How can I tell what kind of heating system I have?
Rheem's Digital Programmable Thermostat Model# RHC-TST411MDMS. This Thermostat is Required for Enhanced Modulating Features.
Check this site to determine the exact model and specs.(PDF file) http://www.expresshvac.com/res_components/gas_furnace/hvac_rheem.asp
Most of these Rheem furnaces are gas fired, forced hot air.