I need my ventilation to suck
November 3, 2008 3:28 PM   Subscribe

Do over-the-oven microwaves with exhaust inherently suck? (no pun intended)

I moved into a house that has one of these and this is my first experience with one. It is connected to a duct and vents to the outside. The problem is that it hardly moves any air at all. Last night I cooked a beef fillet and the kitchen area filled with smoke. I like cooking and roasting coffee often, so this is a problem that I need to address ASAP. From some cursory googling, many people seem to think the microwave exhausts are inherently crappy - that is, they will never move as much air as a proper hood. Is this really true? What are your experiences?

I have no problem replacing the whole thing with a proper hood then just doing a counter-top microwave, but if I can get away with an over-the-oven version that works effectively, I'd prefer that due to the space savings.
posted by jclovebrew to Home & Garden (14 answers total)
I have an IKEA microwave/vent hood and it works fine. When my contractor installed it, he noted that the engine on the vent was strong and it vented the air the 6 feet to the exterior of the house.
posted by bove at 3:41 PM on November 3, 2008

Check the filter.
posted by stubby phillips at 3:43 PM on November 3, 2008

I have a GE microwave/vent combo, and although it's as loud as a jet engine it works fine. It's not as powerful as a decent vent hood (note the use of the word "decent" in there -- plenty of vent hoods suck ass), but when something burns it works like a charm.

Something is wrong with yours.
posted by aramaic at 4:05 PM on November 3, 2008

I'll second what aramaic said. I have a GE profile microwave hood and it works well. I think the fan has 4 speeds and be quite loud on the strongest setting, but it does suck up anything that might be smoking on the stove or the oven.

Yes, it wouldn't hurt to clean the filters if they are gummed up. Or perhaps the venting beyond the fan is blocked?
posted by csw at 4:18 PM on November 3, 2008

here's how to check the filter: take it out and turn on the blower.

big difference? clean the filter
nasty ooze dripping from filter? clean the filter.

no significant ooze or suck differential? check the vent.
posted by stubby phillips at 4:21 PM on November 3, 2008

Sometimes they're not vented to the outside. Clearly, this affects performance.
posted by electroboy at 5:01 PM on November 3, 2008

The filters are clean. They might even be brand new because they're really clean. Or maybe they're just clean because nothing really flows through them.

I guess I'll start with taking the whole rig down and checking if there's something major/obvious wrong between the microwave and the duct, or in the duct itself.
posted by jclovebrew at 5:03 PM on November 3, 2008

When the fan isn't on, do you feel any air coming from the duct? Could be an air imbalance in the house creating more negative pressure in the kitchen than in the duct, preventing it from properly exhausting.
posted by bizwank at 5:22 PM on November 3, 2008

Sometimes they're not vented to the outside. Clearly, this affects performance.

mine is not. which immediately made me question the point of the vent in the first place.
posted by namewithoutwords at 5:33 PM on November 3, 2008

Assuming it is vented to the outside, make sure that duct is as large as it's supposed to be. If the hole exiting the hood is 6" in diameter, the duct should be 6" across all the way to the outside. If the installers reduced it to a 4" duct, the airflow will be very restricted.
posted by jon1270 at 5:55 PM on November 3, 2008

Mine works fine.
posted by serazin at 6:31 PM on November 3, 2008

mine is not. which immediately made me question the point of the vent in the first place.

There's little to none. Some of the grease gets filtered out, but it's pretty negligible. I lived at an apartment where the vent blew the smoke straight into your face when you were standing at the stove.
posted by electroboy at 7:18 PM on November 3, 2008

Make sure when the unit was installed, that the installers did whatever was necessary to switch it from non-vented to vented mode.

Most over-the-range units have two configurations; in one they suck air from below, run it through some "filters," and then blow it out a vent above the microwave back into your kitchen. In the other configuration they suck air in and blow it out the vent. Generally, some sort of sheet-metal panel needs to be removed or installed to change from one to the other.

It's entirely possible to leave both exits blocked, in which case the thing won't work at all, or to leave it in non-venting mode, in which case it will work very poorly (since it doesn't really exhaust). So that would be something I'd check. You'll need to get at the installation manual to figure out how to check it, though.

One easy check would be to turn on the blower and see if it's blowing air out the grille above the microwave (this is where the non-venting outlet is on my GE model). If it is, then the unit is probably not set up for use with a vent.

If you can take the unit out completely, then another easy check would be to start up the blower and make sure air actually comes out where the vent is supposed to attach; that'll at least tell you if it's a problem in the vent or the microwave.

I've seen on various home-improvement shows that there are in-line vent fans that can be installed...if all else fails, especially if your vent line is particularly long, you might see if one of these would be appropriate (need to get one specifically for kitchen exhaust, not bathroom exhaust). That would require a separate switch and be a fairly big HVAC and electrical project, though.
posted by Kadin2048 at 9:27 PM on November 3, 2008

Seconding everything said above and adding that I have GE profile that works great! It kept our kitchen cool over weeks of canning tomatos and peaches.
posted by buttercup at 9:31 PM on November 3, 2008

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