HCA supports the X10 thermostats available from Residential Control Systems (RCS).  Both the Bi-Directional and Uni-Directional models are supported.  The Bi-Directional thermostat contains protocols that, if enabled, ensure that signals sent by HCA are acted upon.

While a Bi-Directional thermostat HCA can retrieve the various settings of the thermostat (setpoint, economy or setback,  fan, etc) and, using a HCA program, make decisions based upon the data retrieved.

If you are worried about using X10 in a critical application like HVAC - don't!   The RCS Bi-Directional thermostat contains several communication modes that use X10 signals to send and confirm that the command you sent was what was received by the thermostat.  HCA fully supports these command protocols and will retry commands that didn't appear to be received by the thermostat correctly.

More information on the RCS line of thermostats can be found here.

How HCA uses thermostats is described in the HCA User Guide Thermostat Appendix .