October 12

Convertible vs Recirculating Microwave Vent | Is Internal or External Ventilation Better?


Author: Cornelia Suehr
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Shopping for a microwave oven (or convection microwave oven) means getting to grips with a widFe variety of different appliances. From basic models for the kitchen countertop to over-the-range microwaves and all sorts of built-in and convertible microwaves, there’s no shortage of options available.

Technically speaking, microwave ovens are designed with the same basic purpose in mind. A good microwave can not only supplement a kitchen stove as an energy-efficient device for quickly and conveniently heating almost anything, but as an aesthetic statement, as well, which these retro ovens are prime example of.

Our Recommended Microwave Oven

  • It has ten power levels with multi-stage cooking
  • Ideal small-space solution
  • Easy-to-view interior lighting

But when it comes to the ventilation system microwave ovens use, there are two very different microwave categories available. One of which is the recirculating venting system, the other is the external venting system. Both these systems are incredibly silent, and if you do here some noises, they probably come from other pasrts of the microwave, such as motor, or various alarms, as we already explained in a post we shared earlier (see here what to do about the annoying beeping noise, too.)

Convertible vs Recirculating Microwave Vent

As for which is better – it’s less a case of personal preference, more a case of which type of electric oven you choose. Recirculating venting vs. external venting is more about the type of microwave in question, as opposed to anything to do with its performance or desirability. For that matter, you can even cook food for a microwave oven without needing one as explained in other post.

In any case, convertible microwaves and convection microwaves are available, which come with the option of using a recirculation kit to switch from one venting option to the other.

woman microwaving vegetables

Venting Kitchen Fumes

A microwave cooks food (see here if such food remains nutritious) microusing thermal energy or hot air in the case of a convection microwave oven. It is a great addition to a kitchen because of its ability to prepare and reheat foot faster and its better versatility compared to traditional ovens, though it comes with higher price (see 'Are Convection Microwaves Worth It? post).

 Irrespective of whether the oven is using electromagnetic radiation, superheated air at the time, or sensor cooking, explained here, fumes inevitably build up inside the device.This is why microwave vents are a standard feature on every microwave oven – an external venting system of some kind to release the fumes from within.

For the most part, the airborne particles released by microwaves are not particularly hazardous. Most microwave ovens feature some kind of filtration system designed specifically to ensure that the fumes released do not pose a threat to those in the vicinity. On another note, some food, like grapes, when put in the microwave could trap electromagnetic energy which will eventually break down in a flash, causing sparks inside the microwave, which could lead to serious consequences.

Nonetheless, when it comes to external venting options, they are considered preferable by some - as an effective way to filter kitchen contaminants. 

smoke in the kitchen

Range Microwave vs. Ductless Recirculating Vent

In a nutshell, a microwave oven designed for exterior venting is connected to a duct that leads outside. This means that the microwave is able to release steam (and also removes smoke where necessary) through an external venting system and duct.

Meanwhile, a basic microwave oven with a standard built-in ventilation system (i.e., recirculating venting) simply releases the air into the surrounding space. There is a filter and fan built into the appliance, enabling it to discharge steam, air, and smoke as necessary while cooking food in a microwave oven

In addition, when it comes to safe use of microwave, in this post we went over the different types of materials that you can use for cooking inside a microwave. You must have heard that putting metal in a microwave is a not such a good idea. We also explained here how to safely deal with an old microwave.

oven and microwave

What is a Convertible Vent Type Microwave Oven (or Convertible Convection Microwave Oven)?

As the name suggests, the term convertible means that a microwave or convection microwave oven can be converted from venting to non-venting ducting modes, if required. Doing so means finding the appropriate recirculation kit part number, placing an order with an authorized parts distributor, and conducting a little DIY.

As for why you may wish to switch to the recirculating venting option, it’s something that may be necessary if looking to reposition your microwave. What’s important to remember is that virtually all building codes state that external venting is mandatory for an over-the-range microwave. It is a formal legal requirement to have the appropriate ventilation system installed in order to deal with the fumes produced by an over-the-range microwave oven.

man cleaning vent

A recirculating venting system wherein the microwave vents internally is therefore not an option with these types of appliances.

