When installing ICP communicating equipment, it is possible to use non-comm thermostats with these systems. The control boards of both the indoor and outdoor sections will have terminal strips for "Legacy" connections (standard 24v wiring). Also on the control boards, you will see a plug in style connection with Dx+, Dx-, R, C.  If you are going to install with a non-comm thermostat, you will NOT use the plug in connector, just the standard low voltage terminal strip with R, C, Y. Damage may occur if you use a non-comm thermostat on the DX+, DX- connections. 

See the links below for wiring examples. 

Standard non-comm 2 wire connection

Non-comm 2-stage wiring connection

 Non-comm 2-stage heat-pump wiring

Non-comm 3 wire connection