elements can be supplied for either total room heating or for intermediate heating during spring or fall. Reduced Operating Costs. Standard permanent split capacitor motors sustain... acoustical insulation provide quiet operation. Year-Round Comfort Control. An optional four-pipe system auxiliary hot water coil may be supplied to provide supplementary or between season... heating. Airtherm also provides a complete electric heating system with the advantages of four-pipe system flexibility and two-pipe system installation savings. Electric heating...