Range vent problems
I live in Houston, TX in a two-story townhouse. Kitchen is in the middle of a shared wall. Range is a circa-1982 slide-in Jenn-Air electric downdraft model that needs to be replaced. I currently have an over-the-stove microwave with a fan built in, but there's no ducting for it to connect to so it recirculates into the kitchen.
The range's downdraft fan never performed great (the run is ~15 feet, and I think it's 7" ducting), but it was better than nothing. I'd hate to rely on just the microwave's recirculating fan!
Problem is, only Jenn-Air makes a 30" downdraft range anymore, and I can't find anyone who'll say anything good about the modern / current Jenn-Airs, so I'm reluctant to spend ~$2K on one.
I have some questions:
1) Per local Houston building code, can I install an electric range without a functional outdoor vent?
2) Would it be a huge mistake to install a range with no outside ventilation capability (if I went with a non-JennAir, thus non-downdraft model)?
3) Is there a reasonable and effective way to tie the microwave vent into the downdraft ducting?
4) How hard would it be to have an effective upward vent system retrofitted into my place? Range is against a common wall with my neighbors. Wall is a firewall and extends all the way to roof...would require a ~30' run straight up. (Does code even allow vents to run in common walls / firewalls?)
4A) My kitchen is very small and I need to keep the microwave over the range. If I added a new vent, I'm guessing it's impractical to expect the microwave's built-in fan to adequately drive a 30' vent. Should I expect to need an inline fan to supplement the microwave's fan?
5) If I choose to have a new vent run, who should I engage to do the work (i.e., general contractor, plumber, HVAC contractor, etc.?)