So, the ceiling joists are in opposition to the direction the duct work needs to travel?

Have you opened the ceing to check which way the support beams run?

I'd start with that then decide. It's cheapest to hide it in an existing structure rather than build something new and much easier to fix the ceiling than drywall essentially what would be a tunnel on the ceiiling.

Also the ceiling will look 1000 x's better if it doesn't have false beams.

Unfortunately the ceiling joists are in the right direction BUT the support beam from the addition is running the opposite way. There is no way to go above the support beam therefore we need to apply the duct work along the ceiling.

May be easy and more asthetically pleasing to see if you can reconfigure your existing cabinetry and move your cooktop along the perimeter. Is any of your kitchen along an outside wall?

This is what we are doing with our range hood duct. Using two 45 degree elbows allows the duct to go between the two vanity sinks in the master bath. Four inches of the duct's 10'' will be in the wall. The remaining 6'' will be in a chase that is trimmed out to blend with the vanity. My architect suggested doing this.

The red lines was the route that I had picked but that route involved a 7x13 oval duct and two transitions at each end of the oval duct. It also meant a single vanity due to the sloped cieling and the duct chase reduced the vanity width.

Modern-Aire can make a hood with the vent hole offset to the right so the duct can go straight up, doing away with the two elbows. I am weighing the cost benifit of this option.

While my wall hood has different requirements that your island hood, some of the ideas may work for you

Bill

Can you vent out the side of the house? My gf did that in her kitchen. Though the tub above the cooktop needed replumbing to make it happen, they were able to run it out the back between the floor joists.

As an alternative to round venting, you can transition to a rectangular material.However, you'll need the services of an HVAC duct designer to maintain the required volumetric efficiency of the venting appliance.
You can also mitigate the effect of the lowered ceiling height by addressing the whole ceiling, as an arch. element, as opposed to a small section that you become increasingly disapointed with.

Back again...for point of clarification. The ventwork will be vented out the side of the house, there is a 6 inch space from top of cabinet( on outside wall) to ceiling. The ductwork will run from the side of the house , over the cabinet to where the hood will be. (about 6 feet from wall to center of stove). So we are talking about hiding the ductwork from the wall to the hood. I am told the ductwork should be 3 inches high by 10/12 inches wide. Any suggestions to hide the ductwork.??? I am thinking of boxing it in and painting it white to match the ceiling. This, to me, would be less viusally offensive than a false beam.

Are you talking about a 90 degree turn in the vent duct?

"I am told the ductwork should be 3 inches high by 10/12 inches wide."

If by anyone besides the venting appliance MFG. or an HVAC designer, it's suspect.
3 x10-1/2 is a standard ducting available from any hdw. store.
But then again, will the person recommending it also be replacing the appliance motor and repairing the ceiling, at their expense, if their "guess" is wrong?

Thanks....Snoonyb, with a 30 inch dual fuel Thermador and a 36 inch Farber or XO hood spanning a length of about 6 feet, what size venting/ductwork do you suggest? The only person to come to the house, so far, has been the electrician.

As I have said in previous posts, ask the cooking appliance mfg. their recomendation for the min. size of the venting appliance.Then ask the venting appliance mfg., pose your delema to them and they may have answers for you.
Also ask them for technical specs for the appliance.
If they cannot, or will not because of liability, solve this, then consult with an HVAC professional for the duct sizing.
This is fairly simple math.
Also, if the proposed "boxing" of the duct work is to be accomplished with wood and drywall, you need to find someone familiar with steel framing.

ramica, you do have to go to the manufacturer for information.

Since you've posted "36 inch Farber or XO hood " but not the CFM, you are showing your ignorance. As a start, you must know what CFM means and then get the number of CFM for this hood. That is just the beginning of a number of steps.

Snoonyb and Davidrol,
I fully intend to follow the manufacturers suggestions, guidelines and instructions regarding the installation of the exhaust hood. Due diligence is being done by researching and asking questions so as to have better knowledge and understanding of the situation. A CFM is cubic feet per minute....to my understanding the ductwork needs to be of sufficient size to exhaust the amount of heat/gas being expelled by the stove . Each burner (4) has 18000 BTU and the manufacturer is recommending a minimum 600CFM blower, 36 to 42 inches wide for an island installation.
Hopefully by this post, I am not showing my ignorance. In addition, my original query was in regard to hiding or camouflaging the ductwork as it will be exposed and not in regard to the size of the ductwork. Thanks for your input.

