Vent Your Microwave Outside in 6 Steps

Having a microwave that vents smoke, odors, and moisture outside your home provides many benefits. It helps maintain better indoor air quality, prevents kitchen walls from collecting grease, and reduces noises and fan smells inside. While external venting does require some installation work, carefully following key steps will ensure it is done properly.

Whether you are installing a microwave in a new location or upgrading an existing one, these tips will set you on the right path.

Step 1: Assess Your Situation

Before installing any new microwave or venting, it is important to fully evaluate your current setup. This will determine the best positioning, necessary materials, and work required.

Determine the Best Location

Choosing the right exterior wall location is crucial for proper functionality and accessibility. The ideal location will:

• Be on an outer wall of the home without obstructions
• Allow ductwork to route outside with minimal bends
• Have sufficient wall space and studs for securing the microwave
• Not be near shaded areas or eaves where snow/ice accumulate
• Be conveniently within reach when cooking or using the microwave

Also consider your kitchen layout, traffic flows, and electrical or gas line positioning when deciding on placement. Positioning the vent about 12 inches above the microwave provides good capture of smoke and steam.

Identify Type of Venting Needed

There are two main types of microwave venting: recirculating and external. Recirculating vents filter and redirect air back into the kitchen. They recapture grease and odors, but do not remove moisture or airborne particulates. External vents require ductwork running outside, removing all air but requiring professional installation.

Match the ducting and airflow requirements of your microwave model (generally 150-300 CFM for standard models). More powerful microwaves need more substantial ductwork. Consult manufacturer guidelines to determine venting needs before purchasing.

Prepare the Necessary Materials

Once you have identified the ideal positioning and venting type, compile all the necessary materials and tools:

• Microwave with compatible exterior venting
• Venting duct materials (aluminum, plastic)
• Exterior wall cap and damper
• Mounting bracket, screws, toggle bolts
• Duct insulation
• Caulk and mesh screen for sealing
• Cutting/drilling tools for walls and ductwork

Having all equipment ready beforehand streamlines the installation process.

Step 2: Cut a Hole in the Wall

With materials prepped and positioning selected, the next key step is properly cutting a hole through the exterior wall for the venting ductwork. Carefully sizing and cutting this hole is crucial.

Follow Manufacturer Guide for Sizing

Microwave manufacturer instructions include specific duct size requirements and minimum wall hole dimensions. Precisely measure and mark the necessary width, height, and depth for the hole in your wall material (drywall, brick, etc).

Be sure to account for extra space all around the ducting to reduce vibration and allow room for insulation. A good rule of thumb is to make the hole at least 1 inch larger on all sides than the duct dimensions.

Choose Your Cutting Method

Several cutting tools can create clean vent holes through walls:

• Hole Saw: Spade bit for clean circular holes
• Keyhole Saw: Handheld saw for corners or oval openings
• Nibbler Tool: Punch tool for gradual snips into wall material

Mark your hole pattern from both sides of the wall. Cut the hole about one foot higher than the top of the microwave to properly capture rising steam and smoke.

Clean Edges and Remove Debris

File down any rough plastic or metal edges around the freshly cut hole. Use a vacuum cleaner and shop brush to thoroughly remove all debris surrounding the hole area.

You want an empty, smooth space for running vent duct materials. Any leftover debris could clog or disrupt airflow.

Step 3: Install the Venting Ductwork

Passing suitable ductwork from the microwave through the wall and outside is imperative for proper functionality. The right materials and connections keep airflow smooth.

Select Appropriate Duct Type

Three main duct types work for effectively venting microwaves:

• Rigid Metal: Provides best airflow, durability
• Semi-Rigid Metal: More flexibility in routes
• Flexible Plastic: Easy to install in tight spaces

Match the necessary duct dimensions and material for your microwave model. Most external venting uses rigid 4-6 inch aluminum or galvanized steel ducts. Try to minimize sharp turns or kinks that could trap grease or lower airflow.

Attach Duct through Wall and Outside

Run duct through the freshly cut hole, using sleeves and elbow joints to tightly seal connections. Attach flanges secure the duct endpoint outside using exterior screws or silicon. Verify a tight straight-through connection from microwave to outdoor vent cap.

