00494pamaa2200169 4500 0000014382 20060814090000.0 0071134689 697 LEV TP7466.5 LEV 1993 LEVENHAGEN HVAC controls and systems John I. Levenhagen and Donald H. Spethmann. New York: McGraw Hill, 1993. xiii, 334p.: 23cm. Heating -- Control Air conditioning -- Control spethmann, Donald H.