I have a Wi-Fi thermostat and love it. Mine does run on 4 AA batteries so I cannot offer any electrical advice. Talk about being spoiled. If I'm a little chilly upstairs I just go on my IPhone and up the temp a degree or 2.

Mine was included with my security system package as I can operate the whole system from 1 app. It also has its own router that connects to my internet modem and I'm locked out of that router. Only the company can remote into it and make changes.

If you have to buy 3, that cost will add up. Call me old fashioned, but they're not a necessity, just complete luxury and convenience. My batteries last along time. I change them twice a year. I get 4 top of the line brand AA batteries just to be safe.

It is hard to say how difficult it would be to run wiring to your three thermostats. My suggestion is to hire a good electrician with the proper tools to snake the new wiring. An HVAC contractor can then install the new thermostats and make the new wiring connections.

Normally, power for thermostats comes from the furnace, not the AC house wiring. So your current thermostat wiring may be sufficient.

The biggest issue when installing a WiFi thermostat is the lack of the ground wire and the not the power (24V) wire. In some cases there may be a spare wire unused wire in the cable bundle. If that is the case then it might be an easy fix.

I also have a question for Flame. On a Bryant Evolution system, would you suggest using the Nest thermostat?

FWIW--husband installed three non-wifi thermostats and they work great. We an hear the "click" when the AC comes on or off but our house is staying much more evenly regulated for temps...I think we had issue for long time with the original thermostats NOT working the compressor w/fan correctly.

Ecobee 3 is a great wifi t-stat. I really like the wireless temperature probes it comes with when it comes to regulating temps. So you can always stick one of the wireless temp sensors in that room that you're not comfortable in and the system will factor in the temperature of that specific room instead of just the temperature reading on the thermostat.

But Nest sucks.. Not only have they been hacked and bricked and left thousands of people without heat during the winter because of security reasons.. But, I just don't agree with the "learn when im home" feature and I have taken many out because of it, especially in homes with several floors where different floors are being visited at different times and it's just a dumb thermostat not a smart thermostat.. I've just had many people not satisfied with nest..