MemberMarch 26, 2018 at 12:00 am
Well, Another one to solve.
Top burner ignition failure. Top is 1, 2 is boiler (don’t have a boiler on this one), 3 is bottom.
This one was first looked into because there was a loud gunshot noise coming from the oven, turned out it was the top burner when it lit. I pulled the burner and this is what the igniter looked like.
Spoke to Convotherm tech support and was instructed to replace the igniter, did that as well as their 25 minute on high heat “burn in” period to prevent premature warping. 2-3 days later the same error code occurs, I pull the burner again.
It’s warped, so I replace the igniter again thinking this one was just a faulty part. 2-3 days later, same error code appears. Looks like the above picture but less warped and so I realign everything, check gap and bring the electrodes back in level like Convotherm specifices. Check all the electrical connections on the ignition module and the combustion blower, check that the combustion blower is spinning freely.
Next day the same error code appears, I don’t hear about it until 2-3 days later when its happened 2-3 more times. pretty much daily now.
Trying to get some help from Convotherm but its taking time that I don’t have, this unit keeps being a problem despite all the work that’s being put into it.
Any idea what it could be other than the igniter? Perhaps something is wrong with the igniters? These are spark style.
Could the ignition module be going bad?
MemberMarch 26, 2018 at 4:47 pm
My first thought:
- Maybe some blockage of the burner’s metal mesh is causing undesirable flame characteristics.
Have you ever cleaned those burners? If not, then I suggest that. That’s a major step closer to getting the burner back into virgin condition.
MemberMarch 26, 2018 at 4:49 pm
I checked that when I pulled it, it is pretty clean, I shine my light through it and I can see the light through the mesh.
Unit’s only 2 years old.
I could pull it again and double check. Unfortunately with the Convotherm 4 they removed the inspection glass they had on the former model that at least would let you look into the burner compartment so you could see what was going on.
Just getting tired of pulling this burner out.
MemberMarch 26, 2018 at 5:13 pm
question #1: do you have a combustion analyzer?
question #2: what is your static and dynamic gas pressure for this unit?
question #3: what is your elevation?
question #4: LP or nat. gas?
MemberMarch 26, 2018 at 5:15 pm
Yes, I know what a PITA that is to pull those burners.
Allot of kitchen vapors and such can get sucked in there after two years.
Put the burner in a bucket and soak it with some general purpose cleaner like Spray Nine, Fantastic or whatever you got. Rinse, blast with compressed (blowing from outside in), let air dry and put it back in.
Also check and clean the air inlet hoses and the burner blower too.
How is gas feed to the burners adjusted on the Convotherms. Using a combustion analyzer?
MemberMarch 26, 2018 at 5:16 pm
There ya go. Good questions.
MemberMarch 26, 2018 at 5:29 pm
Lol, they got some odd new design to keep it on there, this “smart clip” that’s darn near impossible to get back on while holding the burner (alone, that is)
Do I need to check it again first? How do I know if its clean? I’ll have time tomorrow morning to pull the burner again and they will be using it for the rest of the day, so its plotting time.
“How is gas feed to the burners adjusted on the Convotherms. Using a combustion analyzer?”
MemberMarch 26, 2018 at 5:34 pm
1: Yes, we have one here. these are the readings from May 2016, when both burners were calibrated with Ecolab (unit was under warranty still)
Min Speed Max Speed
02: 3.7% 02: 3.4%
CO:20 PPM CO: 29 PPM
Eff: 83.8% Eff: 76.7%
CO2: 10.1 % CO2: 9.9%
Temp: 307*F Temp: 616 *F
Co (o): 22 PPM Co (o) : 35 PPM
Min Speed Max Speed
02: 3.1% 02: 3.4%
CO:18 PPM CO: 29 PPM
Eff: 84.8% Eff: 76.7%
CO2: 10.1 % CO2: 10.3%
Temp: 307*F Temp: 616 *F
Co (o): 22 PPM Co (o) : 35 PPM
These are the original readings, they were dialed in afterwards, I can’t find the numbers from when it happened, it was done with Ecolab.
2. 5.1″ W.C dynamic with burner on high, that’s on the inlet side of the gas valve, not manifold side. 6.4″ static.
3. according to google, its 30′ (clearwater, FL)
4. Its Natural Gas.
MemberMarch 26, 2018 at 5:40 pm
Those are great readings to have. I find it helpful to leave that documentation inside the control panel where it can be used for comparison purposes. Which will lead me to question #5: what are your combustion readings TODAY ? look for some kind of a change to lead you to the excessive heat at the ignitor area. Additionally, is it at all possible that something could have fallen into the flue outlet for the heat exchanger? Even small bits of foil, loose hardware or water from hood cleaners can cause funky back pressures within the combustion chamber.
