pixelknave wrote:We have three Fujitsu Halcyon units in our house…two ceiling units, and one concealed duct unit. ...I've been searching for a way to control these via the same centralized thermostat that controls our radiant heat (in our case, an Ecobee 3)....
For a somewhat different approach, take a look at
https://www.intesishome.com (then click
Discover your WiFi SmartAC). They make two types of units:
Brand Specific and
Universal. The type names are a little misleading. The brand specific is designed to connect internally into the A/C unit's control circuitry, while the Universal "connects" via IR. Both the Brand Specific and Universal types are actually specifically programmed for whatever type of A/C unit you have.
At this time there is no direct access to the local unit, they are only controllable through the Intestshome web site:
https://user.intesishome.com/login (click
View an example). An API is available, but only for commercial applications. They say a user level API is in the works. Though, someone with enough interest and time could probably figure a way to control the web interface via curl. Finding a reseller is difficult, but if you push a little, they will sell direct.
As-is, this will not solve your problem. But, if they deliver the promised user API, then you could use Indigo to interconnect a smart thermostat with the A/C unit.