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  • I have two imperial gas convection ovens. One will drop 25 degrees before recovering. The second drops 50 degrees before recoving. What would cause this to happen.

    guest created 3 months, 4 weeks ago 1 Member · 15 Posts
  • guest

    Member
    June 24, 2019 at 12:00 am

    I have two imperial gas convection ovens. One will drop 25 degrees before recovering. The second drops 50 degrees before recovering. What would cause this to happen.

  • fixbear

    Member
    June 24, 2019 at 3:28 pm

    Temp controller, sensing probe location, and  delayed ignition comes to mind.  A model number would help if you want more info.

  • olivero

    Member
    June 24, 2019 at 4:40 pm

    I would guess more in the thermostat section of things, most gas controls won’t allow continuous attempts of ignition and loosing 20*F would take more than a minute or 2 which is about how long it takes for a gas lockout to occur.

     

    Could be thermostat needs calibration or the probe is so covered in carbon it’s essentially insulated.

  • fixbear

    Member
    June 24, 2019 at 6:13 pm

    Without the model number it’s impossible to tell.  Some had a modulating temp control.

  • ectofix

    Member
    June 24, 2019 at 7:05 pm

    fixbear wrote:

     

    Some had a modulating temp control.

    Never seen one on a convection oven.  Even ones in a range unit.

     

    Yep.  A model number would be nice.  From the problem described, sounds like it’s a snap-action KX tstat.  A mechanical control which DOES require calibration…and then a dab of fingernail polish. 

    To lock the calibration screw in place once it’s adjusted.

     

    The one that’s 25° off isn’t unusual.  I’d simply get it calibrated.  The one that’s off by 50° is a bit much and might need to be replaced.

  • olivero

    Member
    June 24, 2019 at 7:49 pm

    I agree with that.

     

    Normally when they swing way off, it’ll never work right again.

  • sshepos

    Member
    June 25, 2019 at 7:09 am

    ICV-1

  • sshepos

    Member
    June 25, 2019 at 7:09 am

    ICV-1

  • fixbear

    Member
    June 25, 2019 at 8:08 am

    ectofix wrote:

     

    Never seen one on a convection oven.  Even ones in a range unit.

     

    In the early eighties to mid nineties Soutbend and masterchef both used them in convections.  They would hold about 2 degrees when right. 

     

    This one is as you mentioned, snap thermostat.  But also has a dual ignition Fenwal with a 3 try proofing and dual burners.. It all comes down to monitoring the temp control for when it closes and opens and watching the burners for ignition. 

  • olivero

    Member
    June 25, 2019 at 9:33 am

    Regardless of the style, I really think it’s a thermostat calibration issue, either it’s out of whack and can’t be saved or it’s just calibration. 

     

    I really doubt it’s delayed ignition. Unless it lights, loses the flame, misses, misses, lights, then loses the flame again. which would be odd, not unheard of, but odd. Which causes it to heat up slowly. BUT if it’s hitting the setpoint when it’s first turned on, I would think it’s thermostat related, if it’s really slow going, then perhaps it’s burner problems.

  • sshepos

    Member
    June 25, 2019 at 9:44 am

    thanks for the answers, I’ll start with them.

  • fixbear

    Member
    June 25, 2019 at 11:13 am

    I fully agree to it likely being T-stat problem,  bu as techs we shouldn’t rule out all possibilities.  I have seen the cap tube on the stat crimped and restricted so that there is a delay.  But more often I have seen the sensing bulb miss mounted and touching the oven wall delaying the true temp.  Parts are expensive today.  So I would use my DVOM and temp meters to actually determine what is happening.  The 2 burners are independent to light.  But will cross light after a period of time within the 3 tries. A delay of 30 seconds or so. If it’s a high liquid load in the oven it will drop considerably in that time.

     

    I’m a bit old school,  and like to know what is really happening and not guess. Unfortunately thay’s hard not being in frount of the machine and seeing, hearing, and monitoring it as it happens.  That’s why intermittent s are so hard.

  • olivero

    Member
    June 25, 2019 at 2:57 pm

    I whole heartily agree with verifying what is bad, no doubt with that.

     

    I was just pointing to the thermostat as a starting point to troubleshoot, but troubleshoot one must in order to verify it’s the correct thing, I didn’t mean that was it and just change it, just pointing where to look.

     

    I think we do pretty good over the interweb, lol. 

  • sshepos

    Member
    June 26, 2019 at 5:47 am

    I agree and will start there. I don’t like just changing parts

  • olivero

    Member
    June 26, 2019 at 1:42 pm

    Cool, you know how to test a thermostat?

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