Sorry to be dense here, but I don't understand why you can't run the vent between the joists...or do they run the wrong way....or do you have a concrete ceiling?

Ramica,

I'm having trouble picturing the obstacles you need to work around. Is the construction far enough along that you can post a photo of the ceiling in that room?

Laura

a false beam is a good disguise. We cannot say if it matches the rest of the house.

If the galvanized steel ductwork has to be tacked on to the ceiling, then any dropped ceiling, or dropped section, or soffit-looking thingie, or beam-looking disguise, is a good way to cover it. You can paint it too. You can wrap it with anything and call it done. It's definitely a problem to work around.

In your second post, ramica, you mentioned a 2 inch gap. I think this is a better problem to work around. I think this is worth a lot more attention. My hunch is that a good answer is somewhere here.

If the ceiling is not a concrete slab, it is made of joists, and is almost entirely hollow between the joists. The direction the joists go is the same direction that your ugly metal duct can go, too, for the first few feet. It might not matter at all if that direction is perpendicular to the direction you want. When the duct nears a wall, a transitional piece of ductwork can turn the air stream 90 degrees. This transition piece matches up to a run of standard size duct work that travels along the wall-ceiling junction (which can be covered by a soffit) over to the exterior wall hole where the duct is to go outside.

http://en.wikipedia.org/wiki/Soffit ....formed as a ceiling .... fix underneath .... underside of any construction element

"boxing it in and painting it white" is a soffit.

In a kitchen a soffit can become the place for pot lights directly overhead of the workspace (countertop). So, this is worth considering.

A 3.5" by 10.5" rectangular duct is the right size for a flow of air much smaller than your 600 CFM flow. A 3.5" by 10.5" rectangular size of duct is good for rental apartments with electric coil stoves and cheap exhaust hoods. ( ... "I am told the ductwork should be 3 inches high by 10/12 inches wide." ...)

A 600CFM stream will need a larger duct. The right duct size is specified by the manufacturer. It will be in their product's PDF on their web site. What size round duct is it? I'd say 8" is my guess. It could be another size. Transitioning to an appropriately sized rectangular duct is easy once you go get the right information.

Snoonyb posted in the first reply you got in this thread, asking about joists. Your answer was the wrong one. The next post from someone was from loves2cook4six who asked the same question that snoonyb asked, although the question was worded SO differently that it might appear to be unrecognizable.

Then you mentioned a new beam, going the other way from the joist direction.

I believe there is a way to go through the support beam "from the addition" even though it is running the wrong way. In the remodeling forum you will get experts telling you how to reinforce a beam in such manner as to allow you to cut a hole through it.

I believe there is a way to send the duct through the empty space above the new beam and between the joists. This may be the optimal path of study for you today. Remember that the new beam is perpendicular to the set of joists in the ceiling, and it does not fill the empty space that is still there and just as much available as it was before the new beam arrived.

Hth

How high is your ceiling?

I guess the bottom line of the posts here is that while you can disguise duct work, it is so much better not to have the issue in the first place so it is worthwhile exploring all other possibilities thoroughly before embarking on the disguise option.

I hope Ramica hasn't disappeared because of davidrol's comment about ignorance....

I don't know anything about the design of your kitchen, so this thought may not be useful, but: have you thought that you can leave the duct exposed, and not disguise it?
Lynn

Hello, I have not disappeared...the hide is thick. As I stated previously, this is not a renovation or remodel( that was done 22 years ago and it still is modern and up to date). It is just an attempt to replace an existing island dual fuel downdraft range with a new one. Then the problems/issues started. All reviews and information were mostly negative regarding downdrafts and/or Jenn Air ranges.I then decided to research a different range and the possibility of installing an overhead exhaust hood.But just because it seems doable/simple, it is not. I think that my best course of action is to hire a HVAC technician to evaluate the kitchen area. Thanks to all to have contributed to this forum.