Some super efficient stoves from down under

[begreen]

I've been perusing through ULEB stoves in New Zealand. Some achieve exceptional results. They have several variations on the Wittus Twin-Fire concept that are ultra clean burning and efficient. These stoves are testing much cleaner and more efficient than high-efficiency pellet stoves.
https://www.tropicair.co.nz/product/duo-uleb-by-tropicair/
https://www.ferva.co.nz/

Here's the authorized stove list in NZ
https://www.ecan.govt.nz/data/authorised-burners/

 

[Happy Stacker]

Couple neat features I like on the Ferva Saturn. The bypass is automatically engaged when the front loading door is opened. And the built in USB charging socket using a TEG generator.

 

[Ctwoodtick]

I've been perusing through ULEB stoves in New Zealand. Some achieve exceptional results. They have several variations on the Wittus Twin-Fire concept that are ultra clean burning and efficient. These stoves are testing much cleaner and more efficient than high-efficiency pellet stoves.
https://www.tropicair.co.nz/product/duo-uleb-by-tropicair/
https://www.ferva.co.nz/

Here's the authorized stove list in NZ
https://www.ecan.govt.nz/data/authorised-burners/

These look really cool.
Anything you’re reading that suggests these stoves may come to the US?

 

[begreen]

No, I was just reading up and looking at their testing results. NZ tests and rates for emissions and efficiency. It's interesting to see how some of their stoves and stoves available in our market compare in their testing.

The Wittus Twin-Fire is available in the US, but it is pricey. That said it burns super cleanly and it really blasts out the heat in front of the stove. It's the strongest I have felt.

 

[jetsam]

What's going on in that twin-fire? In the photos it looks like primary combustion is in the top firebox, and the bottom firebox is secondary combustion and zero wood?

 

[begreen]

Correct. It's a gasifier design.

 

[jetsam]

Correct. It's a gasifier design.

Yeah, the burner being under the firebox is odd. The #1 problem with gasification is usually stopping the gas from tarring up whatever lines and filters it passes through- any idea what maintenance is like?

 

[begreen]

I have seen it operated, but have not run one myself. It is a pretty simple setup with a special circular grate between the levels. You get the fire going strongly in the upper chamber, then shift the bypass damper into Twinfire mode. That sucks the flame through the very hot coal bed into the bottom chamber. This is very hot combustion. These stoves are not low and slow burners. They run more intensely on smaller charges of fuel. With proper operation there seems like little opportunity for tar buildup, but that may be possible if the wood is not fully seasoned, air control not set right, etc..