How to Install a Vented Microwave


Installing a vented microwave is an important kitchen upgrade that allows you to vent steam, grease, and odors from cooking out of your home. A vented microwave is connected to a duct that leads outside, helping improve indoor air quality and preventing grime buildup on kitchen surfaces. While vented microwaves require a bit more planning and effort to install than non-vented models, the benefits are worth it. This comprehensive guide will walk you through the entire process of installing a vented microwave, from choosing the right model to connecting the ductwork. Follow these steps and you’ll have a powerful, efficient vented microwave installed in your kitchen.

Step 1: Choose the Right Vented Microwave Model

The first step in installing a vented microwave is selecting the right model for your needs:

  • Size – Consider the dimensions of your existing oven opening to ensure proper fit. Common vented microwave sizes include 30” wide, 1.5 cubic feet capacity models.
  • Venting style – Microwaves are available with front, rear, or top venting abilities. Choose one that aligns with your current or planned ductwork.
  • Microwave wattage – Vented models are available from as low as 600 watts to 1250 watts or more. Choose a higher wattage for faster cooking times.
  • Features – Look for sensor cooking, multi-stage programming, smart options like Alexa connectivity, turntables, interior lighting and more.
  • CFM – The CFM (cubic feet per minute) measures ventilation power. Look for at least 150 CFM for effective moisture removal.

Once you select the ideal vented microwave based on your kitchen space, cooking needs and features, it’s time to check existing electrical connections.

Step 2: Ensure Proper Electrical Setup

Vented microwaves usually require a dedicated 120V, 60Hz, 15A electrical connection. Start by turning off power at the circuit breaker. Remove the existing microwave and examine the electrical setup:

  • There should be a 3-prong receptacle visible inside the cabinet. If not, wiring modification is required.
  • Confirm the receptacle provides a grounded, 120V connection able to support a 15 or 20 amp electrical load.
  • If the receptacle is 2-prong or the wiring is too light for a microwave, contact an electrician to upgrade wiring.

Proper microwave electrical supply is essential. Don’t install the appliance until any wiring issues are corrected.

Step 3: Inspect Ductwork Path and Ventilation

An exhaust fan pulls cooking fumes from the vented microwave outside through ducting. Carefully inspect this ductwork path before installation:

  • Ductwork should lead directly from the oven cabinet space outside with as few turns as possible.
  • Confirm ducts are made of rigid metal, not plastic. Flexible metal ducts should only be used for short transitions.
  • Check that existing ducts are clean and clear of grease buildup or blockage.
  • Ductwork should terminate outside with an exhaust hood/damper assembly that prevents backdrafts.
  • If venting path is too long or convoluted, microwave ventilation will be poor. Have a contractor simplify or improve ducting.

Ensure adequate CFM rating for existing duct length. Longer or restrictive ducting requires higher CFM for proper ventilation.

Step 4: Create the Right Opening

Vented microwaves need proper cabinet space and clearances. Follow manufacturer guidelines to create an ideal opening:

  • Cut an opening in bottom or top of cabinet to allow for exhaust vent.
  • Remove adjacent cabinet doors or shelving if needed to accommodate microwave.
  • Confirm at least 2” of clearance around top and sides of oven cutout. This allows room for proper ventilation.
  • Wood blocking may need to be added around the opening for proper microwave support. Consult instructions.

Take accurate measurements and create a carefully sized opening for a flush, secure fit. This helps the vented microwave operate safely and efficiently.

Step 5: Install Ductwork and Ventilation System

With an adequate opening ready, it’s time to install or connect the ductwork:

  • Attach any provided ducts to exterior damper/vent hood, sealing joints with aluminum tape.
  • Connect microwave exhaust port to existing or new ductwork with tape. Make sure connections are tight.
  • Position damper assembly/hood outside home through exterior wall or roof. Seal exterior openings thoroughly with caulk.
  • Use rigid metal ducts and minimal flexible duct to create a smooth path outside with minimal bends.

Proper duct installation helps moisture, grease and odors easily vent outside. This prevents buildup on kitchen surfaces and also helps eliminate cooking odors inside the home.

Step 6: Mount the Vented Microwave

You’re now ready to mount the new vented microwave in place:

  • Place microwave inside opening, verifying trim kit or edges align flush with cabinetry.
  • Attach mounting bracket securely to interior cabinet bottom or wall depending on microwave type.
  • Install filters if required. Consult manual for any model-specific filter placement.
  • Secure microwave to bracket using provided hardware. Do not overtighten!
  • Connect vent ductwork attachment snugly to exhaust port on oven rear/top.
  • Ensure appliance is level and has proper ventilation clearance all around.

With the microwave installed in the prepared opening, it should fit snugly while allowing room for air circulation.

Step 7: Complete Electrical Connections

Here are the remaining electrical steps to properly connect your new vented microwave:

  • Plug 3-prong electrical cord into grounded outlet, or connect wiring to junction box as required.
  • Restore power at circuit breaker. Verify interior oven light comes on when door is opened.
  • Test any multi-speed venting. Air should blow through filters from interior to outside.
  • Refer to product guidelines and connect any other model-specific items like wifi antennas.
  • Set the new clock time before use.

Take care when making all electrical connections. Double check wiring diagrams in instructions if needed.

Step 8: Test and Use the New Vented Microwave

It’s time to test your new installation!

  • Heat a cup of water to verify interior microwave function.
  • Activate vent fan while cooking something aromatic like popcorn or fish. Confirm odors are properly exhausted outside.
  • Inspect the exterior termination while venting is on high. No steam or moisture should be visible escaping.
  • Check for vibration noises while both microwave and venting are in use. Adjust or tighten as needed.
  • Read manual for any other model-specific tests to perform.

Let the vented microwave run for 10-15 minutes continually to verify all parts are working correctly before full use. Enjoy easier steaming, defrosting and cooking with built-in ventilation!

Frequently Asked Questions About Installing a Vented Microwave

Installing a vented microwave is a multifaceted process that raises many questions. Here are answers to some of the most frequently asked installation FAQs:

How difficult is it to install a vented microwave?

Vented microwave installation has a medium level of difficulty, assuming you have adequate electrical capacity and existing ductwork. Hooking up ducting through cabinets requires handy skills. Hiring a professional is recommended if you lack experience.

What tools do I need to install a vented microwave?

Common tools needed are: drill, stud finder, keyhole saw, duct tape, screws, pencil, utility knife and cordless screwdriver. Always wear safety glasses during installation.

What if my cabinets don’t have an existing opening?

Use a stud finder to mark stud locations first. Then carefully measure and cut an opening in the cabinet bottom or rear large enough to accommodate the microwave.

How long does a vented microwave install take?

If electricity and ductwork are already in place, typical install time is 2-3 hours. Allow more time if ducts need adjustment or cabinet modification is required.

Why does my new vented microwave have weak airflow?

Subpar airflow usually means improper ducting or vent termination. Confirm all connections are tightly sealed and ducts are free of kinks. Also check damper assembly outside to ensure backdrafts can’t occur.

Do vented microwaves require special maintenance?

Clean the exterior filters 1-2 times per month. Also inspect the ducting annually for any buildup or debris that needs removal to maximize ventilation.


Upgrading your microwave to a vented model requires planning but pays dividends through better cooking environment and air quality. Correctly measuring your opening, providing adequate electrical supply, connecting ductwork and carefully installing the new microwave are the keys to success. Following this guide helps ensure your new vented microwave will provide powerful ventilation for years of reliable cooking performance.