Comparison To A Conventional Gas Furnace

Often, customers ask about how well a JUCA heats as compared to other brands of fireplaces. Well, that's not even a fair comparison since the JUCA vaporizes the competition. It is more appropriate, in performance terms, to compare a JUCA's performance with that of a conventional gas or oil furnace. After all, the sophisticated JUCA heat exchanger is basically a heavy duty conventional furnace heat exchanger!

Many house conventional furnaces for cold climates are rated at 100,000 Btu/hr or 125,000 Btu/hr. This is an INPUT rating of how much gas is consumed per hour. Since convent- ional gas furnaces are often rated at 80% efficiency, this produces an OUTPUT capability of 80,000 or 100,000 Btu/hr.

When gas furnaces are designed and matched to a particular house, the heating engineers intend that the BURNER ONLY BE IGNITED TWO-THIRDS OF THE TIME at the design winter temperature. This approach allows for some extra capacity for days BELOW the design temperature. For example, the design temperature for the Chicago area is -10°F, but a few years ago it actually got down to a record -27°F. Gas furnace burners in Chicago were on MORE THAN two-thirds of the time on THAT day!

Since the burner cycles on and off in a gas furnace to achieve the two-thirds proportion, it is designed to be producing heat two hours out of every three which is the equivalent of producing continuous heat (like a JUCA does) of two-thirds as much. Therefore, the average furnaces mentioned earlier are ACTUALLY comparable to a continuous heat OUTPUT source of 53,000 or 67,000 Btu/hr.

This actually makes good sense. A thermal heat loss analysis for an average-sized residence in a cold climate (like Chicago) usually indicates a design heat loss of about 40,000 to 50,000 Btu/hr (at the design temperature, of course!).

Text Font Face
.
Text Size
.
Background
Color
.
(for printing)
The point is, you probably ACTUALLY need 50,000 Btu/hr continuous OUTPUT to entirely heat your house, not the 125,000 Btu/hr of the furnace rating plate. Isn't that an interesting new fact to learn?

Since our woodburners are only rated by OUTPUT, even our little K-3 or B-3J can produce enough heat to heat most average-sized houses. So, why shouldn't you get one of these littler (less expensive) models? For a DIFFERENT very good reason! The size of the firebox is the secret! The K-3 has a 3.0 cubic foot firebox, about the size of the bigger competing woodstoves. The B-3J has 5.5 cubic feet, and the B-3B has 9.5 a cubic foot firebox! HUGE!

There are TWO major benefits from having a bigger firebox. In a B-3B, you can load pretty much any piece of wood you can carry, so there is far less splitting necessary. But, more importantly, the giant firebox allows you to put enough wood into it to be able to produce enough heat for the entire house for 8 or 10 hours. If you're going to need to burn up 10 pounds per hour to produce 60,000 Btu/hr, then you're going to need to have at least 100 pounds of wood in the firebox, if you want it to supply that much heat for 10 hours!

The B-3B and B-3D series have giant fireboxes and high capabilities and over 20+ years we have found ALL owners thrilled with the output. That's why we began offering the PERFORMANCE GUARANTEE in 1989 which assures a buyer that THEIR house WILL be totally heated with their JUCA.

Another area of contention in woodburning is variation in heat output. Most people are aware of the pot-belly characteristics of roaring heat for one hour that drives you away, then an hour of shivering. Not so with a JUCA.

JUCAs are larger and have larger fireboxes than any of our competitors. There's an important reason for this. A large firebox allows use of THICK pieces of wood. Thick pieces of wood ONLY burn at their surfaces which is where the oxygen is present for the chemical reaction of burning. Only after the outer surface burns away, can the next layer burn. Thick logs burn for a long time!

Think about when you have camped overnight. In the morning, the campfire is long burned out, EXCEPT for the thick logs which are still slowly burning with a constant (but small) amount of heat production. JUCAs use this aspect of nature. Thick logs burn long and evenly (and very cleanly) but with moderate output.

JUCAs use a sophisticated, computer designed heat exchanger above the fire to capture this heat efficiently to heat the house. Very even heating and very long burn times are achieved. Owners often comment that the comfort level in their house is even better than when they heated with gas or oil. That's primarily because of the constant heat gener- ation rather than the cycling on and off of the gas burner.

JUCAs match up remarkably well with gas or oil furnaces, in heat output and in occupant comfort level, Inconvenience of wood is minimized by only having to load a JUCA at 8-hour intervals under most conditions.


The JUCA Home Page is at: juca