I just installed a Viking range hood with an inline motor attached to 10″ round duct. I found the pipe and the cap, but am having trouble locating a flashing to fit a 8/12 pitch asphalt shingle roof. Local sheet metal supplier only carries up to 8″. Does anyone know whereto find a 10″ flashing, or can I reduce pipe to 8″? Any replies would be greately appreciated.
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There would be absolutely no sense whatsoever in spending all that green to have a big old SS sucker in the kitchen and then choke it down by 35% flow rate. That would be like buying a powerful 4x4 and then driving around on three wheels.
You need a backflow preventor too. Sounds to me like you have the wrong terminus. With the right cap through roof, you make the duct angle in the attic and it approaches the roof plane at 90°
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With the right cap through roof, you make the duct angle in the attic and it approaches the roof plane at 90°
When I make roof jacks for these things (I've got a 10" dia in the works, now), I make the opening elongated to match the roof pitch so they can bring the pipe straight up into the jack. That also allows the height to be reduced slightly since the air is dispersed out of the pipe in a wider area.
View ImageView Image
How do you determine the cutout? Do you draw the ellipse or cut a 10" pipe at the roof pitch and trace?
Jon Blakemore RappahannockINC.com Fredericksburg, VA
>>>>>>>>>>>>>How do you determine the cutout? Do you draw the ellipse or cut a 10" pipe at the roof pitch and trace?I used to lay it out on paper first and cut a cardboard mock-up. Now I use Sketch Up and I'm using cardboard mock-ups less, although they're still pretty handy for some things.View Image
Check to see if there is an ABC supply around you...
BTW... 10" hu? What, is it like 750 CFM or something?
Edited 10/9/2008 6:59 am ET by Matt
900 or 1200
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1200 CUBIC FEET PER MINUTE!!!
Jeese... That would equal a full air change every 9 minutes in a 1200 sq ft house with 9' ceilings.... Every 18 minutes in a 2400 sq ft house....
Once built a house for a guy who was a little funny.... but a great customer :-)... big fancy gas range, big hood all that... when the house was done.. : "Oh no... I don't cook...." Wasn't kidding either.... Went back about 2 months after the move in... dishwasher leak. "Oh - I've only used it twice...." Who uses their dishwasher once a month???
The 900-1200 are the ones that totally REQUIRE the 10" duct, IIRC.Yes it is ridiculous, but folks buy them - even if they only cook twice a month, and one of those is the caterer!What as lot of folks don't realize is that they need a good supply of makeup air to be able to stay healthy. Tjhe salesman talks them into a super big Boeing exhaust hood thqt "only costs another $250", then they learn that installation is a thousand dollar upcharge over the 600CFM unit and faint dead away.
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Graingers would be able to supply her too.Ya know, if the fan is only a 750, then an 8" duct at top end might work for a fairly short run.
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Fantech makes all sorts of roof flashings for 10".
http://www.fantech.net/accessories4.htm
Also check out hvacquick.com, they appear to have a good selection of roof jacks and the like.
While we're on the subject of running big #### ducts for range hoods, how are people able to stuff a 10" duct into standard 3.5" wall cavity? ;)
I know that they make 3.25"x10" duct for low cfm hoods, and I guess you could go all the way up to 3.25" x 14", but thats only equivalent to a 7" round duct. I have to run the hood duct all the way to the roof through my second story, and I don't currently have a chase for it, nor planned for one.
Also, has anyone installed an exterior vent fan? I'm looking at the Fantech units, since I think it makes complete sense to move the source of the noise as far away as possible, but it does nearly double the cost...
Z
"how are people able to stuff a 10" duct into standard 3.5" wall cavity? ;)"three options there.One is to go straight thru the wall with a thimble. I had one set up ( I think from Therma-tru) that had an exterior cap that looked like a wheelbarrow mounted on the side of the house. I didn't even think of using it, but designed one with my SM guyAnother is to design so that the duct runs straight up through the roof, using ceiling soffit and cabs to hide the duct.On two of them I used the soffit to redirect. On one, I had a large closet behind the wall with wasted space, so I ran a chase to take the duct down and out under the floor. On another I was able to jog far enough over to hit exterior wall and turn out
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I wonder if my archys work was good for anything but the stamp. He was the one who specified the vent to the straight to the roof (no wall space for a 10" hole), but clearly didn't make any closets or soffits anywhere near the kitchen to run the damn pipe in. Thanks for the suggestions, definitely good ideas that I need to now figure out how to execute on.Z
Thanks to all of you who replied. I believe Fantech has just what I am looking for,a sufficient vent that is not too obnoxious looking from outside. I will have to run a bend in the attic area since it mounts perpindicular to the roof deck but that is not a problem though. By the way the motor is 900 cfm and the 10"pipe runs up the wall 1" away from the finish drywall and gets wrapped with a 3 sided stainless box which hides it from sight. The motor looks like it should be hanging off the wing of a boeing aircraft,yet it is relatively quiet. Thanks again for your input.