I've done this before twice. Each of them differently. One time was on a 4 zone Honeywell zone board with 8 thermostats hooked up to it. I simply used a toggle switch to go back and forth to where the load would be. It was on an engineer's house and he wanted to switch the thermostat back and forth depending on the season. The other time, I bought 2 wireless thermostats with one receiving station. Whichever thermostat was adjusted last had control of the system. So as long as you don't change the upstairs then the downstairs 10 minutes later, you were fine. It still had the 5 minute waiting period, so you couldn't short cycle it. Its application was the guy had an office he used during the day and wanted it set for his comfort and he rented an apt. out beside him on the same system and when the guy that lived there got home at night, he wanted control and neither one of them wanted the other guy going into their space to control temp while the other one wasn't there. Or you could just buy a zone board and don't put any dampers on it.
I believe it was a 3 way toggle switch from Radio Shack. It was about 5 years ago, it gives me a headache to think about it and what a pain in the arse it was to do. Everytime I go to the guys house for service and I see this beast, it makes me shudder and I hope it never breaks, it will take me an hour of staring at it to remember how everything works.
We do a fair amount of strange and off the wall sort of stuff. Lots of high end customers with somewhat odd needs. It's my job to figure out how to make it all work. We've gotten a few calls from customers who have called another company out for service and it confused the hell out of the other tech. Pretty much guaranteed us a customer for life as well as referrals. It makes the job more interesting.
I don't think the Infinity can have averaging remotes, but I could be wrong.
On stats that can have averaging remote sensors.
As its name implies, the stat will use the average of the tempertures sensed.
So if you have 2 sensors upstairs, and 2 downstairs.
The stat set for 73°F cooling. If the sensors upstairs are sensing 76, and the sensors downstairs are sensing 72. The average would be 74, so the stat would bring on the A/C.
It seems like the remote sensor and using average is the least painful solution. The only issue is that the differential between up and down varies and finding the right setpoint will be the challenge.
I'm also interested in the switching option, but I'm concerned that option will confuse the IAQ's and EIM. Or are all the brains in the EIM and it wouldn't know the difference switching between 2 tstats?
Its not zoning period.
He could also get Honeywells wireless.
I believe its the W8635
The Logic, is in the stat.
being that the 16i uses 80% fan speed for low speed does create a challenge when zoning
when the smallest zone in the house is the only zone calling, 1 solution is a dump zone
which wastes all kinds of energy!
there are a few other tricks to get the fan speed down lower for that situation
but you will have to think outside the box
i have had private discussions with distinguished members of this website about (16i and fan speed)
and the solution gets complicated, but your correct in saying it's doable