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  • Convotherm 4 Wall crack, Top burner

     olivero updated 2 years, 2 months ago 1 Member · 10 Posts
  • guest

    March 13, 2018 at 12:00 am

    Hello everyone

    Not sure if you remember a while back I had another post regarding a similar problem where the wall of the oven had multiple cracks in it, supposedly from the burner gaskets leaking and I guess it somewhat carbonized the stainless and made it brittle, that was the bottom burner which was repaired, welded the cracks up and all that fun stuff.

    Here is the older post.

    Convotherm 4, Bottom Burner – Gas Burner technicians.

    Now I am seeing a similar thing on the top burner, this I noticed after having to change the igniter on the burner, since its not extending past the gasket area Cleveland is not worried about it being a problem right now but as all cracks go, they tend to keep cracking so I am sure I will have to deal with it again.

    I replaced the gasket when I changed the igniter but I can’t wrap my head around how this crack developed in the exact same spot as one of the cracks on the bottom burner.


  • ectofix - Nashville

    March 13, 2018 at 4:38 pm


    You’re sure giving me fair warning on what I should expect to occur on any of my seven gas Rationals.  Rational’s design and Cleveland’s (I mean Convotherm’s) are way too similar.

    However, your Convotherm 4 unit can’t be more than three years old…while my Rationals are 2010ish models.  So, I hope your problem is, indeed, unique to Convotherm.

  • fixbear - ADK NY

    March 13, 2018 at 6:19 pm

    doesn’t Rational use a post burn air flow?

  • olivero - Florida

    March 13, 2018 at 7:29 pm



    One thing I’ve learned so far is that Cleveland’s combi ovens have been no pretty sight in their early days. the OGS 20.20 had some pretty narly (excuse my lingo) software problems until they got caught and corrected.


    The Convotherm 4 I believe is no exception and since it is fairly new I think we are still ironing out some problems, they have come out with multiple versions of different parts already which just proves the point.


    I am just genuinely concerned because of these problems, a restaurant gets a cracked wall like this, they’ll have to pay high dollar to get it fixed OR buy a new oven.


    No small “woopsie” to me. I am just wondering if its only ME or if anyone else has had it.

  • ectofix - Nashville

    March 13, 2018 at 8:08 pm

    No.  Rationals use a metal mesh burner much like what’s pictured:


    That burner is inside a tubular heat exchanger for hot air…or a series of non-removable heat exchanger plates within the steam generator (permanently welded into the tank).

    In both cases, the burner system is comprised of a non-regulating gas valve FIRST (it just meters gas flow, much like the idle mixture in a carburetor, so long as pressure is adequate and constant), an air-fuel mixing chamber…and then the burner blower.  The latter two (mixing chamber & blower wheel) are made of plastic.  The last stage is the actual metal mesh burner.

    A manometer is only used to test incoming gas pressure.  Setting proper gas flow to the burner requires a combustion analyzer to measure CO & CO2.

  • olivero - Florida

    March 13, 2018 at 8:14 pm

    Ever tried firing one of those burners in your hands? I did it once…. Didn’t look nearly as cool as that picture.


    I wonder if Rationale and Clevelands factory are at the same address, what you described above is exactly the same as Cleveland.


    It’s an interesting setup and I get it, spent hours and hours on tech support regarding that “zero gas pressure system” as they call it.


    The thing is ;gaskets can leak, but for both to have a crack on the exact same side, exact same stud. To me that smells fishy, like manufacturer flaw fishy, right side of the hole is completely 100% clean, not a single flaw or imperfection in sight, but the left side for some reason is just failing.


    It’s odd. 

  • ectofix - Nashville

    March 13, 2018 at 8:32 pm

    Both manufacturers are in Germany, but no – not the same address.  I looked into that years ago. 

    I think they use many parts from the same vendors, though.  Burners. Blowers.  Motors.  Elements.  Valves.  Electronic boards and such.  All German.


    I’ve wanted to fire one up in the shop.  I’ve done boiler (torpedo) burners:

    Burner Bench Test (natural gas) – YouTube 


    …and target (fryer) burners:

    Target Burner – YouTube 


    Just haven’t set my mind to putting everything together for a metal-mesh burner. 

    Also wanting to do an IR burner (Frymasters).  Haven’t done that yet either.

  • olivero - Florida

    March 13, 2018 at 8:43 pm

    Cool, they are pretty neat. I just kind of pulled mine out and fired it to see what was wrong with it.


    I was young back then….. well, 4 years ago when I had to troubleshoot it for the first time.


    I am kind of hoping I am not the only one to experience this problem.

  • ectofix - Nashville

    March 13, 2018 at 9:00 pm

    Reminds me of a Cleveland kettle call I ran years ago at a Buca di Beppo Italian restaurant.  A KGL-40 I think.  A somewhat similar burner design:


    Well HEL…uh – I mean HECK!  I thought Frymaster fryers could go BOOM when things weren’t right!


    The kettle’s burner wasn’t EVEN accessible to do any sort of visual inspection, so I just HAD to run it to see what the complaint was. Ya know?

    OMG!  THAT KETTLE resounded with the LOUDEST BOOM I’ve ever heard!  Made the walls rattle!

    From there, I had to unpin the kettle from the floor (lead bang pins anchored it down) to access the gas components.  I removed the burner assembly and that metal mantle (for lack of a better term).  The round cylinder part of it had broken loose at the welds.

    I think THAT happened first.  The BOOM was just the consequence of that.

  • olivero - Florida

    March 13, 2018 at 9:07 pm

    I believe it, that sounds like quite something. I know exactly what you mean, the reason I even found this was because when the burner fired, it sounded like a gun went off in the kitchen.


    Had an error code for burner misfiring or not firing and I go, well… hmm lets have a look (Cleveland has a MA measurement in their service mode) hit the button to fire that burner, waiting…








    Did the most amazing single finger death punch to the off switch on the unit. Had the cover off the side so everyone’s coming over like “what was that?” One of the chefs go “AAAAH! That’s what I was hearing earlier!”


    Cheeeesh, scares the cahoots (for lack of a better real word) out of me sometimes with this stuff.

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