# Top front vents in OTR microwave - do they matter



## andyscott (Oct 14, 2014)

if you are venting outside (through the roof), not recirculating?

The reason I ask because with our new kitchen cabinets that have 15 1/2" depth (including the door), the vents at the top front of the microwave get blocked. Does anyone know if blocking/covering these vents matter if you are venting out (through the roof), not recirculating? 

What's confusing is the the installation guides for both GE and Whirlpool microwaves say that a cabinet depth more than 12-13" won't work, but the guides don't make a distinction between recirculating and outside venting. 

Unfortunately, the customer service people on the 800 lines are trained to read only from the installation guide. On the old GE OTR that we have currently installed, these vents are also top front facing you, but on all the new models from every manufacturer they face the ceiling (so the vents will be covered/blocked by the depth of our wall cabinets).

Because we have a narrow kitchen, I don't really want to add a filler piece like a 2x4 at the back that will make the microwave stick out even more than the 15 1/2" cabinet depth (including door).


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## Colbyt (Jan 27, 2014)

I don't know, but, if you rotate the fan housing for outside exhaust and there is no air coming out the internal vent, I would go for it.


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## SPS-1 (Oct 21, 2008)

If you have 400 cfm exiting the back or top of your microwave, you gotta have 400cfm entering your microwave somewhere. That could very well be a an air inlet. You already have the microwave, right ? Turn on the fan and put a tissue near the top front. My Panasonic had the same warning on cabinet depth (but luckily, my cabinets were within spec).


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## hardwareman (Oct 9, 2010)

for venting it purposes it will not matter. The only reason I would not suggest doing it is because it may help keep the components like the magnetron cooled.


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## Yodaman (Mar 9, 2015)

andyscott said:


> Because we have a narrow kitchen, I don't really want to add a filler piece like a 2x4 at the back that will make the microwave stick out even more than the 15 1/2" cabinet depth (including door).


I can not answer your question definitively but will comment on one aspect of your post. Since micro/vent is positioned over the cook top that has a depth of approx 26", is a 3" build out really an issue. After all it wasn't when you decided on a 3" extra deep cabinet.

Maybe a local service man would be of more use than the help line.

Good Luck


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## SPS-1 (Oct 21, 2008)

Yep, that's the air inlet. On mine anyways it is -- I would bet yours is the same.


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## andyscott (Oct 14, 2014)

Thanks all for your responses. I will definitely check with a local service guy. If I'm not exhausting over the stove, and run the microwave, is there any reason why the microwave would need to suck in air?


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## Colbyt (Jan 27, 2014)

It is possible that when the fan housing is rotated the in room exhaust serves as additional intake. In an unvented position the air comes in the bottom and out the top on every one I've even seen.

No one is going to contradict what the printed manual says. You are home alone and testing your wings as a 'field engineer'.

I stand by what I said above, "rotate the fan and monitor the airflow". A cigarette or smouldering piece of papers shows visible patterns.


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