I am installing a 30 inch Viking hood with an internal blower 300 cfm. The specs specify 7 inch duct up to 50 feet long. I am only going 6 feet horizontal with a gradual 90 degree elbow adding maybe 2 feet. The space is very tight and I am wondering if I can use 6 inch duct and not loose performance? Viking was no help.
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From my experience you are usually wise to follow the guidelines of the manufacturer.
However, you may only have a noise increase by dropping down one inch in diameter. The run is so short, certainly there won't be a problem pushing the air. If it's variable speed, you can probably lower the noise by putzing with the max speed you set.
Straight up is a bit quieter, quick turn adds some noise.
If this is your place, you decide. If a job, let the homowner make the decision.
A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time
It will probably still work , sometimes you gotta do what you gotta do . But if you can install as specified . 300 cfm seems....small , and in my expierence most of these hoods are more for decoration than actually working.
Try posting this Question over at the COOKS FORUM . They may be able to give you some info. on how well this fan actually works .
DAVE
I am going through much the same thing -- 300 cfm is for looks -- we have to go 1200 and it is a 10" from the out side reduced to a 8" -- we need all the room we can get and might end up squeexignhe 8" a tad -- ours is no the outside -- the big benefit of outside versus inside is the noise -- you are supposed to not hear a thing
You will have bought your hood for looks if you reduce the duct size from manufactors specs. I get these questions very often customers, Most of the time there are options ( usually more than they want to spend ) If you have need of a 1200 cfm hood you install it properly so it will move 1200 cfm.
wookie -- we are following the specs -- it is 10" though the wall and then it steps down to 8" -- can guarantee we are not cutting corners on this job --- we would need the full 10" if we were going for the 1500 cfm but with the 12 we can go with 8 inside -- tks for the tip though
I have spoken with the appliance dealer and they suggest going to an 880cfm with the the 6 inch duct will give me the same air movement with a increased noise level but they say you seldom operate the hood at top capacity and when you do you don't care about the noise i.e. smoke. Sound ok?
kbd. How much more is the 880 cfm?
If the 880 can use a 6'', could we not assume the 300 (same as many over-the-range micro exhausts) would do ok with a 6''?
I'm no technician or air movement engineer, but many times a viking or other semi commercial / now being used in the home hood salesperson stretches the truth or recommendations a bit. What is the range under this hood? Are you going to cook like the flaming chefs in a full service restaurant?
880cfm's is on the verge of needing makeup air so you don't suck the exhaust fumes out of your furnace or gas water heater.
Just some thoughts to further confuse the issue.
Best of luck.
A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time
It is a four burner 30" propane gas stove without a grill unit. Spacewise do to plumbing and joists, I have to go with the 6" duct when 7" is specified. The blower is on a rheostat type switch so I can adjust the speed of the fan. It will probably be on very low if at all most of the time.
All I can tell you is think of the price, the look, the application and the 6'' duct spec'd for the 880 cfm v. the 7'' for the 300 cfm (which except for the stepdown, seems to me like it would work in this application). Again, what is the cost of the two hoods?
Best of luck.A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
Quittin' Time