We are installing a 48" Wolfe ventilator with an 1200 CFM external fan, and I wonder if it is smart to install a noise reduction device/muffler between the hood and fan?
This post was edited by alltrade on Sun, Jul 20, 14 at 9:26
Because I have installed the bigger brother to that configuration, it might be too conceited to agree on "smart," but I would assert "useful," .
An in-line muffler will remove most of the fan blade tip noise, and duct turbulence noise from the ducts on the roof side of the muffler. It will not remove local to the hood turbulence noise, including that from the baffles. It will not remove much motor rumble, as that is too low a frequency for the size (already very large) of the muffler.
Some duct vibration will escape removal, but can be greatly attenuated using sound dampening materials. I use a heavy vinyl product used for automotive door quieting, with its adhesive power enhanced by being strapped onto my 10-inch ducts with long tywraps.
I can carry on a normal conversation while standing at my hood with the "1500-cfm" roof-mounted blower on full power.
You may find it useful to review some of the vast number of hood related threads on this forum, as well as the references in the material in My Clippings.
Thank you. Your advice is duly noted and we will install a muffler. Final plans for ventilation, for a 48" range with griddle and grill, will be a 54" hood with 1500 fan.
We have an open plan house, so good ventilation is important.
Final question; How high above the stove top can I mount the hood?
My hood is at 34 inches above a side-by-side induction cooktop and induction wok configuration. I think you should draw a stick figure side view of the cook, the countertop, and the hood and check sight lines and waist bending arc to ensure no head intercepts.
Halogen flood lights used in Wolf's hood (or at least mine) are quite hot above one's head, so if your standing position is non-fortuitous w.r.t. the lamp layout, consider changing to LED floods.
The technical answer on hood height would be based on the effluent expansion angle that varies with pan temperature and grease and water emission rate, along with pan size, accounting for some slight draw-in at the aperture edges.
I find wok cooking on one side of my hood to be collected acceptably with an 11-degree half angle (outermost hot part of wok to interior edge of hood aperture), but the Finnish papers at My Clippings show up to 22 degrees half angle expansion occurs for some cooking (generally commercial in their case). I don't grill on my cooktop.
1500 cfm nominal for your hood size, which is modestly smaller than my pro-island hood, should provide good containment, and some enhancement of capture area due to air flow. Most of the time you will find you can run at lower blower settings and capture most generated effluent from normal cooking. However, for grilling you would be advised to have the grilling zone in the center of the cooktop, and ensure adequate make-up air so that the actual cfm is only limited by the baffle loss, hood transition loss, silencer loss, and duct losses. You want to use 10-inch duct for this flow rate.
Install the hood so that it is centered over the cooktop and not over the counter that the cooktop is in. (This only applies in one direction if you are mounting on a wall.) We want to strive for maximum effluent capture and not room symmetry. If you want room symmetry, change the location of the cooktop to be under the hood.
Joists above the cooktop may need to be revised to accommodate the duct and the mounting locations of the heavy-duty screws needed to hold these monster hoods. I have an 8-foot ceiling where the hood is mounted, and an extension (from Wolf) is used to establish the hood height.
Island hood mounting is most easily done if the counter is not yet in place and a drywall lift is used. Or a team of competitive weight lifters might be employed. Wall hoods may be mountable using props or temporary structures; I have no experience with them.