Nevertheless, those who own range microwaves may decide at a later date to reposition the microwave oven. They may choose to move it away from the kitchen stove and place it somewhere on a countertop – away from the stovetop surface.

At which point, it no longer needs to be hooked up to an external venting system or duct. A recirculating kit can be used with a convertible microwave to channel the emissions safely back into the kitchen.

Something that could prove significantly cheaper than purchasing a new microwave oven outright. Particularly if you bought the best microwave, you could afford it in the first place, which in the case of external venting microwaves can be quite expensive.

Our Recommended Microwave Oven

  • It has ten power levels with multi-stage cooking
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External Venting System Vents Installation Costs

Deciding between the two types of microwaves is actually quite simple for most households. As touched upon above, microwave ovens designed to be positioned above the stove need to be connected to be ducted to the outdoors. There’s no alternative option available – these are specialist microwaves that can only be installed in certain locations.

Still, it can represent a more cost-effective option than installing a range hood from scratch, given how the microwave pulls double duty.

Elsewhere, a basic microwave can be positioned anywhere in the kitchen. If external venting via a duct simply isn’t an option, this is really the only realistic choice available - see best microwaves to use at home.

cost is higher

Range Hood Duct Installation

While it is perfectly possible to have an external vent installed, it has the potential to be a costly and disruptive process. Along with the equipment required to install your microwave, you will also need to hire somebody to cut a hole in your exterior wall.

Depending on the type of microwave you’re looking to buy, the costs of installing the vent could significantly outweigh those of the appliance itself.

Hence, standard countertop microwaves are generally the recommended option for most kitchens – see Hamilton Beach - particularly where there is no range hood already installed. If you have a range hood and decide to go with the external venting option, consider a convertible microwave if you change your mind.

kitchen hood

A Look at Standard Countertop Microwaves

The countertop microwave is the standard, traditional appliance most people choose for their kitchens and can last a long time if taken care of well as explained here. They offer a wide variety of power levels and are designed to release appropriately conditioned air into the surrounding space, with no particularly harmful airborne particles. You will generally find them with a 900 watt power rating, but microwaves with 1100 watt are also an option.

With capacities ranging from 0.5 to more than 2 cubic feet, there is a model to fit kitchens of all shapes and sizes (see our guide here). They can also be placed on brackets or concealed under cabinet doors in some circumstances.

These also tend to be the cheapest microwaves you can buy - see see microwaves under 200 bucks and microwaves under 150 dolars - though there are premium options available at much higher prices.

countertop micorwave

A Look at Over the Range Microwaves

This is basically a microwave oven and a ducted range hood in one, dealing with all kinds of fumes and kitchen contaminants as it works. Over the range microwaves otherwise work in exactly the same way as a conventional microwave, with a variety of power levels (see here if 900 watt oven is powerfull enough), features, and settings. Their power and efficiency diminish with time, though, so this post on how to make them last longer will be invaluable to you. On another note, you would also do well to consult the troubleshooting guide if something goes wrong.

To get back to over the range microwaves, the venting system may include things like charcoal filters to help keep odors under control, keeping the air in the kitchen fresher and cleaner.

Although a more technically advanced gadget than a conventional microwave oven, it might be the most difficult and expensive to install.

black and silver microwave

Bottom Line…

As touched upon back at the beginning, there’s no ‘better or ‘worse’ choice where the various types of microwaves are concerned. The ventilation system your microwave uses will be determined by where you intend to locate it.

Building codes state specifically that an external venting system is essential for a range microwave, which also takes the place of a range hood. But if you plan on positioning your microwave anywhere else in the kitchen, you can go for something with a recirculating venting system and avoid additional installation costs.

Our Recommended Microwave Oven

  • It has ten power levels with multi-stage cooking
  • Ideal small-space solution
  • Easy-to-view interior lighting

About the author

Cornelia Suehr

A professional chef and a passionate writer on all topics related to cooking, baking, appliances and kitchenware. Her posts resonate with foodies, home chefs and professionals.


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