INSTALLATION : COMBUSTION AIR INLET
ADDITIONAL AIR INLET FOR MAKEUP AIR IN A RELATIVELY “ AIRTIGHT ” BUILDING (INCLUDES MULTIPLE UNIT INSTALLATION) When the GARN® unit (or multiple units) is installed in a relatively “ airtight ” building, a makeup air duct is required. Such a structure is usually newer construction with an air barrier that has been installed with attention to detail, seams have been caulked, and windows and doors have good weather stripping. Air makeup must be provided to the room because when the GARN unit’s combustion chamber door is open ed during firing, air is being drawn from the room into the combustion chamber and out through the flue. Drawing air from inside depressurizes the room. When there are other combustion appliances in the same structure, such a condition could backdraft the other appliances.
INSTALL A MAKEUP AIR DUCT IF THE GARN UNIT IS INSTALLED IN A STRUCTURE WITH OTHER COMBUSTION APPLIANCES. Otherwise, backdrafting of the other appliance make
occur, and a hazardous condition will result.
Using an additional air inlet hood, install the air makeup duct penetration as low as possible in the wall (while still avoiding possible snow drifts, obstructions, etc). Installing at the same height as the combustion air inlet hood of the GARN unit is acceptable. Route the air makeup duct inside the building, turn the duct towards the ceiling, and route a vertical section of duct until it terminates within 12 inches of the ceiling. The reason for installing a tall, vertical section of duct inside the structure is to create an effective air lock. The air lock will ensure that cold air is not entering the room at all times; only when the combustion door is open. An air makeup duct is acceptable for single or multiple unit installations in the same building. Insulate all of the air makeup ductwork. See the diagram below:
GARN WHS 1000 and WHS 2000 Manual © HY-C Company LLC - September 2024
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