(FIG. 8) MULTIPLE UNIT BAROMETRIC
DAMPER INSTALLATION
For this type of installation, it is best to use a draft control for each water heater located on the riser between the vent outlet and the breeching - Location “A”. When this riser is too short to permit the installation of a draft control, locate a separate control for each water heater on the main breeching as illustrated in Location “B”. If, because of general crowding or other reasons, neither of these locations are possible, use a single large control in the breeching between the water heater nearest the chimney and the chimney, as shown in Location “C”.
All draft readings are made while unit is in stable operation (approximately 5 minutes running time).
Masonry Chimney
A masonry chimney must be properly sized for the installation of a high efficiency gas fired appliance. Exterior masonry chimneys, with one or more sides exposed to cold outdoor temperatures, are more likely to have venting problems. The temperature of the flue products from a high efficiency appliance may not be able to sufficiently heat the masonry structure of the chimney to generate proper draft. This will result in
condensing of flue products, damage of the masonry flue/tile, insufficient draft and possible spillage of flue products into an occupied living space.
Carefully inspect all chimney systems during the project design phase. If there is any doubt about the sizing or condition of a masonry chimney, it is prudent to reline the chimney with a properly sized and approved chimney liner system. Metallic liner systems (Type “B” doublewall or flexible or rigid metallic liners) are recommended. Consult with local code officials to determine code requirements or the advisability of using or relining a masonry chimney.
OUTDOOR INSTALLATION
(FIG. 9) OUTDOOR VENTING
Units are self venting and can be used outdoors when installed with the optional Outdoor Cap. This cap mounts directly to the top of the water heater and covers the flue outlet and combustion air inlet openings on the jacket. No additional vent piping is required. Maintain a minimum clearance of 3” (76mm) to combustible surfaces and a minimum of 3” (76 mm) clearance to the air inlet.
NOTE: Common venting systems may be too large when an existing unit is removed. Be careful to resize any common venting system when new appliances are installed or existing appliances are replaced.
NOTE:
Flue gases will form a white plume in winter. Plume could obstruct window view. Flue gas condensate can freeze on exterior surfaces or on the vent cap. Flue gas condensate can cause discoloration of exterior building surfaces. Adjacent brick or masonry surfaces should be protected with a rust resistant sheet metal plate.
NOTE: Venting of a high efficiency appliance into a cold or oversized masonry chimney can result in operational and safety problems.
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