When buying kitchen appliances, one of the most common concerns is ventilation. Things aren’t that much different when buying a microwave. So, do microwaves need to be vented? Especially the built-in type or the over-the-range ones?
Not all microwaves need ventilation. Proper clearance suffices for most built-in models – these microwave ovens have built-in fans that prevent overheating. However, most over-the-range microwaves require additional venting. External venting may also be required by the building codes in your state.
Before delving into the matter and discussing over the range of microwave oven ventilation, we should make the distinction between ventilation and clearance.
Clearance is the amount of empty space you should keep around the microwave. All microwave ovens – regardless of their type – require some clearance. Clearance ensures airflow and prevents motor overheating.
As a rule of thumb, countertop microwaves need at least three inches of clearance on both sides and on top, and about an inch of clearance in the rear. Built-in microwaves generally require about an inch of clearance on all sides, including the rear.
When it comes to built-in microwaves, you should know that trim kits are designed to ensure proper clearance on all sides.
Over the range microwaves also need about an inch of clearance in the rear and at least 30 inches between the stove and the bottom of the oven.
Clearance aside, over-the-range microwaves generally incorporate fans and filters designed to replace the range hood. Some of these models need ventilation; some don’t. Let’s find out more about it.
Most OTR microwave ovens nowadays replace recirculating range hoods that work with charcoal filters. These range hoods (and microwaves) are ductless, meaning that they do not require duct vents and external exhaustion.
Some over-the-range microwaves are equipped with powerful fans designed to remove heat and steam from your kitchen.
These appliances require external exhaustion; thus, you should have duct vents installed – or the possibility to install them if your house doesn’t have them already.
The international plumbing code doesn’t have specific venting requirements when it comes to over the range microwaves. The only requirement regards the clearance between the stove and the bottom of the unit, which should be of no less than 30 inches.
However, the code may require you to use a range hood that exhausts fumes to the outside of the building.
In this case, you must install an over the range microwave with an external exhaust vent, whether you like it or not.
As far as the building code is concerned, you should know that all range hoods are required to discharge to the outdoors through a duct. The only exceptions are ductless range hoods installed in kitchens that have natural or mechanical ventilation.
In other words, if your kitchen has no windows and no extractor fan, you have no other option than to install a ducted over-the-range microwave if you want to replace the range hood with a functional cooking appliance.
As explained above, there are two over-the-range venting options: recirculating and external venting. Each comes with their own benefits and drawbacks. Let’s have a closer look at them.
Recirculating And External Venting Systems
Recirculating venting systems use charcoal (or similar) filters to remove odors and trap steam and cooking grease. However, they do little to remove hot air and get rid of air moisture. These ductless venting systems work great in kitchens where installing a duct vent is not possible – but only as long as the kitchen benefits from proper ventilation, such as windows or an extractor fan.
External venting systems use ducts to conduct cooking fumes and hot air out of your house. This system type provides excellent performance. However, you’ll have to install ducts that go from the microwave oven above the cabinets and out of your house through the wall or roof. If you don’t have a range hood duct already, installing one takes time and is costly.
Microwave Venting Benefits And Drawbacks
Recirculating Systems Benefits
- Easy to install
- No additional work is required for installation
- Quiet operation
- Easy maintenance
Recirculating Systems Drawbacks
- Charcoal filters need replacement
- They don’t remove the warm air
- Lower overall performance
External Venting Benefits
- High efficiency
- Remove grease, hot air, and moisture
- They don’t require additional ventilation (such as windows or an extractor fan)
External Venting Drawbacks
- Duct installation is messy and costly
- The duct may pass through an upper cabinet (or more)
- Microwave ovens with external venting consume more energy
Choose A Recirculating Venting Microwave for Flexibility
Have you just moved into a new home and plan to remodel your kitchen soon? If you don’t have a duct vent and are not sure if you want to keep the range in the same place in the future, and over-the-range microwave oven with recirculating venting is your best bet.
This venting option gives you the flexibility to move the range (and over the range microwave) to a new spot without worrying about relocating the duct vent.
Opt for External Venting If You Cook A Lot
While recirculating vents are ideal if you need flexibility (or can’t install duct vents for one reason or another), external vents are your best option if you’re cooking a lot. As explained above, a charcoal filter removes odors and some grease and moisture. However, it can’t deal with lots of steam properly.
Always Follow The Manufacturer’s Instructions
One of the most important things to keep in mind when installing any kind of microwave oven is that you must follow the instructions in the user manual.
Does the manual require a specific clearance? Respect it. Does it require specific maintenance? Do as the manual says. Not only is this recommended for warranty purposes, but it will actually help you keep your appliance in good working order for longer.
Make Sure There Is Sufficient Distance Between Stove and Microwave
When installing an over the range oven, the building code requires you to maintain a clearance of at least 30 inches. However, the building code doesn’t account for things such as large pots and tall cookware.
You should also know that vertical distance isn’t the only thing that matters. If you have a countertop microwave, place it at a distance from the stove. This will prevent overheating.
Microwave Venting Related FAQs
Is it safe to put the microwave in a cabinet?
Yes, it is safe to put a microwave in a cabinet, as long as you have a built-in model. Most countertop microwaves are suitable for a built-in installation. Microwave ventilation is not needed (these models have built-in fans that keep the motor cool), but you must respect the clearance requirements in the instruction manual.
If you want to place a countertop microwave on a shelf or inside a cabinet, you should consider adding microwave in-cabinet ventilation. This is different from a range hood and refers to fans or holes in the cabinet that ensure proper airflow.
Should I purchase a vent hood or microwave vent hood?
It depends on your needs. If you cook a lot and need a powerful range hood, go for a standard model. Range hoods are almost always more powerful than microwave vents.
If you have a small kitchen and want to save some counter space, a microwave vent hood can help you kill two birds with a stone. However, if the appliance requires outside venting, the built-in microwave ventilation (the duct) passing through the cabinet might void the purpose. Thus, you should consider a recirculating microwave vent hood.
How to tell if your microwave is vented outside?
It is generally easy to tell whether your microwave needs outside ventilation by inspecting the unit. If you notice an opening with a latch designed to be attached to a duct vent, your microwave requires outside ventilation.
If you’re not sure, consult the user manual or contact your brand’s customer support. An electrician or contractor might also help.
Can you replace a vent hood with a microwave?
Yes, you can replace a vent hood with a microwave. However, you can only replace it with an over the range model (with included vents) and only if the distance between the top of the stove and the bottom of the oven is at least 30 inches.
Despite these requirements, know that you can replace both a ducted or ductless range hood with an OTR microwave.
How much space do you need around a convection microwave?
You should leave about three inches of clearance on the sides and above and one inch of clearance at the back of the microwave. If you have a built-in model and install it with a trim kit, you have nothing to worry about. Trim kits are designed to maintain the required clearances.
Not all microwaves need to be vented, but an over-the-range microwave might require outside venting.
The most important thing, however, is to respect the clearance requirements to prevent hazards and keep your appliance in good working order for a long time.