I am not quite following the problem but this may help...my insert ended up not fitting properly in my limestone hood due to a problem with the stone company and their drawings. I took my insert to a local sheet metal fabricator and for $300, they cut down and rebuilt the insert so it would work for my hood. Maybe you can do the same??

I agree with cleo07. You may need to have the ducting by your liner custom fabbed. Your HVAC guy could not make this work?

It's not a ducting problem; it's a space problem. I need 18" before the first duct turn - I have 10".

Will keep the sheet metal fabricator as a last resort. Good idea. Thanks

Could you use something like a Fantech hood liner that is essentially a box with the filters in it, and attach an external fan or inline fan somewhere along the run?

I am using one that is 4" tall. Of course it's an empty box and the fan has to be remote. Mine will be an inline fan along the run. Another option is exterior wall mounted or roof mounted.

@Mishmosh, I guess I don't really understand the issue then. Can you please explain? I was told that we needed a total of 30" - 12" for the height of the unit and 18" for the duct before it makes its first turn. We have 22". How does a custom joiner help here?

@palimpsest Ooh! Thanks! How do you like it? Is it quiet(ish)?

I don't have the kitchen one yet but the bath versions are very quiet

Shari-- I don't entirely understand your layout/space issue either, but if you can swing a blower that's farther away from the kitchen I'd definitely suggest you give that a strong look. We bought and installed a 42" Zephyr Monsoon vented strait up into the attic and and then at a slight angle to and out the roof, but we found it so aggravatingly loud even on the lowest setting that we replaced it with a Wolf liner, inline silencer and Abbaka roof mounted blower. During this process I downloaded a decibel app to my phone, and the Abbaka setup (1400 cfm) is quieter on high than the Zephyr was on low. Despite the bitter pill of having to buy two ventilation systems, we're very happy we switched.

Wolf literature shows the liner is 12" tall, and I'm not understanding why you can't attach an elbow to the top of that that turns where you need it to at 22". Wolf isn't the only maker of liners, so you can shop around--I like the fact that it has a variable speed control rather than pre-sets like the Zephyr, but I've discovered it doesn't have a grease collection reservoir which seems like a strange omission.

If I understand your situation correctly, you need to mate a horizontal duct to the opening of the hood insert but don't have room for a 10" elbow. That can be accomplished by a custom box that sits on top of the insert and has a 10" opening at the back. An HVAC guy works custom fabs boxes all the time for ducting.

I was also thinking that maybe a rear vented hood insert might work for you. Maybe you could draw what you need but in the end, I would think that the contractor can make it work.