flames coming out of flue

[techjoeb]

First and foremost I would avoid using the equipment at any cost until this issue is resolved. IT IS A FIRE HAZARD!!! So that being said, the rest of this is for really for informational purposes. I don’t know what your technical ability is and I don’t want to assume anything. 

 

1. Unspent gasses- this may be cause by incorrect orifices, partial lighting burners, high gas pressure or dirty burners. Basically the gas carries off and ignites in weird places because it can’t ignite where it is supposed to. 

2. Not enough oxygen- check the color of your flame. Is it orange or yellow instead of bright blue? That’s an indicator of low oxygen. The fact that it ignites in the flue is because that’s where it finds it’s oxygen to ignite. 

3. Grease in the flue. Yeah the grease isn’t supposed to ignite there but if it is caked in grease it’s plenty of fuel for the flame to make it all the way up there. 

4. Not enough positive air- yeah this is similar to the oxygen thing BUT there is nowhere for the gasses to go. It’s only hitting the flue because warm air goes up. You need some positive ventilation to ensure there there is supply to move up and out. You don’t want a vacuum situation. 

 

So I know this is a big list and it’s not all inclusive but it should give you some things to check to get an idea of what the issue is. I strongly recommend to STOP USING THE EQUIPMENT because you will start a fire. My two cents. I hope this helps. 

 

-Joe 

[olivero]

Hey Joe,

 

I service commercial equipment for a living, so there is no problem getting into it with me.

 

IT is not as bad as it sounds however I can put it. The flame is barely visible and mainly occurs once the initial ignition occurs at the burner. I have checked the gas pressure and its what the equipment is rated for. It seems to only do it occasionally, not constantly. The burners venturial settings in terms of the mix of primary air and gas has not been adjusted since the equipment was originally installed so it leads me to the vent limiter perhaps playing tricks on the regulator again, seems whenever the relief hole in the limiter gets clogged with grease and what not, strange things happen. 

 

The unit is under an exhaust hood with make up air so there is plenty of air.

 

I am going to take it out and clean it up and see what happens.

[techjoeb]

 I’m glad you know how to handle these issues. It was more of a general response in case someone finds this post searching the internet. Please let us know what the issue was. I would love to know the outcome. Good luck! 

 

-Joe 

[fixbear]

propane or natural gas? Pre or after 2010?

[olivero]

Hey Joe,

Appreciate you stepping in to help me out. Very true, in most cases a proper evaluation cannot be done by the users, I see it too much with people thinking it will be okay when its really a severe hazard.

 

I removed the vent limiter and boiled it out now its not doing this odd stunt anymore. 

 

I guess I should have done that to begin with but figured I would ask around here first.

[olivero]

Natural gas, after 2010.

[davejohnsonnola]

Different equipment, but remided me of a situation…in our case it was a Pitco fryer that had had a rushed intent at deep cleaning.  Grease scrapings fell down into the flue and scared the beejeezus out of the opening crew when it caught on fire.

[sp21500]

I have checked the service manual, and there is no reference to this condition, although the 1st thing that comes to my mind is the Make Up Air system in the building. It might be possible that there is times of the day in which the MUA is stronger than other times, and therefore draws the flame up into the overhead ventilation.  This might explain the intermittent times, and flame height.

Regarding the unit itself, the manual clearly states that the Gas Pressure Regulator MUST be installed as close to the griddle as possible to avoid pressure related issues. Furthermore, it is recommended to make sure the Vent on the Pressure Regulator is clean and not obstructed.

[olivero]

Right, I checked those things but since I have 2 right next to eachother under the same hood, if it was a MUA issue, I should be seeing it on both units.

 

The problem did not exist when first installed so any of the original installs like the regulators and gas pressure have not changed so it would have to be something gone wrong recently, in this case it was solved with the vent limiter being clogged so after cleaning it up, the issue resolved.

 

Thank you for looking I do appreciate the effort.

[olivero]

Right, I have heard of people moving equipment into the airflow of the make up air system, in which case the air was blowing right down the flue and flames started coming out the front of the equipment. Sometimes its a stupid problem and sometimes, its simple.

 

In this case it was simple, grease droppings can definetley scare the beejeezus out of people. I once got asked to help weld a griddle/salamander unit back together as the grease tray on the griddle cracked and right below it was a salamander, it was one of those combo units. The grease would drip through the track and directly onto the burner and it made it difficult for the chefs to cook at times

 

Welded the crack up and it fixed it but I know what your talking about