INFORMATION, DUCTING If you intend to join an existing duct system, there may be two ways to go: IF THE WARM AIR DUCTS ARE METAL, then it MIGHT be possible to feed directly into the warm air ducts. Then the JUCA system would be totally independent of the other heating system. There are some things to watch for during installation. Join the duct system at its thickest point. Make sure JUCA heat ONLY goes toward the rooms and not backwards back into the furnace. Make sure that if the power goes out and the JUCA air gets much hotter, that the metal of the ducts would not cause nearby wood to catch fire. IF THE COLD AIR RETURNS ARE METAL ONLY (NOT METAL PANNED JOISTS, ETC.), then it MIGHT be possible to feed into the other furnace's cold air return. In this case, the JUCA blower will only have to move it's air TO the cold air return, where the other furnace's blower picks it up and distributes it from there (without that furnace's burner being on). There are even more safety considerations to consider when using this approach. As above, it is critically important that hot air cannot go the wrong way in ducts and that, during power outages, that no nearby wood could catch fire due to the air in the ducts being much hotter. IF THE DUCTS ARE NOT ALL METAL, THEN IT MAY NOT BE SAFE TO USE THEM. CONSULT YOUR LOCAL BUILDING INSPECTOR. Sometimes there is STILL a way to combine the efforts of the JUCA and the conventional furnace blower. If that furnace has a major COLD AIR RETURN that is near the JUCA, then the JUCA could JUST send its heat into the rooms adjacent to itself, and the conventional furnace's BLOWER could be turned on to draw that warmed air from that room, and without further heating it, distribute that heat throughout the whole house. A manual way to do this is to just go to that furnace's wall thermostat and move the sub-base's FAN switch to its ON or SUMMER FAN position from its normal AUTO position. There is also a simple way to automate this, to close this switch whenever the JUCA blower turns on, while still allowing it to work normally whenever the other furnace's burner needs to turn it on.

Whichever way you intend to hook up the ducting, make sure to have a heating contractor do the work. He will know all the safe procedures necessary to keep you and your family safe. Also, make sure that you take into account that the first 10 feet of hot air ducting MUST be insulated from any wood.

Reasonable air flow and heat delivery requires certain planning that must be done for your particular application. Each house is unique and so is its ducting system. That's another reason for having a local heating contractor do this work. Even if we would try to give guidance over the phone, it would ONLY be general, and might not apply because of unique aspects of YOUR house.

Elbows and angle fittings in both directions are standard available items for the size ducting that JUCAs feed.

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FEEDING INTO WARM AIR DUCTS:

This connection method involves considering installing air filters and a humidifier in the JUCA air path, because its air does NOT go through those features of the other furnace. JUCAs are compatible with ALL standard air filters and humidifiers.

Another way sometimes used

This "alternate" type of connection is a little more complicated than it first seems even though it is a way recommended by some of our competitors (we think, incorrectly). The ONLY appropriate ways to do this involve EITHER getting the JUCA blower that is about the same size and capacity as the blower in the other furnace (so it can't be over-powered) OR to design the connecting point to have a "venturi effect" as mentioned above. If this is done correctly, the air flow of the other (big) blower, is capable of causing a "sucking" action to actually help pull the JUCA's warm air out into its path.

If you do use this method, you should check the JUCA's hood temperature when operating. If it is hotter than allowing you to hold your hand against it, then probably the air is not being able to leave the stove properly and some change in the connection area is necessary.

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FEEDING INTO A COLD AIR RETURN:

When the JUCA is operating, the air in the cold air return duct is drawn into the JUCA, heated up there, and then put back into that same cold air return duct (after the BAFFLE shown). Then the JUCA-warmed air proceeds to and through the other furnace's blower, on its way to the house ducts. ONLY the blower of the conventional furnace operates (NOT the burner, so no fuel is used). That (large) blower does most of the work of distributing the JUCA-warmed air throughout the house.

This configuration still requires at least the standard blower to operate on the JUCA. The other furnace's blower is not designed to "suck" the air through the JUCA, as that would cause something bad called "cavitation."

When the JUCA is NOT operating, the conventional furnace pulls MOST of its air by its original path, past the BAFFLE, and pulls the remainder through the JUCA heat exchanger path. The conventional furnace operates normally.

It would also be possible to make the BAFFLE motorized. Then, the cold air return duct would remain totally unobstructed for the normal operation of the conventional furnace, and the BAFFLE would swing out and divert most of the air through the JUCA air path when the JUCA blower turns on. The motor of that damper would just be wired in parallel with the JUCA blower, so it would turn on and close at the correct times.

This general arrangement's air path ALWAYS passes through the conventional furnace's air filter system and humidifier.

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A SEPARATE DUCT SYSTEM

Sometimes, in houses that currently don't have ducts, people operate the JUCA for one winter, to see how much of the house can be heated to the comfort level desired, without ducting. If the results are satisfactory, then nothing else would ever need to be done. But, if it was found that a single distant bedroom or bathroom was not warm enough, it would be possible to run one small duct the following year, to get some extra heat to that area. JUCAs are amazingly flexible in such ways!

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AN UN-DUCTED DUCT SYSTEM!

It would even be possible to automate this kind of installation with a Relay as described below.

Notes

Relay

The following describes a "NON-invasive" method of connection that does NOT involve doing anything inside the other furnace. The SPST relay would be used. The coil of this relay would be wired in parallel with the JUCA's blower motor, so the relay would be actuated whenever the JUCA blower was on.

The SPST switch contacts would be wired in parallel with the 24-volt circuit SUMMER FAN switch in the sub-base of the conventional furnace's wall thermostat. The effect would be so that the SUMMER FAN circuit would be automatically closed, just as if you manually moved that switch on the sub-base. This method does NOT invade the other furnace, so it does not affect any warranties or anything!

Other Notes

MAKE ABSOLUTELY SURE THAT ALL OF THE FIRST 10 FEET OF WARM AIR DUCTING FROM THE JUCA IS INSULATED FROM ANY WOOD OR OTHER COMBUSTIBLES, EVEN IF IT MEANS MODIFYING EXISTING DUCTWORK.

If the JUCA is installed in an unheated space, then a cold air return MUST be provided for the JUCA. There are a LOT of good reasons for this. Trust us!

If ducts pass through an unheated basement or crawlspace, they should be insulated with Fiberglas insulation, to minimize heat loss in those ducts, just like with any other furnace.

It is extremely important to measure the "Static Pressure Levels" and air flow rates. Otherwise, any or all of several problems could occur.

• The existing furnace may wind up pushing a load level it is not adjusted for. (Either too high OR too low!) That could be hard on that blower's motor.
• The JUCA blower may wind up pushing against a duct pressure load outside of it's allowable range of operation (see the chart below.)
• The two blowers may wind up fighting each other.
• Some rooms may get a lot of warmed JUCA air while others get less.

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