VAV-DH-B-10/20/30/40/50, Galvanized steel Construction. Voltage Rating: Single Phase / Three Phase VAV with Slip in Heater The reheat coils are factory fitted in to the corresponding VAV or CAV. It is designed so that the VAV or CAV followed by a heater battery are used in excessive humid places to avoid condensation of the equipment. Slip in heater-VAVs are widely used because it allows the duct work to be installed before the VAVs & heaters are available and simplifies the design. Furthermore, VAV with slip-in heaters may be installed without any special arrangements for their support.