MemberMarch 26, 2018 at 5:46 pm
How do I know if its clean?
You’ll know when you immerse the burner in the cleaning solution I’d suggested. Check it twenty minutes later and you’ll have an adequate visual cue that you’re making progress. The solution will have turned brownish.
I don’t remove and clean our burners on a regular basis. However, when I have to pull one, I clean it before putting it back in. I have some tech literature from Rational explaining to do this. The method I use is simply mine.
MemberMarch 26, 2018 at 6:29 pm
Your picture shows that the flame retention -anti flashback mesh has had a very high heat. Like the flame was inside it instead of one the surface. O hole to large somewhere?
MemberMarch 27, 2018 at 8:35 am
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.
MemberMarch 27, 2018 at 9:09 am
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.
MemberMarch 27, 2018 at 9:11 am
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?
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.
MemberMarch 27, 2018 at 9:21 am
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.
MemberMarch 27, 2018 at 9:31 am
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.
MemberMarch 27, 2018 at 11:03 am
At what point in all this did he calibrate the burners?
MemberMarch 27, 2018 at 11:36 am
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.
MemberMarch 27, 2018 at 11:50 am
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.
MemberMarch 27, 2018 at 12:09 pm
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.
MemberMarch 27, 2018 at 12:50 pm
That or the burner ground resistance changes with heat.
MemberMarch 27, 2018 at 1:02 pm
I guess it’s possible.
Just wouldn’t know what to do about that.
MemberMarch 27, 2018 at 1:39 pm
Okay, so here is what I am seeing.
I pulled the burner, igniter gap is good, not much wrong, cleaned the burner, swapped modules and here is what I see.
The top burner is loosing its MA signal, or its growing weaker and weaker by the minutes. It starts out at 30 on full heat, then slowly drops down and keeps dropping, it went down to 8 MA whereas the bottom burner stayed strong on 30 or above and didn’t waver. I was monitoring gas pressure at the same time as this, it was holding 7″ W.C strong and the MA signal was still dropping.
When I originally changed the igniter the first time (in this chain of events) the MA signal was doing the same thing and kept dropping until it hit 0 and the burner would relight and start over, that’s why I changed the igniter again but It’s doing the same thing it seems.
This is reminding me of the last time with the faulty igniters, I believe we were seeing similar things.
Tried to use the combustion analyzer but the 02 sensor is used up and doesen’t work so it’s not much good.
CO is 18 PPM for both top and bottom burner, not much good without all the other measurements but that’s all It’ll do right now.
MemberMarch 27, 2018 at 2:17 pm
Clean bright connections. cotton gloves when handling the electrode. Especially the outer 90 degree one to prevent body oil from making a track or oxidation point. Fresh screws and star locks help. It has to ground through the burner, so it to has to be clean at retaining points.
MemberMarch 27, 2018 at 2:21 pm
Just got off the phone with Convotherm, apparently they now have a Gen III igniter and I am using Gen III so they are advising I change to the new style and update my software and that should take care of it.
MemberMarch 27, 2018 at 2:34 pm
Makes sense, I’ll keep it in mind.
This igniter only has 1 wire, I wonder how it travels back to the ignition module. Could they be using the same wire for spark ignition as they are for monitoring MA signal?
MemberMarch 27, 2018 at 3:12 pm
Normally the sensing is done through the burner ground. But, this machine has a dedicated special built burner control. Wiring diagram on it is a bit vague.
Now I noticed that the electrode wire has a either resistor or diode in the middle. Be nice to know which it is. If you have a old one yet you could cut off the heat shrink to see. It should have a NEC number or colored bands. Ohm it out and check vs. a new one. Semiconductors are very sensitive to heat, So routing of that wire may be critical if a diode..
MemberMarch 27, 2018 at 3:24 pm
MemberMarch 27, 2018 at 7:17 pm
22 ohm resistor. They must have had some interferance to there controls at some point.
MemberMarch 27, 2018 at 9:14 pm
Could very well be.
Got 2 of the Gen IIII igniters coming from Convotherm, will be here tomorrow morning. I’ll snap a picture of them so you can see the new one.
MemberMarch 28, 2018 at 8:55 pm
MemberMarch 29, 2018 at 7:48 am
So basically what you are saying, Actually what Cleveland is saying, is that they have a design problem that failed to take expansion into consideration.. Noticed that they not only reinforced the insulator, but added a expansion curve in the electrode.. So next the porcelain will break. The fuel-air tube and the electrode are different alloys. With very different expansion rates. Having a 90 degree electrode is never a good idea unless it can float.
