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Can a lower gauge duct make a range hood louder?

2 months ago
last modified: 2 months ago

(Update) Solved

Just in case any one finds this, the problem was the electrician wired the outlet wrong and the hood was getting 240V instead of 120V. Nothing to do with the ducting.

My range hood got 30db louder since moving it.

Have a Broan BWP1 30" ducted range hood. Advertised noise volume on mid setting is 3 sones (43db).

Installed it and ran for 3 months and it achieved about that sound rating.

Redid the kitchen, so took it down, installed it again, and now it runs at around 75db at the mid setting.

Tested the hood before mounting and it ran at the appropriate noise level.

Both installs have the same arrangement: one 6" 90 degree elbow and a 10" long run of 30 gauge duct to vent to outside

The biggest difference between installs is the new install uses a 24 gauge 90 degree elbow and the old install used a 30 gauge 90 degree elbow.

Could this be leading to the increase in volume?

The other difference is the new install is raised 6" from stove top when the original install was only 18" from the stove top. (ed. actually raised 8" to manufactured specified minimum of 26" from stove top - thank you commenters)

Is there anything else about my setup that could cause such a dramatic increase in noise level?

Attached is a picture of the original install

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