"Snuffy "Hub Cap" McKinney" wrote in message ...
"Snuffy "Hub Cap" McKinney" wrote in message news I need to convert a range hood that is venting both up the vertical duct and into the room, to just venting up to the duct. In the photo, the room vent is seen on top of the hood.

http://www.nutone.com/common/seriesi...b-9600eae64e73

I have looked inside at all angles, and the squirrel cage fan is plenty strong enough to vent only up the duct. There is an assembly connected between the outlet of the fan to the top of the hood that directs some flow through the vent in the top of the hood into the room. But I don't see any way to close it - at least without taking things apart. No manual and searching the series number turned up nothing at www.broan.com.

Seems odd to me, but in any case, anyone ever seen this type of setup before?

Info from mfr plate:
Broan Allur Model QS1 Rev E, Mfd 2006, 1.8A, Hi/Low 110/220 CFM

Thanks buddies!

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I just got around to fixing this hood. After getting the manual, it was 5 screws to remove the access panel holding the lights and one screw to remove the "air chute" (exhaust diverter). Inside the diverter the baffle had been inserted to blow air out into the room thru a vent in the top of the hood. It was simple to pull the baffle piece out, flip in around and keep the exhaust inside the duct.

I thought about just putting a piece of sheet metal over the opening in the duct, but didn't want to spend the time if it worked.

Reassembled and there is still a slight flow out of the vent into the room, and also some air flowing out around the lights, although both are lower than before. Still I don't want ANY exhaust coming out in the room. That defeats the whole purpose of having a vent fan.

I strated looking at where the air was coming from. The fan is fixed to a rotating housing, and the housing has a lip -- hard to describe -- on the bottom. So that when the exhaust starts to back up, it can flow back around the outside of the fan housing and down toward the stove top. The way the lip is curved, it forces the back pressure out away from the fan blade and it comes out back down thru the filters and toward the stove top. It also flows up and out the openings for the lights.

I looked up thru the fan and it looks pretty clear all the way to the top.

Now I'm starting to get ****ed. Seems to me the outlet of the van should be sealed so that any back pressure will not come back down into the kitchen. If that's a safety issue, they could have put a spring loaded relief vent instead of leaving that path completely clear.

I know there is always going to be exh leaking back around the blades, but I think this might be a bad design in this case.

Any comments about this?

****

The other comment is that instead of the lip on that fan housing being outward, if it were straight, any back pressure exhaust would flow straight down and be pulled back into the fan.