If you want to use model W10294730 in the re-circulating model you will need to purchase Charcoal Filter Kit Number W10294730.

Whirlpools gas cook top model SC8720EDB is a downdraft system. The vent system is installed in the cabinet below. It can go into the back wall or straight down through the floor. You can go on the Whirlpool website to bring up this model to download the installation instructions.
Venting system must terminate to the outside. Do Not terminate the vent system in an attic or other enclosed space.

This cook top can be used with Propane gas. There are directions in the installation instructions on how to convert to L.P. Gas conversions (from Natural gas to L.P. gas; or from L.P. gas to Natural gas) must be done by a qualified installer.

A 120-volt, 60-Hz, AC-only, 15- or 20-ampere, fused electrical supply is required. A time delay fuse or circuit breaker is recommended. It is recommended that a separate circuit serving only this appliance be provided. Electronic ignition systems operate within wide voltage limits, but proper ground and polarity are necessary. In addition to checking that the outlet provides 120-volt power and is correctly grounded, the outlet must be checked by a qualified electrician to see if it is wired with correct polarity.

Important: This cooktop is equipped with an electronic ignition system that will not operate if plugged into an outlet that is not properly polarized.

You would add a small amount to the steam basket with your vegetable or whatever you are steaming and then follow the directions of the microwaves as to how long to cook them.