Convotherm 4, Bottom Burner – Gas Burner technicians.

[ectofix]

olivero, what size oven is that?

[olivero]

This is a 20.20 unit.

 

http://www.convotherm.com/Product/fam_tcazeo/Convotherm-4-easyTouch-20-20-

[olivero]

Well, I am certainly happy I am not the only one with this problem……. Did it happen with one burner or both? My top one looks totally fine.

 

I can weld a stud on it from the side I am looking at it, I would prefer to do it where I drill a hole and just drop it in but it can definetley still be done.

 

I find it very interesting that these problems are coming up (referring to all the stuff I’ve had happen already), makes me think somebody missed something in their testing phase. I will have to see what Cleveland says about it as I am not too keen in spending $2-3K on replacing all of these things just “because” There has to be some reason for this other than “tough shit” especially since I was a very good boy for the last 2 years and kept my hands out of the oven and let the certified tech do all the work and now this happens.

 

I actually didn’t have THAT list with pictures, that definetley is easier to navigate, thank you.

 

I went to take a look at it again after you mentioned the heat exchanger, figured I might as well remove it now and make sure I am not missing anything.

 

 

That’s what the heat exchanger looks like the side that mounts to the inside of the unit.

[fixbear]

I have no doubt that you can weld the crack and replace the stud.  But, how do you get the flange back true so that it will hold a seal?  Flame erosion has removed a lot of metal there. All this looks like it started with flange warp-age and a small gasket leak.

 

As for the galled studs,  I wonder what alloy they are using for them.  What never seize are they using for assembly./

[ectofix]

WOW!  Those cracks are obviously far worse when looking from the inside of the oven with the exchanger removed. The rusty discoloration at 1 to 3 o’clock appears to be where flame might’ve actually leeched into the cooking compartment.

 

So, I’m guessing this is a spritzer oven?  If so, makes me think there was some warpage due to the hot heat exchanger getting quenched by cold water sprayed on it.  But…I don’t know.  I don’t have any spritzer-type ovens, and don’t want any.

 

In my situation (on my Rational), the oven’s wall didn’t have any cracks.  Just the heat exchanger.

[ectofix]

I had that same meltdown occur numerous times on our Rational 202 (same size as yours).  More about that in a second…

 

About that broken stud:  It’s spot-welded to the heat exchanger flange, so you’d need to remove the heat exchanger from inside the oven to weld on a new stud.

However, you should consider probably just replacing the heat exchanger and all ITS gaskets along with all those gas burner components you’re going to replace due to the meltdown.  I’d also replace the metal mesh burner.  So, pretty much everything for that particular heat exchanger all the way back to the gas supply feeding it.

 

NOW.  In my case, I dealt with numerous meltdowns of that ridiculously plastic burner blower/air-gas mixer…and the plastic shroud housing it all.  Initially I’d related it to an electrical connection problem not energizing the burner blower when it should and possibly causing backflash of the gas.  INDEED I DID find that the wire harness (in Rationals) supplying that blower was fragile – ultimately causing the wire strands to abrade within the plugs down to a final strand, then result in failure of the motor to operate.

 

HOWEVER…after chasing my @$$ addressing those issues and replacing several burner assemblies in a six week period, I was at wit’s end and asked my boss to call in Rational’s authorized service company.

The guy who showed up apparently had better eyes than I…had spyed a crack in the heat exchanger…and even pointed at it to show me.

I really never saw it (the crack), didn’t question it.  After all, whatever he decided to replace was good for a 30 day labor/90 day parts warranty.  If what he did lasted through those periods, then it would’ve far surpassed my bumbling through replacing melted plastic  burner components every couple of weeks.

 

SO…he replaced EVERYTHING I’ve advised you to do.  I shouldn’t say this (for fear of hexing my oven) – BUT…I haven’t had any similar problems with that oven for nearly two years.

 

As to WHY this only happened on my one-and-only 202G…I don’t know.

 

Anyway, I hope this helps.  Although I’m sure you have it, here’s a copy of their part list.  The heat exchangers are on pages 33 & 34:

 

http://download.partstown.com/is-bin/intershop.static/WFS/Reedy-PartsTown-Site/-/en_US/manuals/CLE-C4_pm.pdf

[fixbear]

Got to appreciate the power of expansion contraction with high heat over time.  How old is this oven?  Great pictures olivero.

[olivero]

Yeah, it seems pretty bad whatever happened, still trying to get word from Cleveland on it.

 

It does definetley look like the flame leeched into the interior has that carbonized look, getting everything flat and even shouldn’t be too difficult, some padding, fine grit grinding, polishing and we should be there. I won’t do a thing until Cleveland gives their OK though, not comitting that much to this oven.

 

From what I see, there are no cracks in the heat exchanger which I thought was kind of interesting, if the sprizter was to blame I would expect the cracks to be there but then again who knows. If the stainless got heavily carbonized and some of the chrome got carbonized, it could make the metal much more brittle and it would eliminate the benefit of “flexibility” in stainless which is also what causes galling. I have seen it on copper pipe before as well, it seems to be the “soft” metals that do it.

 

Oven’s barely 2 years old. It’s kind of ridiculous.

[fixbear]

f it’s only 2 years old,  I’d be looking at flame shaping, mixture, venting and  calibration.  The marks show that the gasket failure was light on set in that blow out area. And you had blue flame coming out.  Determining why it was a light set  is probably gone. A small particle near a stud or a manufacturing warpage of the flange is all it takes.

[olivero]

More High Def

 

 

The burners were calibrated about 6 months after we got the oven due to constant error codes on ignition and messed up igniters and so forth.

 

I spoke to Cleveland, after a bit of arguing they agreed to cover the parts, new heat exchanger, ignition mod, combustion blower and all new gaskets. About 3.5 K worth of parts, and then add the overnight into it.

 

Now they are going back and forth on welding it up or not, i mean there is not much choice, it’s gotta be done or the whole thing replaced. Seems pretty simple to me, I just need it from them.