Combi Oven Uneven Cooking

[ectofix]

Not a Rational.  Just one cabinet probe at about 10 to 11 o’clock from the upper elements (or heat exchanger).

 

Read my edit above about the quench valve.

[olivero]

True, no doubt about it. But I haven’t seen many convection ovens about 6 feet tall by some feet wide. 

 

Would make sense to have 3, 1 in the bottom, 1 in the middle and the last one in the top, or at least 2 average them and your done. As far as i know, Rationale and Alto Shaam have more than one sensor in their cavity right?

 

On the quench valve, I haven’t noticed any more water coming out the drain, I could watch a bit closer but I haven’t seen any.

[olivero]

On the quench valve, I haven’t noticed any more water coming out the drain, I could watch a bit closer but I haven’t seen any.

 

It’s not a new problem, apparently been like this for a while, if the chef puts the core probe at the very bottom of the oven, it doesn’t undercook anything, it overcooks part of the top.

[bush]

ohm both of the HSI for burners, i suspect lower burner ignitor is failing.  For preheat from cold oven, all may work well.  When oven is preheated and product loaded, there will be a call for heat, the upper burner may work fine, the lower may not light off on the first or second trial for ignition and much time passes.  By then the chamber has reached temp and the call for heat is no more.  does this sound likely?

[olivero]

I guess it’s possible. But even then, the circulation of the air in the oven would pretty much nullify that effect, supposedly at least, the bottom burner does not always ignite intentionally, seems like its based on demand. Kind of like multistage cooling systems, depending on load more compressors come on.

 

It also attempts a relight pretty much instantly if it fails, maybe a 1-2 second lag between them but I do get where you are coming from.

 

I ohmed out both igniters about 3 weeks ago or so, both were well within their range (I can’t remember the number) but at the time I was happy with them.

[bush]

Keep in mind, there is only one temp sensor.  There will never be a call for heat for just the top or for just the bottom heat exchanger.  As for the two blowers circulating heat equally from one working heat exchanger,  it simply can’t.

 

 

 

Sent from my Verizon, Samsung Galaxy smartphone

[olivero]

True, I do seem to recall having watched the call for heat go through and it would only light the top burner, I never fully confirmed my theory but if the bottom burner doesn’t light for 2-3 minutes whereas the  top burner is lit, it would either error out or finally light the bottom but I doubt those couple of minutes would make a major difference in a cooking cycle.

 

I would not expect the top heat exchanger to carry the load of both but in terms of the air circulating around and evenly heating, I doubt those minutes matter.

 

If it were a radiating heat type system like a residential electric oven with heating elements and no fan, I could see if the lower element was dying out and the top was doing good, you would have a significant difference but with the turbulence and air movement, I am having a hard time understanding how the temperature could be so different unless the air circulation for some reason just wasn’t circulating properly or if the lower fan was running too slow or too fast in comparison to the top one.

 

I believe they have speed measuring modules or functions so the unit can see how fast the fan is turning and adjust as much depending on how the oven is programmed.

 

I do find it interesting that if the chef puts the core probe in the lowest pan,  it doesn’t go uncooked, its not like the unit can’t facilitate the heat needed, it just seems the distribution or evenlyness is the problem.

[fixbear]

I’m referring to a smoke test unit to be able to see the air flow. 

[olivero]

Ah, never heard of that before. How does that work?

[fixbear]

I guess it’s possible. But even then, the circulation of the air in the oven would pretty much nullify that effect,

I would not expect the top heat exchanger to carry the load of both but in terms of the air circulating around and evenly heating, I doubt those minutes matter.

L contrair.  Each area will primarily circulate in it’s own zone with maybe 10 to 15 percent mixing  Are the ignition modules identical?  With that much delay, it will definitely affect cooking from top to bottom.  If the manufactorer did built in a delay, they would have delayed the top burner, not the bottom.  Heat rises.

 

Hot surface or spark ignition?