Viking hood blower kits: In-line vs. External vs. Internal
I recently purchased a 42" x 30" Viking island baffle-style hood (VIH4208). This hood will eventually be over a 36" BlueStar Drop-in Cooktop (total of ~70K BTU), mounted 32" above the countertop. I was aiming for a 1200 cfm blower, but the three blower options for this hood have me baffled (pun intended). Should I use an internal, in-line, or external blower? My goal is to have the quietest system, realizing the exit to the duct will be near my deck.
This is an install on a first floor kitchen in a two story. The exit point would be on a small roof overhanging my deck's sliding doors.
The first picture is of the interior ceiling. the joists are 12 inches, 16 center-to-center", so I have about a 11 1/2" x 14" space to work with, so I am assuming that I can use a 10" round duct, as there are no obstructions from the light to the exterior wall.
The second picture is of the roof that, if the line is straight, will exit on the roof.
The third picture is the available area on the soffit.
Some options I've been debating:
Option 1: 1200 cfm internal blower. Blower has about 8 feet of duct with one 90 degree elbow above the hood.
I am assuming this would be the quietest option for the deck outside, but likely the noisiest in the kitchen? How noisy are the internal blowers for Viking hoods?
Option 2: Install 1200 cfm in-line blower just under the roofline. The in-line won't fit in the joist area, as it's over 12" wide.
If it doesn't fit in the roof area for a straight exit (or with a 45 degree down, exiting the soffit area), I would have to put another 90 degree elbow in the duct and run it under the small roof and exit it out the fascia. This would be adding another 90 degree and 8 feet to the length, which didn't seem like a good idea to me. How noisy are the in-line blowers? The Viking website mentioned that adding a VSIL10 duct silencer could cut the noise up to 50%, but I couldn't find specs for it to see if it would fit in the joist area. I don't know if a silencer would be effective that close to the hood...is it made for attic type installs?
Overall, would option 2 be more quiet than option 1?
Option 3: Use an external blower. I'm assuming that external blowers are really noisy outside and wouldn't be preferred to have it almost right above the deck eating area? Has anyone installed an external blower close to a deck like this? Would this also need a duct silencer?
Any experiences/suggestions would be greatly appreciated!