The only way I can see this problem going away is a total burner redesign. My personal opinion..
On a side note, wonder if anyone has done a cost of ownership to a gas vs. electric version. The gas seems to have a lot more service calls.
MemberMarch 29, 2018 at 1:45 pm
Been nothing but hit and miss on this thing so far.
Well, that was short lived; Came in this morning, E05.1.8 strikes again, twice this morning.
So now what?
Now they are giving the problem to Convotherm in Germany to try and solve. Guess we will see. Sent over the entire error log and HACCP data so hopefully that will give them an idea.
MemberMarch 29, 2018 at 2:11 pm
I’m betting that they tell you to change the burner.
MemberMarch 29, 2018 at 4:00 pm
They very well could. I am hoping they tell me the tracking number for my new oven.
MemberMarch 29, 2018 at 4:43 pm
I’m thinking ignition module. What’s the wager?
MemberMarch 29, 2018 at 5:04 pm
I’ll save you some money and let you know I already swapped the 2 modules and it made no difference.
MemberMarch 29, 2018 at 5:24 pm
DAD-gummit! This thread is too long. I forgot what all you’d done!
MemberMarch 29, 2018 at 5:31 pm
Haha, I know, probably the longest one on Tech Town.
I actually got on the phone with a German Convotherm tech in Germany today, I dealt with him in the past when a transistor burnt up on the main board….. Grr… anyways, told him a bit about what was happening and I’d sent him an email listing all the problems I knew about and he said he was going to talk to his superiors and see about getting the whole darn unit replaced. Then I sent him the actual error log and everything I could export off the unit.
Now that’s tech support at its finest.
I’m so done playing games with this unit, The gun range sounds like it might fix it. permanently.
MemberMarch 29, 2018 at 6:13 pm
MemberMarch 29, 2018 at 6:43 pm
Hope you shared the original igniter pic you took
MemberMarch 29, 2018 at 8:19 pm
being you are in TN, olivero is in FL, andi’m in NY I’m not sure. However, if they ship him a new oven and we are going to blow up the old one. a road trip has to be planned.
MemberMarch 30, 2018 at 8:36 am
That’s awesome. I showed it to my office and the chefs, they all burst out laughing.
MemberMarch 30, 2018 at 8:37 am
I did, sent them everything I found.
MemberMarch 30, 2018 at 10:45 am
You guys crack me up.
I am planning on going through the whole unit again tomorrow morning, just take it from the top and make sure I didn’t miss anything stupid.
MemberMarch 30, 2018 at 7:12 pm
>being you are in TN, olivero is in FL, andi’m in NY I’m not sure.
>a road trip has to be planned.
Count me in, from Georgia! Today’s my last day, I can be anywhere in the country in a few days.
Looking through everything, again, I keep thinking that you’ve got too much flamage going on. I mean you know how hot it needs to be to warp the ignition electrode set like that? And you are getting 30 microamps; the Rationals see like 5.25 or so, and it’s the exact same style burner, very similar ignitor/gnd set. It seems like it’s not burning at the surface of the the burner mesh, but up about an inch or two higher than it should.
I say this because we got a bulletin from Rational to drop the max fan speed setting (=btu input) to it’s minimum setting the computer allows at each unit we visit, on the air heat. Stop em from burning out so much?
If it were my unit, I’d either tape over half of the burner blower air input hole, and run it like that for a while, or if the software permits, reduce the high fire blower speed to drop those btu’s down.
MemberMarch 30, 2018 at 7:33 pm
>22 ohm resistor
Naa, that symbol is “u” for micro (farad? capacitor?), not the, ah, omega (?) ohm symbol.
MemberMarch 30, 2018 at 8:22 pm
Lol, the computer does allow to drop the RPM’s of the combustion blower which would reduce the BTU input I guess.
I would need that said through Convotherm though. The thing that I don’t get is that its been working somewhat okay throughout periods of time so for me to change something that’s been a certain way since day one to solve a problem I am seeing now doesn’t sound right to me.
MemberMarch 30, 2018 at 8:23 pm
Interesting. A Capacitor…. I wonder why.
MemberMarch 31, 2018 at 9:59 am
Not a capacitor. They can’t make a cap out of ceramic due to the high heat needed to fuse the ceramic. After much searching, it is a 22 micro ohm 4.3 amp resistor.( real low resistance) rated at 200 C. Very very special value for a micro.ohm resistor.. Anything with a higher resistance would bother a milliamp current flow for the burner control.
And my eyes are going cross from all the 100’s of thousand passives I had to go through to find it.
