# LP Fuel Fire Pit Problem



## jpf5911 (May 11, 2007)

I have a new outdoor firepit that runs on fuel from an LP tank.

The valve/hose from the tank leads to a fitting on a bowl that is filled with lava rocks and ceramic logs.

When I use the firepit, it works fine for about 15 minutes, then it occasionally pops and eventually will hiss loudly without stopping.

I have used two different tanks and get the same results.

Any ideas?

Thanks,

JPF


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## bacsales (May 11, 2007)

It sounds like the regulator is not right?  The roaring noise is probably the gas igniting inside the burner tube.  This is not good.  Get the unit serviced or replaced asap.


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## berlin (May 12, 2007)

not possible for the gas to ignite inside burner tubes, UNLESS, there is very low pressure, ie. regulator, what is also common is propane being heavier than air sometimes sits, uncombusted in the bottom of the pit untill it finally ignites, this can happen with some frequency causing "pops" and other annoying noises.


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## jtp10181 (May 12, 2007)

berlin said:
			
		

> not possible for the gas to ignite inside burner tubes, UNLESS, there is very low pressure, ie. regulator, what is also common is propane being heavier than air sometimes sits, uncombusted in the bottom of the pit untill it finally ignites, this can happen with some frequency causing "pops" and other annoying noises.



It is very possible... I have seen it many many times on LP Direct Vent fireplaces.


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## berlin (May 13, 2007)

no, it's not possible, unless you're getting air inside the tubes, which doesn't happen because of the positive pressure inside the tubes; however you can get air inside the tubes if the regulator is not allowing enough pressure, this can cause mixing of air/fuel inside portions of the tube with almost no positive pressure, thus the reason for what i mentioned without fully explaining the details. other than this gas will not burn w/out oxygen period.


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## jtp10181 (May 13, 2007)

Most burner tubes have an air shutter which allows air to mix with the gas just as it leaves the orfice. Usually on LP it is wide open. I have seen it happen with good pressures, you cannot tell me its impossible.


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## BrotherBart (May 13, 2007)

berlin said:
			
		

> no, it's not possible, unless you're getting air inside the tubes, which doesn't happen because of the positive pressure inside the tubes; however you can get air inside the tubes if the regulator is not allowing enough pressure, this can cause mixing of air/fuel inside portions of the tube with almost no positive pressure, thus the reason for what i mentioned without fully explaining the details. other than this gas will not burn w/out oxygen period.



Help me out here berlin. Virtually every gas burner I have ever seen mixes the air and gas via venturi prior to it entering the burner tube. Why would it not be possible for this mixture to burn in the tube? Inquiring minds just gotta know.


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## elkimmeg (May 13, 2007)

Want to bet this guy has gas mites or spiders or spider webs in his gas line?  My suggestion to him is to borrow a know working line and regulator 
and install it to see if your problems dissapear


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## MountainStoveGuy (May 13, 2007)

90% of the grills i go out and service have this issue. The valves are toasted, or the nobs are melted, or the ignitor button is toasted, all of these are caused by spiders in the venturi tube and a back burn out of the venturi tube. Not only is it possible, its common.


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## berlin (May 14, 2007)

"Help me out here berlin. Virtually every gas burner I have ever seen mixes the air and gas via venturi prior to it entering the burner tube. Why would it not be possible for this mixture to burn in the tube? Inquiring minds just gotta know."

here's how it's not possible; i have yet to see an outdoor firepit burner that premixes the air/fuel. not saying they don't exist, although i doubt it, because the purpose of outdoor firepits is to view the flame which requires no premixing of the air/fuel to obtain that wonderful yellow color. usually it's one or two rings of tubes with gas coming in from the bottom covered by lava rock to diffuse the gas more; all mixing of air/fuel takes place outside the tubes.


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## BrotherBart (May 14, 2007)

berlin said:
			
		

> "Help me out here berlin. Virtually every gas burner I have ever seen mixes the air and gas via venturi prior to it entering the burner tube. Why would it not be possible for this mixture to burn in the tube? Inquiring minds just gotta know."
> 
> here's how it's not possible; i have yet to see an outdoor firepit burner that premixes the air/fuel. not saying they don't exist, although i doubt it, because the purpose of outdoor firepits is to view the flame which requires no premixing of the air/fuel to obtain that wonderful yellow color. usually it's one or two rings of tubes with gas coming in from the bottom covered by lava rock to diffuse the gas more; all mixing of air/fuel takes place outside the tubes.



Ah. Thanks. Hadn't ever seen one of the things.


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## river rat (May 14, 2007)

yes gas fire pits have round burners  but if it is lp it needs a venturi to mix gas and oxygen . venturi would be located before stainless steel burner. lp cannot be burned clean without air mix venturi. Natural gas does not require air to be mixed. All lp fire pit have a air mix venturi. Natural gas not. Burning lp without mixing air would  just carbon everything up. Yes could be spiders in burn tube. They could have entered  through air mix venturi.


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## river rat (May 14, 2007)

http://www.thecustomfireplace.com/fipitrereand.html


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## Gooserider (May 15, 2007)

The OP says the pit is NEW - which IMHO would tend to rule out spiders and such.  OTOH, I wonder if there is any chance that the wrong orifice was installed in the burner such that he is trying to run with a Natural Gas orifice instead of the proper LP orifice?  (I'm not a gas person, so I'm not sure what the symptoms of this are, but it's the first thought that occurs to me, and nobody else has mentioned it...)

Gooserider


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## MountainStoveGuy (May 15, 2007)

Berlin is right about most ring burners, FWIW, there are lots of other types on the market that do have shutters. The weber, the omni firepit, the heat-n-glo patio campfire, and more pre mix air in a venturi before the burner. I would guess that this guys firepit has a airshutter, and its mixing to much air, or he has a defective regulator, or both


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