Range hood, fan size..

[Chuck]

Going to have to install range hood with outside exhaust (through the roof) this weekend... I'm having new roof installed and want this in prior to new roof so I'm pushed for time.. My current hood is just a "blow steam and grease in the top of your head while cooking type...

My length of ducting is well below the max for either.. 7ft of 7" round duct with no turns. Possibly needing a rectangular to round adapter depending on model of hood It's a 30" hood.. I see some with 220 cfm and 390 cfm for twice the money.. Is the 390 cfm needed? $380. for the 390 cfm $130 for the 220 cfm I wouldn't mind the 390 cfm as much if it's strong enough to pull in fresh air if something get's "funky" smelling.. and I open a couple windows.. though I know it's not a whole house fan... Thanks.. Chuck (in SC)

[Joseph Meehan]

I did not see anything in there about noise. A fan that makes too much noise is not going to be used. I suggest you consider that in your choice. As for a hood fan clearing out a smoky room, I think you are expecting too much. Any good hood fan will keep the room from getting bad, but only if you are using it. The trick is to turn it on EVERY time you are using the range. I believe you would be better served by the lower cfm and using it every time than the larger one. Of course if you use the larger one all the time that would likely do even better.

Note not all hood are equally effective even if they have the same cfm.

[Frank Boettcher]

If you have a homecenter close by you can go and operate each of them and make a better decision. I recently installed a Broan quiet hood

20000 series which is just 200 cfm and find it to be plenty to keep odors and steam removed from the area. It is infinitely adjustable and I usually don't put it on the highest setting

The 7" round adapter comes with it. also the rectangular.

I never deep fry inside, so don't know about that. Do that on the patio.

Frank

[Mr_bill]

assuming that your exhaust ducting goes through the roof you want to replace, I would start *there* by putting an 8" dia roof jack in. This will allow you to install a range hood with up to 600 cfm, now or in the future.

You didn't mention whether your cooktop is gas or electric. For electric, your local building codes might allow as little as 200cfm, but I would go 300 cfm minimum.

If you have gas, or are contemplating gas in the near future, I would recommend (and some codes require) 600 cfm minimum.

Bill