MemberMarch 31, 2018 at 10:02 am
The heat required to soften near melting of a electrode got to be up there. like you said, the tip of the blue had to be right at the igniter. Wish I knew what alloy the rods are.
MemberMarch 31, 2018 at 3:21 pm
Yeah, I think they are Tungsten, not sure though.
I added an additional wire between the burner flange and the combustion blower/Gas valve mounting screws, now it holds over 30 MA in service so its an improvement, we will have to see if it handles the intermittent problems.
MemberApril 3, 2018 at 7:01 am
Been 4 days with the ground wire. Any problems?
MemberApril 3, 2018 at 8:47 am
Been happy so far.
I thought about doing this starting out, I just have had some pretty bad experiences with my first options being modifying how something is built or how its configured. Its worked before, its also made stuff crash even harder so I try to leave adding new things or modifying things, to a last resort unless the OEM is saying to do it.
Even if this does solve it, I think the underlying problem of why the ground is lost is still there and should be resolved, it just proves that that’s the problem.
MemberApril 3, 2018 at 6:19 pm
Good for you.
I can’t recollect the number of times I’ve seen when poor flame proof…proved to be a poor ground. Easy to overlook and, even though I know you’d thought of it, I guess the manufacturer who designed it…DIDN’T.
MemberApril 3, 2018 at 7:00 pm
Yea, its a shame it has to be re-solved like this.
Here’s a new one, just got told the oven was making a loud *woooooo* sound when it was running, it was steaming and heating so when the chef opened the door, it shut off.
Burner harmonics, now I have to figure out which burner and hopefully it will be simple to solve.
MemberApril 3, 2018 at 7:19 pm
That would go along with the lack of flame retention that melted the first igniter.
MemberApril 3, 2018 at 8:02 pm
I am thinking igniters are misaligned or something. I’ve already verified gas pressure and flue analyzer and everything is in order, Its coming from the bottom burner though, not the top. I am going to try to pull the burner tonight and get a good look at it.
MemberApril 3, 2018 at 8:28 pm
allright, THIS deserves a what the heck.
I go to pull the bottom burner and as I loosen the last nut WATER comes out! WATER.
We just had our hoods cleaned last night….. I wonder……………..
MemberApril 3, 2018 at 8:33 pm
Steam in the burner will do it every time. LOL
MemberApril 3, 2018 at 9:03 pm
Does it? Does the steam cause that odd woom noise?
I thought about it some more, the odds of that water making 2 full circles in the heat exchanger and landing on the burner is pretty unlikely. MORE likely, there is a crack in the heat exchanger somewhere.
Luckily for me, I have a bottom heat exchanger on the shelf. Well, floor, its too big to fit on the shelf.
MemberApril 4, 2018 at 4:42 am
Let’s think about this for a moment. Water in the burner? Vertical circular heat exchanger? Not a boiler, so that rules out a heat exchanger crack. High moisture cooking chamber, Doesn’t matter as the heat exchanger is hotter than the oven and water would not condense. What does that leave us? Water ingress to the blower suction! Finding it may be the problem. If you have a water line downstream of a solenoid, Good luck It could be no more than a drip that accumulates in the lower section till it get’s pushed up the the venturi.
And yes, water in a combustion area will cause some weird sounds as it flashes to steam. It will also modify the flame. Had some experience with that in heating systems after a flood.
MemberApril 4, 2018 at 11:35 am
Considering the unit had just finished a cleaning cycle which is not done very hot, it would make more sense for that water to have made it into the heat exchanger through a crack rather than it sucking up water through the venturi which is not even close to any surface, its a tube sticking out into the air, other option is water in the gas, but I think that’s pretty much a given that, that ain’t it.
In an hour and some time, I’ll know for sure.
Just finished the cleaning cycle, pulled the burner again and water came out. Going to pull out the heat exchanger now.
MemberApril 4, 2018 at 12:22 pm
MemberApril 4, 2018 at 3:28 pm
What are they using that is eating the metal?
MemberApril 4, 2018 at 4:08 pm
They are only using the convocleaner products, nothing else.
I don’t think the heat distribution on the metal is even, it seems to be more in the top than bottom.
MemberApril 4, 2018 at 4:41 pm
MemberApril 4, 2018 at 8:28 pm
Too hot.. Heat errosion then.
MemberApril 4, 2018 at 8:37 pm
Yeah, that tubing could have probably been an inch or 2 wider right at the beginning, doesen’t seem right its glowing red when the burner is on full blast with the fan on. I could understand it and the previos model is like that where if the fan is NOT spinning, then it glows red. But can’t be good for the stainless to be heated THAT much.
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