# LP Issue...WTF?



## DAKSY (Dec 15, 2012)

Normally, I'm in this forum trying to help folks with their gas units, as I was a service tech for a number of years. I have two of them myself, & I usually service them every other year - vacuum, paint, replace ember material, polish the glass, etc., & this is one of the "off" years. Well, wouldn't you know it, my HnG 6000TRXI stated to act a little funny. looked like the right side rear "flame-in" log wasn't burning at the gas ports. There DID seem to be a large flame at the burner orifice...WTF? So I went to remove the glass & the upper right latch was unhooked...WTF? I took the glass off & realized that the entire right side of it had a sooty coating...WTF? I pulled ALL the logs & the entire burner tube in the log was CLOGGED with soot!...WTF? I disassembled the tube from the log & of course the gasket material disintegrated once it wasn't constrained. I'm telling ya there was soot everywhere! I brushed everything down with a soft-bristle brush & I found a tube of RTV to use to replace the gasket & reassembled the logs & cleaned the glass. All good to go. First time I have EVER seen a burner port TOTALLY Clogged with soot. guess I'm gonna start going to an every year service... Kinda feel like the mechanic who drives the biggest POS in town...


----------



## ScotO (Dec 16, 2012)

Daksy, what would cause the soot, especially after one year since it was cleaned out?  Did they change the make-up of LP?


----------



## EatenByLimestone (Dec 16, 2012)

Incomplete combustion... did you close up the air intake towards the NG setting by accident when you cleaned it last time?  There could be extra contaminants in the gas, but you would have noticed it on the stove and other heater if that was the case.  

Matt


----------



## DAKSY (Dec 16, 2012)

Scotty Overkill said:


> Daksy, what would cause the soot, especially after one year since it was cleaned out? Did they change the make-up of LP?


 
Incomplete combustion or inadequate O2 are the MAIN causes for soot. To be honest, Scotty, I never looked inside the logs before. I pulled them & bushed them off, but never addressed the burner tubes, as there had never been an issue. Lesson learned. The Original LP company got bought out by a bigger concern, but I don't know that the LP or its additive mix had been tinkered with...


----------



## DAKSY (Dec 16, 2012)

EatenByLimestone said:


> Incomplete combustion... did you close up the air intake towards the NG setting by accident when you cleaned it last time? There could be extra contaminants in the gas, but you would have noticed it on the stove and other heater if that was the case.
> 
> Matt


 
No adjustment allowed on these "in-burner logs" Matt. The air shutter is simply an open slot on either side. In order to be convertedfor a fuel change, the logs must be changed...


----------



## Todd 2 (Dec 16, 2012)

Daksy, I have run into this myself a time or two in the past, HVAC trade for to many years, ha.  Took everything apart possible and cleaned for people and worked great after that, never really could pinpoint what the cause was, and didn't hear of the problem again from them. Tank & gas valve water column meter pressures right on along with everything else normal. I still think it had something to do with the LP, if my memory serves me right I think it happened within a short time after fills.     ?      Todd


----------



## Fake coal burner (Dec 16, 2012)

I had that happen 2 weeks a go on my Natural gas coal affect stove. I just cleaned every thing the prior month. It was all soot cleaned glass fired it up after 1 day of running soot high or low. Took every thing apart again got a magnifying glass and looked at the burner strip and found a piece of carbon in it. Had to run a feeler gauge along flame strip to get it out. Vacuumed ever thing out put it to gather again. Air shutter is wide open as should be. Works like a charm now. Door opens like on a wood stove make it easy to service. The flame makes contact with the coals and they glow as flame moves all around and under them..


----------



## Ironhorse74 (Dec 17, 2012)

Daksy there is some real hot propane out there. I have seen some of it clocked at 130k btu per gal. Engineering says it is a problem with too much methane. The propane suppliers add methane to dry the tanks. Just thinking out loud here. Hot propane means not enough O2

Something to think about

Brad


----------



## FanMan (Dec 18, 2012)

Ironhorse74 said:


> The propane suppliers add methane to dry the tanks. Just thinking out loud here.


 
I think you mean methanol (methyl alcohol), not methane.  Methanol (same as the "dry gas" you put in your car) is supposed to be added to a new tank to absorb any residual moisture.


----------



## coaly (Dec 18, 2012)

First, appliances usually work until something is changed, in this case the latch allowing combustion gasses to leak in, not rising through the exhaust and preventing barometric air pressure from pushing into the intake. (Expanded gasses rise out, barometric air pressure takes up the void allowing oxygen into burner) Not sure about your particular appliance, but think about the latch that was unhooked, and what that does to air flow / exhaust and or barometric pressure needed to push the air into the intake of the main burner. Obviously it was an incorrect rich mixture, probably starving for oxygen.

Height of exhaust vent is critical on some direct vent appliances to get the correct draft to cause this negative pressure required to allow atmospheric pressure to get in. Opening the glass is going to affect the flow even more.

#2, I would put a manometer on the test port of the valve at the appliance, (or tee into line with a test port) and see what pressure you have with main burner lit. Sometimes you will see a fluctuation in pressure, which is a heavy oil in the line. The gas vapor gurgles through traps in the line that are full of this fluid. Usually with older tanks, I've had pressure drops when it's cold due to the fluid thickening. I've pulled many lines apart, and blew out with compressed air (back towards the disconnected regulator) and found a LOT of this stinky oil residue came out.
Another cause, not so much with newer units with double shut off valves, is if a control valve doesn't shut all the way, the little gas that comes out is just enough to ignite at the oriface and burn like a small match. Any flame at the oriface is burning raw fuel, not mixing with oxygen and will build up soot fast. Next time the valve opens fully, the soot in mixing tube is enough to prevent air getting in the burner and it snowballs. Sootballs in this case. I've seen what looks like huge black wasp's nest on the glass. That only happens with a customer with white carpet........
Retired from my own LP service business in 2008, but it all comes back quick!


----------



## TK of SC (Jan 10, 2013)

Daksy, I've seen this when burn back occurs.  LPG burning inside the burn tube, usually associated with the carb being just slightly too open for the type of LPG being burned.  I know that sounds crazy to close an LPG carburetor just a bit, but its worked on many occasions.  When I say type of LPG, I'm referring to the little talked about fact that every tank fill is for sure a different mix of chemicals and gasses.  As long as it meets the Federal standard of 90,000 btu/gallon, I understand it can be made up with a variety of components ( read: what ever s cheapest and most available in the open market).
Tom


----------



## DAKSY (Jan 10, 2013)

TK of SC said:


> Daksy, I've seen this when burn back occurs. LPG burning inside the burn tube, usually associated with the carb being just slightly too open for the type of LPG being burned. I know that sounds crazy to close an LPG carburetor just a bit, but its worked on many occasions. When I say type of LPG, I'm referring to the little talked about fact that every tank fill is for sure a different mix of chemicals and gasses. As long as it meets the Federal standard of 90,000 btu/gallon, I understand it can be made up with a variety of components ( read: what ever s cheapest and most available in the open market).
> Tom


 
No adjustment on the HnG in-log burners. Air shutter is Mfr'd wide open...


----------

