I have this Furnace where I rent the house, but I think its consuming too much gas. The original was Natural gas but change to Propane. I have 3 zones, 2 bedrooms: one with temp to 66 from Programmable Thermostat Honeywell, master bed room + living room: one same thermostat and temp, Basement: one same thermostat but most the time off. In summer for 3 months I have 170 Gal. of propane and now on Winter 40 days 170 Gal. I have fire place and it’s on most the time to save $, the furnace goes on at night only when temp drop below 66. Is that normal to burn this much gas in 40 days. I have Gas stove, gas dryer and gas hot water. What can I do to have this furnace saving $ please? Should I have change parts or what? Thank You