Large L-8 Firebox


All JUCAs are known for their large fireboxes. Where competing fireplace inserts generally have 2 to 3 cubic foot fireboxes (to make sure their one-size-fits-all unit fits all fireplaces), a JUCA L-8 is CUSTOM-BUILT to the Mueasurements of the specific fireplace! This allows the largest possible firebox size ... WAY larger than any competitive one-size-fits-all Insert could have.

Of course, this allows you to burn much bigger pieces of wood, and to load more of it at a time. So convenience is a result.

The large firebox also allows more total area of heat exchanger surfaces. This means that more heat can be captured and transferred into the pure room air.

Another result of the JUCA's larger firebox is that thicker logs can be burned. It turns out that wood (or anything else) can only burn (or oxidize) at its surface, where it can interact with the oxygen in the air. As that surface wood burns and disappears (or falls away), new wood is exposed which can then burn.

Thick pieces of wood therefore burn gradually (and evenly) for a longer time. With this fact in mind, a combustion system can be designed (as in the JUCAs) where plenty of oxygen is available around the fire area. As each particle of wood burns, there is plenty of oxygen present to ensure extremely complete combustion. Therefore, very high combustion efficiency exists and very little pollution or creosote is created in the smoke. At the same time, the thickness of the wood pieces causes rather constant heat production for a very long time. All the desired characteristics of a perfect wood-burner!

Most competing products have smallish fireboxes. This then requires small, split pieces of wood to be burned. These small pieces of wood would burn up very quickly in the presence of a lot of air, as they did in the old Potbelly stoves and Franklin stoves. Those units burned reasonably cleanly, but created heat for only an hour or so, and too much during that hour. Therefore, many manufacturers turned to limiting the amount of air available to the fire, the so-called Air-Tight design concept. That DID accomplish their goal of longer burn time and more even heat production, but at the cost of incomplete burning due to insufficient oxygen present for all the chemical reactions which need to occur in complete burning. Therefore, they are forced to try to complete these reactions later, either in a catalytic combustor or by adding heated secondary combustion air later (or both). Life is very complicated for designers of such devices, because the basic premise of Air-Tight operation has such a major flaw. In real life, the great variations in wood type, its dryness, wood piece thickness and quantity, all greatly affect the effectiveness of these attempts to cure the Air-Tight product's problem of poor burning. Sometimes, the cure works just like the designers intended. Sometimes, it is totally ineffective.

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JUCAs NON-Air-Tight design allows such complete combustion in the original flame tips, that normal operation is better than that even when Air-Tight products are operated at their optimum.






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E-mail to: JUCA1@mb-soft.com