. Todd

    Todd Minister of Fire

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    It might be reading that low because you have a cold stove and cold air dumping down the chimney, could be right on. Pull it out into the room and see if it goes up some.
  6. Highbeam

    Highbeam Minister of Fire

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    The probe is just a solid shaft of metal meant to conduct heat to the spring behind the dial. Previous research on this site has shown that the condars come pointing at room temp (good for marketing) and then as temps climb, they read high. Up to 20% error at an indicated 1200 degrees. If I were you and could not see any physical damage to the thermometer other than the probe rod then I would loosen the nut and point the arrow to the proper room temp. Run the stove and verify the expected operation. If the needle moves in a jumpy fashion or just plain doesn't move then replace it.

    You need to trust your equipment. That sooteater must really beat the heck out of the pipe to have spun the dial.
  7. cmonSTART

    cmonSTART Minister of Fire

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    I love this site. Threads like this crack me up! I love that you guys are analyzing your probe thermometers for error.
  8. pen

    pen There are some who call me...mod. Staff Member

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    Even if it is off, it should still read consistently.

    Use other indicators of burn such as what it looks like, burn time, stove top temps, and use that for a while to determine how the fire is burning and just observe what that probe is reading under normal conditions. If you find it reads low, then just adjust what you know is your max temp accordingly. Or, as you mentioned, just undo the set screw and turn the face till you put the "redline" where you want it.

    Or, you could always buy another one and swap them back and forth to compare.

    EDIT: Had BG not swapped probes with me and I wound up being interested in finding the older 3-19 probe which reads a little better I believe (and does not have the different temp ranges) I was just going to paint the other probes face plate and let the fire rip one day and see where that thermometer was reading and mark my own "redline" on the face. Then do a low burn and mark the face accordingly there. The wife (and I for that matter) really don't give a flying poo what the actual temps are, just what is hotter or cooler than "normal."

    pen
  9. Highbeam

    Highbeam Minister of Fire

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    Yes but what is "normal"? We so often get people underfiring or overfiring without knowing it. The flue is rated to a specific temperature and that is why I want to know that real tmperature of my stove's exhaust. You eveolve as a woodburner when you have equipment and knowledge that together allow you to operate the stove properly.

    This is nothing cmon. That other thread has men adding digital thermocouples to their flues with all sorts of wires hanging out trying to figure out how just what a steaming piece of crap that the condar probe meter is. There are no alternatives to that condar meter so we have to make it work as best we can.
  10. Wyld Bill

    Wyld Bill New Member

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  11. Treacherous

    Treacherous Minister of Fire

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    Maybe not as aesthetically pleasing but you are approaching thermocouple & digital LED pricing here.


  12. WES999

    WES999 Minister of Fire

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    That looks like a nice quality thermometer, but I think the max temp is just too low. It is quite easy to get the flue over 1000 °F . You really need one that goes up to 1500 °F .

    As Treacherous said, for that amount of money you could get a digital controller, use a long TC wire and have the box upstairs where you can easily see what the temp stove is at.
  13. pen

    pen There are some who call me...mod. Staff Member

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    They are rated for a specific temp but I haven't seen one yet damaged and consistent over firing was to blame. Not saying it hasn't happened, I just haven't seen it.

    My thought considering the possibility of a failure and the devastating things that could result; is if the manufacturers were really worried about that they would have a recommended (or their own) way of measuring the temps.

    "normal" to me is found w/ a wood stove much like finding how how to drive a car in snow / ice. Comes from experience. You just need to hope that the common sense you have is enough to get you through safely as you gain experience.

    I'd be interested to know what percentage of wood burners using double wall or class A pipe actually measure the temps (flue or otherwise) of their operation.

    It would also be interesting to be able to lower a probe down a flue that is in operation to see how much the temps drop as it climbs the stack.

    pen
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