I’m putting in a new range hood to replace an old Jenn-Air downdraft setup. My choices are to run an 18-ft horizontal duct to a gable, or go straight up 6 feet through the roof. I’m leaning toward using a roof vent cap. The low-profile ones with the built-in damper flap look like the wind will just rattle the flapper night and day. Are there better options for the roof cap? The blower is 600 CFM.
Thanks in advance
There are some instances where multiple minisplits make sense.
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Replies
I have been interested in this subject myself over several years. My parents' house have 3 rectangular vent covers that are made of thick gauge copper and the flaps still open and close well. So I have been looking for something like them all these years. No luck. I looked at several mail-in tool catalogues and hvac store catalogues and displays as well. They all are of quality that you can find in Homedepot.
For my house, I used roof vents for bathrooms. One year, there were few hard pouring rains. The rain deflected off the roof and into the vent, severely damaging the bathroom ceiling. The HD vents also have small plates so that less of the roofing covers the plate. Next time I renovate, I would put the vent in the wall, not on the roof. My roof has 4-1/2x12 pitch.
For roof vents, first, when you are buying them, look at them carefully for construction, for example, does the cover sit flush against the opening? Second, I made the roof of these vents larger with aluminum sheetmetal and bent the sides down so deflected rain can not get into the opening. Third, I made the flashing-plate larger by attaching sheetmetal to the original plate.
For kitchen vent, I used 6" round duct. I used vent that is wedge shaped, has 6" opening and round cover. The cover clacked in strong wind. I glued on 1" bolt washer and it seemed to help. I also attached a sheetmetal wind baffle on bottom, making sure the water does not pour into it and water can also drain. The cover does not clack as much but no solution will work 100% with these light weight vent covers. Hope this helps.
Thanks for that advice. I'm reconsidering the roof mount and may go ahead and put it on the gable even though the duct run is longer.
the one we always try to use is the Broan Roof vent for 3 1/4 x 10 or up to 8" round duct
never had a problem and we've been using that model for more than 20 years
when i have trouble finding them , i order a couple from Graingers
http://www.grainger.com/Grainger/items/2C504?cm_mmc=Google%20Base-_-Ventilation-_-BROAN-_-BROAN%20Roof%20Cap,%20Fits%20Duct%20Size%203%201%2F4%20x%2010%20In,%20Construction%20Material%20Steel,%20Black
the one i like is enameled steel and we often paint it to compliment the roofing color
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 6/21/2008 9:48 pm ET by MikeSmith
I have one of the Broan roof caps that you describe, and yes it is made very well with a nice epoxy, powder coat finish. But our roof is not very high pitch and the flapper would be facing in the direction where we get strong winds. I'm concerned that gusts will open the flapper and make a lot of racket on windy days, so I'll probably go with a gable vent made by Fantech and live with the longer duct run.