Island range hood installation


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Old 02-07-11, 05:06 PM
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Island range hood installation

Hopefully a quickie here:

I'm installing a new hood over the range in my island. Is it going to be the end of the world if I can't install it perfectly centered over the range? If it were 2 or 3 inches back from the front of the range, would that be OK? Or does it have to be perfectly centered?

And, if it must be perfectly centered: I would be able to install one side of the support bracket on a pre-existing joist. I have run two 4x4s on top of the existing joists, perpendicular to them. If I were to take a 2x4 (perhaps 2.5' long) and affix it to the bottom of the 4x4s with joist hangers, would that be structurally sound enough to support ~115lbs? That seems like a lot of weight hanging from 4 joist hangers...

Thanks so much for your help!
-S
 
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Old 02-17-11, 12:11 PM
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re: Island hood installation

As long as the inspector (at least in Ca.) isn't coming to see it, 2 or 3 inches from the front won't effect the performance of your hood. Hoods very rarely are the exact same size of the stove top. As long as the width is the same and the burners are all under the hood, and you have the proper cfm, you should have no problem at all
 
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Old 03-14-11, 08:53 AM
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Hey, thanks, Exhaustedkitty, for responding. Sorry for not acknowledging earlier - I gave up checking the thread after a few days.

I have another, hopefully quick, question. I >finally< got the darn thing installed. (If I never have to do ceiling drywall repair and work with metal ducting again, it'll be just about right.)

Once installed, though, I was surprised by how noisy it is. I was expecting, because it is an external blower, that the unit would be quite quiet. So I'm curious if it is just a configuration thing or if I may have done something wrong. Here's the configuration:

Island hood -> 2ft length of 8" rigid, round ducting -> 8" elbow at ~45 degrees -> 8" to 10" reducer -> 10" elbow at ~45 degrees -> 18" length of 10" rigid, round ducting.

So, there is about 5' from the hood to the blower. Is there something inherently wrong in the configuration I've got in there that would cause what seems like a lot of rattling? FWIW, all the joints (that I can access - the connection of the 8" duct to the hood itself is inaccessible) seem solid. I affixed them with 2 screws each, covered the joints w/ DP1030 and aluminum tape.

Or could it be that when you have a 1000 cfm blower 5' feet from the hood, you're bound to have a bit of noise? Is there a way to abate it at all?

I know it's tough to give input w/o being able to see the actual install, but any ideas or thoughts you can offer would be really appreciated.

Thanks, folks!
 
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Old 03-15-11, 01:04 AM
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Or could it be that when you have a 1000 cfm blower 5' feet from the hood, you're bound to have a bit of noise? Is there a way to abate it at all?
1,000 CFM is a HUGE amount of airflow for a residential hood. Yes, it will be horrendously noisy, especially through that small of ductwork.
 
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Old 03-18-11, 11:58 AM
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Originally Posted by Furd View Post
1,000 CFM is a HUGE amount of airflow for a residential hood. Yes, it will be horrendously noisy, especially through that small of ductwork.
Really?! And here I was concerned it would be barely adequate. Most everything I read while preparing to buy said that I wanted a 1 cfm/ 100 BTUs (gas cooker) and then some additional amount of airflow because it was an island installation in a generally open-floorplan 25'x35' room.

Good to know that it'll just be a noisy beast. I think I'm going to try wrapping some insulation around the ductwork to see if that'll help even a little bit with noise. If nothing else, maybe it'll help to keep cooking heat from getting into the attic, and attic heat from getting into the house.

Thanks!
 
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Old 03-18-11, 12:45 PM
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Just an FYI, if you have any vented combustion heaters that are subject to back drafting under that negative pressure be sure to have the house tested to be sure you are OK. In general, 1,000 cfm is a problem and there should be some mention (in fine print) in the owners manual. Even if there is no warning, best to test.

Bud
 
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Old 03-18-11, 02:11 PM
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Translation: "don't run the gas clothes dryer while running the hood"? Cuz the hood'll just suck the ... what would it be? CO?... right back into the house.

I actually think I'm going to have a pro come out regardless and look at what I did. With both you guys mentioning how much oomph this thing should be providing, I'm thinking I did something wrong since it seems kind of sissy when I turn it on.

Looks purty, though.
 
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Old 03-18-11, 05:39 PM
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Yea he would have to have fresh air coming in for 1000 cfm
 
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Old 03-18-11, 08:30 PM
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My range hood is an inexpensive "builder's model" and maybe flows 250 cubic feet at best. My home was built in 1987 and is therefore rather leaky as concerns air sealing but I still open a kitchen window slightly when I run the hood. Even with all this I get quite a breeze through the one-inch window opening when the fan is running.
 
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Old 03-28-11, 08:57 AM
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Thanks, all, for the input!

So, it turns out that - like the big dummy I am - I had left part of the shipping bracket on the blower itself. (In my defense, it was metal, screwed on and looked permanenty. What's a girl to do?!) Because it wasn't screwed on very tight, it was clattering when the blower was on, causing a metal-on-metal noise. Doh!

So, up into the attic I went, deconstructed the ducts enough to get the bracket off, and now everything sounds, well... normal. It IS loud, but at least it is just airflow loud now. And it seems to be sucking just fine: I cooked a big, fatty duck breast last night, and the house didn't smell at all like grease, so... s'all bueno!

Thank you again. Your insight and input is very much appreciated!
 
 

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