Thermostat issue- Previously diagnosed bad batteries on thermostat. Batteries keep failing in a short amount of time. System did not have a common. Replaced thermostat with new Pro1. System was missing filter door. Replaced 14x25x1 filter and fabricated new filter door. Inducer motor has high amp draw. Blower wheel is dirty and blower capacitor is weak. Supply and return plenum are duct board and supply plenum is not correct size for equipment. Recommend replacing both with metal plenums. System lacks proper flood protection. Tested thermostat. System operating at this time.