My Rs thermostat has a range from 35 to 75 degrees. When set @ 35 when gone, the furnace ignites @ 55 and keeps it there. It doesn't need to be that warm, when gone. Can the low setting be adj & corrected to ignite at say 40 degrees? I see an adj screw the would adj the contact length. Is that how to adj it? In the plastic cover, molded in is #87006.