What is a Recirculating Microwave?

Coby McKinley Profile image

Written by:

Updated December 7, 2022

If you’re shopping for the best microwave, you may wonder what built-in ventilation system your unit will have. External ventilation is a common feature in range microwaves and the best built-in microwave of 2023 that sit above a kitchen stove, but what is a recirculating microwave? The typical countertop microwave vents internally or back into your kitchen.


  • Recirculating microwave ovens filter the exhaust from your cooking through a charcoal filter and back into your kitchen.
  • The charcoal filter sits underneath a stainless steel grease filter and clears some cooking odors from your home.
  • You should replace the charcoal filter in your recirculating microwave every 6-12 months.

This system is called recirculation, and it is the best choice when external venting isn’t available for your conventional microwave. So, if you need to know what a recirculating microwave means, read on for the necessary details.

What is a Recirculating Filter in a Microwave?

A recirculating microwave oven uses high-speed fans to filter microwave exhaust through a charcoal or grease filter. The filter sits in a stainless steel cavity on the microwave that you can remove to replace the filter regularly. While a recirculating filter isn’t as effective as other types of microwave venting, it still clears your kitchen of the most pungent cooking odors. In addition, countertop models usually have a recirculating vent, but some built-in microwaves share the same filtration.

Insider Tip

Your charcoal filter will lose effectiveness over time, so you should replace it every 6-12 months. Luckily, this type of filter replacement isn’t costly.

If you want an affordable microwave with an exhaust duct, consider learning what a microhood combination microwave is for an alternative vent type.

How Does a Recirculating Microwave Work?

Recirculating filtration is the simplest form of ventilation. It is preinstalled in most freestanding microwaves and requires minimal maintenance. In addition, you can activate a recirculating filter using the Auto-Fan button on your microwave control panel, and some models allow you to adjust the fan speed manually. Most recirculating microwaves use charcoal filters which are adequate but not as effective as external venting microwave exhaust.

Once you learn how to activate your recirculating fans, consider learning some more microwave tips such as how to use the defrost function on your microwave, remove scratches from the microwave’s back plastic, set the clock on a microwave, and prevent a microwave from interfering with the WiFi.

What Maintenance Tasks do Recirculating Microwaves Require?

Beyond replacing the charcoal filter, you should clean the grease filter regularly to ensure your fans are pulling the most air possible. You can clean the filter cover with soapy water and a rag. If there is built-up grease, you can use a brillo pad for a little more scrubbing power.


Do not block your stainless steel vent while the fan is spinning. You will not filter your kitchen air, and you may burn out the fan motor.


How to know if your microwave is recirculating or not?

If you’re wondering what is a recirculating vent on a microwave, it’s simple to figure out. First, turn on your microwave vent hood and feel for air on your face or hand. If you feel air coming back towards you, it isn’t an external vent microwave.

How does a ductless chimney work?

The cabinet range hood fans pull air through into the hood. The kitchen air moves through a charcoal filter, clearing food odors and steam from your cooking space.

How to replace your microwave charcoal filter?

Most microwave recirculating charcoal filters do not require tools to access the filter. You can remove the stainless steel grease filter by pressing the release clips. Ensure you have the correct size filter before sliding it in and replacing the grease filter.

STAT: A US Department of Energy survey found that 80% of OTR microwaves had external venting. (source)

Coby McKinley Profile image