Avoid leaks which could blow hot air back inside wall interiors. Use metal strapping as needed to anchor long horizontal duct runs.

Insulate the Duct Properly

Wrap all metal ductwork running to the outside with insulation rated for exterior use. Fiberglass duct insulation works well to absorb condensation and prevent energy losses through the ducts themselves.

Proper insulation also dampens fan and airflow noises for a quieter kitchen environment. Secure insulation tightly using latex-coated metal duct tape. This complete seal prevents dusty buildup or mold inside ducts.

Step 4: Prepare the Microwave

With underlying infrastructure now ready, the next phase is acquiring and prepping your new externally-vented microwave itself for installation.

Purchase Correct Microwave Model

If replacing an existing microwave, select an upgraded model specifically designed and rated for exterior ventilation. Consider size, dimensions, vent style, and cooking features alongside the aesthetic fit within your kitchen.

Stainless steel, black, or white finishes match most decors. Ensure your over-the-range, built-in or countertop microwave dimensions match the allocated kitchen space.

Remove Light Bulbs and Turntable

To simplify mounting later, remove any light bulbs or glass cooking trays from inside the microwave. Detach interior turntables or racks that could shift around during positioning.

This protects internal microwave parts from damage while giving you full access for top-down installation. Re-install them after anchoring the appliance up securely.

Follow Grounding Instructions

Always ground microwave ovens properly through provided grounding terminals or lead wires. This crucial safety step protects users against potential electric shocks from current leaks in the appliance.

Use grounding clips to connect green wires to grounded metal studs or alernatively attach grounding screws through the microwave frame into a grounded wall box.

Step 5: Mount the Microwave

Hoist the prepped microwave into place, lining up the back-end vent outlet with your ducting route. Securely fasten the appliance into the wall cavity through precise mounting procedures.

Position Microwave in Place

Lift or tilt the microwave into the opening, carefully lining up its back-end exhaust vent with the vent duct connector. Slide into place slowly, ensuring the top tilts back and bottom clears countertops.

Confirm the microwave sits evenly and level at the desired height before releasing. Have helpers to hold it temporarily in place if needed.

Secure Mounting Plate to Wall

With the microwave loosely resting in the opening, attach vertical mounting rails or a horizontal mounting plate anchored into the wall itself.

Use toggle bolts for drywall or wood screws drilled into wall studs, following weight bearing specs. This reinforced bracketing provides a sturdy foundation to permanently hang the microwave.

Attach Microwave to Mounts

Finally, hook the microwave vent openings into wall mount slots, letting the full weight settle on its anchoring. Microwaves with keyhole brackets simply slide over screws to hang in place.

Alternatively, drive additional screws through the microwave top casing directly into the upper wall plate or side brackets for an even more rigid hold.

Step 6: Complete the Installation

Finish securing all connections and openings to cap off safe microwave and vent installation with reliable functionality.

Connect Vent Ductwork

Join the microwave's exhaust vent duct connector to the outlet of your routed ductwork. Carefully align for smooth airflow before tightly clamping connections in place using zip ties or metal tape.

Verify duct joints include gaskets and fit snugly to prevent leaks around the exhaust transition areas.

Seal Exposed Areas

Use high-temp caulking or silicone sealant around the ducting hole and microwave casing. Ensure back vents align well with walls with no exterior gaps. Foam backer rods help fill spaces tightly.

Spray foam insulates and blocks holes, but avoid overfilling duct spaces. Duct tape and mesh further protect vent seals against pest entry from outside.

Test Fan Functionality

Turn on the microwave ventilation fan settings, checking for smooth and quiet airflow out the external duct. Verify the damper flap opens when running, preventing backdrafts.

Balanced airflow and an airtight seal confirm well-mounted ducts ready for smoke and steam venting during microwave cooking.

Safely directing microwave ventilation outside brings clearer kitchen air and prevents buildup of smells, smoke, and moisture on walls or ceilings. While the process requires precise placement and ductwork, following reliable installation steps creates effective and long-lasting external venting.

Assess your situation, create needed infrastructure, mount components securely, and thoroughly test connections. With care taken at each phase, external microwave ventilation boosts functionality for an improved cooking experience.