Harman TL2.6 issue

[TheRealProblem]

Hey guys,​

Having some problems with sustaining secondary, heck even achieving secondary burns, in my TL2.6. 2 year dry maple and poplar store outside. 13% moisture. 22 ft of chimney, stainless lined masonry. Stove will rumble then stall stack temps head towards 1100 f internal very quickly but no stable rumble lots of smoke and serious fear its going to trigger flue fire, had one last year cant really shake the fear. Never burned a downdraft before quickly regretting buying one. Any assistance would be appreciated

 

[begreen]

Welcome. These stoves can be fussy. They need good draft and dry wood and sometimes a prayer doesn't hurt either.
Can you describe the flues system on the stove from stove to chimney cap including any turns in the pipe?
How well seasoned is the wood?

 

[TheRealProblem]

Woods been drying for 2 years in piles was on landing for 6 mos. One 45 in pipe and one 90 to the thimble. About 5ft of double wall stovepipe to thimble. Stove whuffs badly if closed down without huge bed of coals. However if let to burn slowly it has so much draft that it takes nothing to run over 900. Really disliking the enormous stack temps to make this thing run. Seems like alot of wasted heat. Guy who sold me the stove said he doesnt want me burning wood over 15% moisture.....EMC here by the water is about 17.

 

[begreen]

Sounds like the stove is backpuffing. The 5 ft horizontal run is not helping. I'd change it so that the stove pipe goes up for a foot or so then gets a 45 to diagonally head to the thimble and then another 45 with a short horiz piece to the chimney. That will help draft. 17% MC is fine if it is being measured at room temp on the new face of a freshly split piece of wood.

What is the liner size inside the chimney? (clay or metal?) How tall is the chimney.

 

[TheRealProblem]

Sorry. Should have explained its only 6 inches of horizontal a 90 the 6 inch then 45 then 36 inches straight. Pipe is a stainless 6 inch seamless ( well riveted). Is 900 degrees in stack pushing 1100 after closing bypass really that safe though. Seems very high. Like chimney fire high

 

[branchburner]

Brand new stove, or used? Also, what is your technique for reducing the primary air once you have a good coal bed and close the bypass... are you knocking in back in 3 or 4 steps, or all at once?

And no, you really cannot close that bypass without a decent bed of coals to start. So the stove will get very hot (especially the flue) before you can close the bypass without stalling. Then the air has to be stepped back in stages, or THAT may stall the burn, also.. How long have you been running the Harman? It a long learning curve to get it just right, I'm afraid, but if this is a newer stove it should be possible. (If older, it may have a clogged combustion chamber.)

These stoves are best for 24/7 burning in the deepest cold, and they really get humming. In warmer times, they are a PITA, using a lot of fuel to get to clean burns if you are doing frequent restarts from few coals.

 

[TheRealProblem]

Brand new. Has seen no more than 2 cord of wood. PITA is right. Winter just has been cold enough to justify huge heavy burns. House is only 1200sqft and I cannot run it wide open without melting my cats, cats being liquid state at higher temps lol. Its just hard to shake the high stack temps in comparison to say an Enviro Kodiak etc. Fear I suppose gets the better of me and certainly makes me leery to push it much over 900 internal. Oh well soon it will be time to make next years wood supply and let the brute stove rest.

 

[branchburner]

Yeah, afraid these stoves run the flue pretty hot compared to most. But with good dry wood, I could get the secondary going and close the air down in steps to be nearly or fully closed. So it would cruise for hours with the flue external 250-350 (so internal 500-700?).... but before it would cruise, the flue before closing bypass would first routinely go over 1000f internal for a short time. But with the flue always running high, there was never a chance of touching off creosote... the pipe was pretty clean, maybe a few pints of fine brown powder at the end of the season.

 

[TheRealProblem]

Should mention. Finally got stove to cruise successfully. Thanks for easing my mind on the flue temps. Stove sustains temps in excess of 750 internal but will easily hold that for hours and produce an ingodly amount of heat. Now I am feeding a maple evaporator and let me say this, nothing burns wood like a maple arch

 

[MisterFixIT]

Issue sounds similar to what happened to my top loader/down draft stove. For the first 3-4 years it worked great, secondary would light up really quickly. Then over time it took higher and higher flue temperatures before I could close the bypass and get a secondary burn. If I did it too soon the primary would slow, the secondary would stop and I would have to open up the by pass to get it going again. Eventually I never ran the air control anything but 100% open.

> (If older, it may have a clogged combustion chamber.)

Yes, This is what I initially suspected. I have a ash vac and cleaned out the combustion package as well as I could but the issue did not improve. It was only until after I replaced it it that I found that the airway for the primary combustion was clogged up with ash. On my old stove the pathway is at the bottom of the stove right under the combustion package. It was way too easy for that to get blocked with ash and not know there was a problem. Also the combuster was very brittle which made it difficult to get at the primary airway to clean it without the combuster crumbling to dust.