# high CFM range hood install



## s002wjh (Oct 11, 2016)

When installing high CFM range hood, the routing duct always should go up or flat, but never go downward??

also can I use dryer duct(lower elevation than range hood) to combine with my range hood duct? if so how do i prevent the exhaust from range hood split into dryer.

also any guide/link on how to install make up air unit?


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## nealtw (Oct 11, 2016)

Welcome the site.
Best go to plan B, If it's not against code it should be, if you did have a flapper or something that worked, what happens when both are being used.. You don't even want them close to each other where they exit the house. When the dryer is running it is sucking air out of the house, air will find the easiest way in to replace that air, when they are next to each other, they can suck air in the next vent bringing problem air back into the house.


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## Snoonyb (Oct 12, 2016)

s002wjh said:


> When installing high CFM range hood, the routing duct always should go up or flat, but never go downward??



The exception would be, if your venting appliance were a downdraft.

Most high CFM venting appliances will offer the remote blower option, which allows you to locate the motor away from the appliance, reducing the noise level and since you are exhausting products that will adhere to most surfaces, use smooth wall rigid venting material instead of the ribbed or flex-a-duct material.



s002wjh said:


> also can I use dryer duct(lower elevation than range hood) to combine with my range hood duct? if so how do i prevent the exhaust from range hood split into dryer.



Generally, dryer venting material will be far to small in area to handle the volume of a high CFM appliance and severely impact the latter's efficiency while creating the potential for a backdraft into the dryer.



s002wjh said:


> also any guide/link on how to install make up air unit?



Your local building code should be your guide for determining the ducting for the make-up air, some are very restrictive.


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