Installation instructions
Fig. 10 Mounting the heater
3.5Combustion air requirements
Warning: In areas where freezing temperatures are common the twin pipe system is recommended. In a single pipe installation, a negative air condition may result in cold air being drawn across the heat exchanger coil causing it to freeze and burst. This failure is not covered under the manufacturer’s warranty.
Warning: When installed in an environment where corrosive chemicals or dirty air are present the twin pipe system is required.
Twin pipe
The
The maximum length of the combustion air inlet is 39 feet with one elbow. Subtract 6 feet for each additional elbow. Maximum number of elbows permitted is 4.
Single pipe
Although it is permissible to draw combustion air from inside the structure, it is not the manufacturer’s recom- mended installation method. Always install a 3 inch elbow on the combustion air inlet to prevent foreign objects from falling into the unit (see Fig. 11).
Fig. 11
If a single pipe installation is performed. Use the follow- ing guidelines when providing adequate combustion air for the recirculating water heater as well as any other appliances that may consume air in the space. Always follow local codes if more stringent.
•Appliances located in unconfined spaces:
–a) An unconfined space is one whose volume is greater than 50 cubic feet (1.42 cubic meter) per 1000 Btu per hour (292.81 watts) of the combined rating of all appliances installed in the space. That would be 6200 cubic feet (175.6 cubic meter) of air required for the
–b) In unconfined spaces in buildings of conventional frame, masonry, or metal construction, infiltration air is normally adequate to provide air for combustion.
–c) Installations in structures that have been tightly constructed (air infiltration rate of 0.40 ACH or less) must provide combustion air per the National Fuel Gas Code. Consult an HVAC specialist if your air infiltration rate is questionable. For these types of installations, the twin pipe system must be used.
6 720 607 909 | 11 |