Hi stevenjackson,
Welcome to the Heartland Owners Forum. I see you have been a member for a while and maybe just looking. I have also looked at the pictures of the 3100ES and specs. It does not list a microwave that I can find. Hopefully someone from the factory will chime in soon and let us know for sure.
I have seen some stoves with the microwave taking place of the oven, below the burners, and this may be an option for you. You and your dealer might work out a trade up.
Enjoy the forum.
Jim M