The term “TLUD” originated in 2005, hence it will not be found in the earlier writings. It’s an acronym for “Top-Lit UpDraft” – a descriptive phrase first used in 2004 to name the process of micro-gasification for which this website is dedicated. “TLUD” is hard to pronounce if read as a word, but in August 2005 at a Stove Camp, David Penise coined a much easier pronunciation by reading it as “T-LUD”, as in “tee-lud”. Today, we write the name without the hyphen, as in TLUD, but pronounce it as if the hyphen were there.
The term “inverted downdraft” (IDD) was used for many years by Tom Reed, the acknowledged originator of controlled top-lit updraft (TLUD) gasification. While technically accurate, the concept of an inverted downdraft was difficult to explain.
Note about TLUDs: Once the fire has reached the bottom (at the end of pyrolysis or if the fire drops down too quickly throught excessively large gaps), the device is no longer operating in the “TLUD mode” that has the actively descending pyrolysis front. It is then a bottom-burning fire, akin to a bucket fire that is ignited at the bottom. The “mode” changes inside of the same stove. And the emission levels change, etc.
Therefore, the ability to add additional fuel while the stove is burning does not automatically mean that it is operating in the TLUD mode. What is happening to the newly input wood is that it is being pyrolyzed by the heat that is coming upward. That can be a form of micro-gasification (pyrolysis from heat without oxygen present — as in a retort — without the arrival of the small amount of oxygen as occurs in the TLUD-specific migrating pyrolysis front). Therefore, it is not the same as the physical-chemical processes in the downward migrating pyrolysis front.
TLUD refers to a process of “”top-lit updraft with migrating pyrolysis front”, and when that front stops moving at the end of the batch process, the mode or regime of the fire changes.
Both TLUD and IDD (and their corresponding words) refer to a method of combustion that is essentially pyrolytic gasification of dry biomass, followed by the combustion of those gases, with a co-product of charcoal (char) that can be saved or combusted. TLUD and IDD are public domain terms that describe a method or process. They are not the names of a specific stove or device, as there can be many TLUD-style devices.
The term “stove” refers to an object or structure in which heat is created and used for cooking. Therefore, a TLUD stove is one that utilizes the TLUD gasification technology in a stove structure. Likewise, there can be TLUD water heaters, TLUD fruit driers, and other application devices in which the TLUD technology is used in the creation of heat.
The name “Juntos” is the trademark of Paul S. Anderson’s stoves.
The name “Champion” has been taken as a trademark name for the specific TLUD gasifier stove that won the award for the cleanest combustion at a Stove Camp in 2005.