I represent ASA Electronics, the producer of the JENSEN brand of televisions, stereos, and speakers, the Voyager brand of observation monitors and cameras and Advent appliances. At ASA, we strive to provide excellent customer service and product satisfaction and would like to offer some assistance in this matter.
The Advent Digital Thermostats will go down to 60°F. If you have a LP furnace and are able to locate a suitable thermostat that goes lower than 60° F, you may be able to install that to control your LP furnace directly, separate from the AC unit.
Please let me know if you need any further assistance.
ASA Electronics - JENSEN, Voyager, iN-Command & Advent Tech Support Team