5 Venting Issues When Installing Your New Built in Microwave

Are you installing a new built in microwave for the first time? Before you rip the box open, take a minute to make sure you have checked out the area where you will be installing the microwave first. Over the years I have helped many customers who have entered the fabrication shop looking for duct fittings needed to vent their brand new microwave oven.

Here are five of the most common venting issues they have conveyed to me.

1. Cabinet space above is never big enough

The cabinet above your microwave is notoriously tiny. Obvious reasons are because of ceiling height and most of our homes aren't blessed with 12' vaulted ceilings. If you happen to have ample space where your new microwave will live, then you probably won't have these issues. Either way, the space provided most of us for venting your brand spanking new microwave is extremely tight, leaving limited space to vent the appliance properly.

2. Manufacturers don't provide venting accessories of any kind

Nothing's as easy as they make it seem in those Home Depot or Lowe's commercials where the couple stroll into their friendly neighborhood warehouse and find exactly what they're looking for. They take it home, it fits perfectly into place and both stand back in glorious satisfaction. 

Sadly, this is not how it usually happens in real life. During the project you will inevitably run into some issues while installing your new hanging microwave. Especially because the manufactures of  your new microwave have no accessories for installing the vent duct to the outside of your house. They give you some basic direction, leaving it up to you for the rest of the installation. Obviously this is a major problem when trying to finish what seems like such a simple installation.

3. Manufacturers always have a rectangular outlet for venting

Another major issue, related to no accessories, is the outlet for the vent on your new microwave will almost assuredly be rectangular. Why is this such an issue? Well, the answer brings me to number four.

4. Most stock venting is round

If you're hooking your new vent to an existing vent, there's a good chance the already installed duct is round. Or if you take a trip to the local hardware store, the majority of new duct and duct fittings for venting will be round. You may find some square to round duct fittings, but it's a crap shoot on whether or not you will find the size--usually 3 1/4" x 10"-- of the outlet vent on your brand new microwave.

Again, the issue when trying to install your vent in such a small cabinet. The more fittings you use, the more space is taken up. There's only so much to go around.

5. Keeping the vent rectangular means custom made

If the existing vent does happen to be rectangular, there's an even better chance the sizes of each will be completely different, leaving you looking for shops like mine to have a custom transition fabricated.

Many times this will be your best solution due to lack of resources, especially if you are a laymen when it comes to a project like this. One fabricated duct piece is much easier to fit inside your tiny cabinet rather than two or three from Home Depot. And, the cost savings is immense if you are able to find a custom fitting because the alternative is hiring someone to install the microwave for you.

Now, if you are installing the microwave in a new home or for the first time in your older home there are many more options. What do I mean by this? Well, you may have enough room to buy a stock square to round fitting and run the rest of the vent round. Or you may be able to use the stock rectangular duct from the hardware store to run the entire vent. 

No matter what your situation, taking the time to map out the project to avoid these pitfalls is always a good rule of thumb. 

Good Luck! 

Do you need a custom transition for your built in microwave vent? We can help! Visit our contact page to get in touch with the fabrication shop. 

Posted on October 16, 2013 and filed under Duct Tips, Fabrication, Sheet Metal.