F-9A Warm Air Outlet Provision

JUCA built-in fireplaces are normally built ONLY with an 8" by 16" warm air outlet. This large warm air outlet can feed warm air to either or both of two destinations. One is into a house warm air duct system. The other is to one or more warm air registers for the room that the JUCA F-9A is in.

These two capabilities are relatively independent of each other. For installations in houses that don't have warm air ducts, it is possible to ONLY send warm air out registers near the JUCA. Other installations may need to ONLY to send it into a duct system. Or feed warm air to both!

Feeding into a house duct system

Brief description on feeding a duct system.

Feeding room warm air registers

For feeding registers in the room, BRANCH DUCTS are used. This is a normal arrangement in warm air house ducting. When you have been in basements, you probably noticed a large rectangular shiny duct along the ceiling. It usually has a bunch of smaller round branch ducts connected to it, to take the warm air to individual room registers upstairs. That's the concept involved regarding supplying warm air registers in the room that the JUCA is in.

This allows tremendous versatility in placing the warm air registers. They do NOT have to be on or next to the fireplace door opening. They could be in a different wall!

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We usually suggest having these register outlets mounted LOW in the wall. This allows the warm air to keep your feet warm and to spread warm air to a large area of the room (and often, even adjoining rooms) without needing to use the ducting capability of the JUCA unit. Often, if the JUCA has a raised hearth, the register outlets could be mounted in the "kick-panel" area just below the hearth-stone. There are even creative ways of letting this air come out this area through a lattice-work of bricks, so no visible metal register or grille is even there. In addition, brass or black decorative antique-looking grilles exist for this use.

Most competing fireplaces have their warm-air (actually hot-air) outlets high up on the product, and the hot air is directed upward. Well, duhhh! It doesn't do anyone much good up there! Warm air rises (remember High School Science?) and it goes right to the ceiling. As a matter of fact, the very high temperatures of the air coming out of such competing products encourages the air to rush to the ceiling even faster!

So why do they design their products with such strange logic? Well, it allows their products to seem like they produce more heat than otherwise would be possible. That configuration allows and encourages a process called "Thermo-siphoning" where the house air rises naturally while being heated in their units. This has the effect of making it seem like there IS a small blower on non-blowered products, and it makes it seem like their small blower is moving more air than it normally can.

Such units often produce VERY hot air coming out. A customer feels this hot air, and can sometimes be misled to believe that the high temperature is proof that the product is creating a lot of heat. Strangely enough, this is not the case. If a product has a sophisticated heat capture (called heat exchange) system (like a JUCA), and appropriate larger blower (to ensure appropriate Reynolds number and turbulence), it can actually have substantially better overall efficiency and performance by keeping the heat exchange surfaces COOLER inside the unit! (See other entries on heat exchange and our Technical Series for more on this.)

In any case, JUCAs are designed for absolute optimal performance, whether using the Ducting capability or Room Registers, or both!

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