sides of conditioning heating unit 100 primary coils 108 a 108 b may circulate chilled water synthetic coolant e g freon hot water or steam a bypass damper 109 on the right side of air conditioning heating unit 100 allows return air to bypass coils 108 a and 108 b bypass damper 109 is associated with an additional filter on the right side of air conditioning heating unit 100 in alternate embodiments coils 108 a 108 b may be stacked on a single side of air conditioning heating unit 100 during cooling operation air conditioning heating unit 100 pulls return air flow through the space between floor 101 a and internal ceiling 104 some of the return air typically at approximately 75 degrees fahrenheit passes across coils 108 a 108 and is cooled to typically about 50 degrees fahrenheit the rest of the return air flows directly through bypass damper 109 without additional cooling the cooled air flowing across coils 108 a 108 b and the air flowing through bypass damper 109 is mixed with the outside air provided through conduit 105 which typically has been cooled to approximately 55 degrees fahrenheit the resulting discharge air is typically at approximately 60 to 65 degrees fahrenheit air conditioning heating unit 100 then discharges the cooled and filtered air into the space between concrete slab 101 b and raised floor 103 the discharge air.