Folks...to all of you that have educated me about the issues in zoning a Trane xl16i A/C.thanks.

The major issue has been that the system does not adjust fan speed depending on which zone(s) are calling for air, nor does the system adjust fan speed based on temp v. set point. Our house is not identical by floor...the downstairs is about 1150 sq ft and the upstairs about 850. we are in NJ

Well, after much nagging and a few calls to the Trane corp office, I finally got an offer of help from my installer...he proposed one of these 4 choices and if ya'll could tell me what you think, I would appreciate it VERY much.

The options from the installer.
(1) we can install the Trane zoning system at no cost to you and see if it makes any difference.
(2) we can upgrade your system to a 19i which Trane says will work. I will supply labor the only thing you would cover is the difference in cost of the condensing unit.
(3) Third we can convert you system back to a single zone and refund you the cost of the zone control package.
(4) Fourth we can get you a price for installing a second air handler and condensing unit for the second floor. The ductwork is already there it would be the equipment and electrical work.

So...what do you recommend and why?

My guess is that another A/h and condenser would be best (#4), but I'm sure the most expensive, probably prohibitively so, as such this is probably not a realistic option unless it is the only way to go. Plus, we already have a 4 ton unit..what else can they add?

If the 19i works properly controlling fan speed, for under 1k, I might get the best solution.

Can the 19i do a better job of controlling fan speed than the 16i? why? Do I need pressure sensor rather than a bypass damper, or both? How important is the Tstat if I choose the 19i? If it matters, which one do i get?

Anyone know if the new trane zoning solution works for the 16i? this would be cheapest, but if it doesn't work, what good is it.

Guys--please write as much as you can, what you recommend and why...also, please and let me know what i need to ask the installer...

Thanks VERY VERY much for your help.