Honeywell DH90A1007 Installation Guide - Page 6

DH90 Dehumidifier • For HVAC Installer Only Fresh air intake EARD6 Motorized damper W8150 Controller Heating & A/C unit Supply air Indoor air return Indoor air supply Indoor air return Figure 3: Attic Installation. Instead of installing a separate return to the DH90, The preferred method of installation is to create a and if the existing system has multiple returns, Attic inssetaplalartaitoen return for the DH90 in a central area of it is possible to select one to disconnect from the structure. Duct the supply of the DH90 to the the existing forced air system and use it for the air supply of the existing HVAC system. Connect dedicated DH90 return. Always select a return from an insulated duct from outside to the 6" collar of a central location in the structure in an area that is the DH90 if you wish to provide fresh air. Adjust a always open to the rest of the structure. Do not use damper in the duct to provide the desired amount a return from a room that may have its door closed of fresh air. See Figure 3. much of the time. 4.4D Installation in an Attic with an Existing Forced Air HVAC System Important: ALWAYS install a catch pan with a drain or float interrupt for condensate under the DH90 in an attic or condensate may damage the living space below. The interrupt switch should be installed in series with the field wire that connects the blue lead from the DH90 to the dehumidistat. If overflow occurs, this switch opens the compressor control circuit and stops water production before the catch pan overflows. The DH90 will continue to ventilate or circulate air as normal, but will not dehumidify until this switch closes. 4.4E Installation in a Structure with No Existing Forced Air HVAC System When installing the DH90 in a structure that does not have a forced air HVAC system, a single return for the DH90 should be installed in central open area of the structure. DO NOT locate the return in a bathroom or a kitchen. The supplies of the DH90 should be located in the remote areas of the structure (such as bedrooms, den, etc.). By ducting this way, the air inside the structure will circulate through the DH90 to be filtered and dehumidified. 6" diameter duct is recommended for branches to the bedrooms, 8" diameter duct is recommended for branches to larger areas. Connect an insulated duct from outside to the 6" collar of the DH90 if you wish to provide ventilation. See Figure 4.