Convotherm 4, E05.1.8

[olivero]

Yeah, definetley good to keep around. I save such things as well for times like this.

 

I haven’t checked but I figured you would ask. I am going to get the combustion analyzer from the building its in later today and then check it. I am going to go pull the burner now and see what I find.

 

Its pretty much impossible for something to fall into the flue of the heat exchanger, the exhaust on the oven is sitting under a hood, somebody would have to do a 3 point shot with a ball of foil to get it in there.

 

Hood cleaners cover all the equipment with plastic, I specifically told them to make sure no water gets into anything.

 

Here’s the thing I don’t get, I run the burner in service, it runs over 20 MA on high heat, it lights just fine, no odd sounds, no coughing it just lights it and runs but then for some odd ball reason it fails. It’s failed right at the beginning of a cycle and in the middle, there is no obvious pattern or specific time to it.

[fixbear]

The fact that you are experiencing multiple ovens doing the same thing tends to indicate a environmental problem with the ovens.  Like a air fuel mixture change.  Have you monitored the gas pressure over time?  Do you have a way to measure O2 near the burner intakes.  Again, before problem starts and as it happens.  If you are at a higher education facility, that teaches engineering, one of the lab’s will.

[olivero]

Okay, I’ll have to see. I have until about noon before they need it so I’ll go pull it now and see what I can get my hands on.

 

Could I use a small nylon brush to scrub it or is that a no-no?

 

Edit

 

The burner is in a bucket of Orbio now.

 

I guess we’ll see. I checked it with a flashlight first, I can see the light all the way around the mesh but I figured, why not try it.

[olivero]

True, but both ovens are not currently experiencing ignition failure, I also have plenty of other equipment that use the same style of burner that don’t have these problems. I got 3 kettles right across from these combi’s and they never had a problem other than the gas valve and some indicator lights.

 

I get what you are saying but it doesn’t strike me as a “common denominator” type issue we are resolving. It’s also just the top burner and not the bottom one that is throwing error codes.

 

Once again, I’ve watched the gas pressure for 30 minutes in the past, I’ve never had a problem with gas pressure on any of my equipment (other than it being too high) and I do think both burners would be having issues if it was related to that or some of the other equipment would as well.

 

These combi’s have a main gas valve on them and then an individual one for each burner.

 

So far, the only thing that’s made a difference in terms of error code frequency is replacing the igniter. 

 

I have a combustion analyzer that will measure O2, I am getting it later today and I can check whatever and wherever you think I need to.

[olivero]

Just pulled the burner, igniters is barely BARELY out of spec, 1 MM off on electrode distance but I do not believe that’s what’s causing this.

 

I am going to try to swap ignition modules from bottom to top and see if it changes anything.

 

I ran into a similar thing to this when my oven first had problems after we got it, I believe it was the first time it had problems.

 

Ecolab would come out, check the burner and saw the igniter was oxidized, so he replaced it, I think it was the same error code as the one right here, either for top or bottom. Then he checked the other burner and did the same thing.

 

Now error codes started to come for both burners, so he came back saw the igniters and changed them again, more error codes, came back and changed them again, and again until he had done this 3 or 4 times. 

 

Then they stopped. he deemed them as faulty igniters. He also changed both ignition modules at the time.

[fixbear]

At what point in all this did he calibrate the burners?

[olivero]

They were calibrated in May, before all the igniters were a problem according to my records. 

 

The igniter situation came up in June 2016, burners were calibrated in May 2016. 

[fixbear]

I don’t believe faulty igniters unless the part number changed. Plus there would have been service bulletin out on them.   On the 4th try he realized something was wrong and fixed it. Question is what.

[olivero]

You’d think there would have been a bulletin, but I don’t think so. I’ve seen some pretty interesting stuff with Convotherm that makes me believe otherwise.

 

I was with him the whole time he was working on the oven, as a matter of fact, he was asking me about most of it since he walked in and had never worked on one. 

 

In short, he changed both ignition modules, he changed the igniters multiple times. Adjusted overall inlet gas pressure to make it a tad higher and that’s it. He actually had me do the burner calibration with authorization from Cleveland as he didn’t have a combustion analyzer and the one they had needed to be recertified. 

 

I did have a theory pop into my head, what if the flame rectification is not happening properly, I am not sure what elements have to be in place before the flame can conduct electricity but from what i understand, the flame ionizes the gas around it and makes it able to carry electricity, what that flame needs to be is what I am interested in. 

 

I am going to read up on this stuff and see, perhaps the flame is not stabilizing the ionization of the air/gas around it and so the current can’t travel properly and so the signal loses strength and eventually dies away.

[fixbear]

That or the burner ground resistance changes with heat.