I have a 7 year old Carrier 10 SEER split System Heat Pump, Model 38YCC. I asked the local Carrier Installer whether it is a single stage or multi-stage unit, so I can buy a new programmable thermostat appropriate for my unit.
The Carrier installer rep I spoke with said it's a multi-stage unit, but I question whether the unit is multi-stage.
The unit has only one compressor. I don't how many strip heaters are in the air handler.
Can anyone help me? Thanks

Yep just buy a 2 stage thermostat. The reason is the heat pump is one stage and the electric heaters in the inside air handler is the second stage.