Thermador VCIN36JP Installation Instructions - Page 9
Ductwork Preparation
View all Thermador VCIN36JP manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 9 highlights
Ductwork Preparation Ducting Recommendations Proper performance is dependent upon proper ducting. Local building codes may require the use of make-up air systems when using ducted ventilation systems greater than speci¿ed cubic feet per minute (CFM) of air movement. The speci¿ed CFM varies from locale to locale. It is the responsibility of the owner and the installer to determine if additional requirements and/or standards apply to specific installations. DO NOT USE FLEXIBLE DUCT; it creates back pressure/ air turbulence and reduces performance. Always use metal ductwork with a minimum diameter of 6" (150 mm). Always install a metal vent cover where the ductwork exits the house. COLD WEATHER installations should have an additional backdraft damper installed to minimize backward cold air flow and a nonmetallic thermal break to minimize conduction of outside temperatures as part of the ductwork. The damper should be on the cold air side of the thermal break. The break should be as close as possible to where the ducting enters the heated portion of the house. MAKE-UP AIR: Local building codes may require the use of make-up air systems when using ducted ventilation systems greater than specified CFM of air movement. The specified CFM varies from locale to locale. It is the responsibility of the owner and the installer to determine if additional requirements and/or standards apply to specific installations. For safety reasons, ducting should vent directly outdoors (not into an attic, underneath the house, into the garage or into any enclosed space). The unit cannot be used in conjunction with a recirculation unit. If using a 10" (254 mm) duct, THERMADOR® recommends not exceeding 150 ft (46 m) of duct. Keep duct runs as short and straight as possible. Elbows and transitions fittings reduce air flow efficiency. Back to back elbows and "S" turns give very poor delivery and are not recommended. A short straight length of duct at the inlet of a remote blower gives the best delivery. Hoods are supplied with a 10" (254 mm) round transition. A locally supplied transition is required for other sizes. Transitions, elbows and wall or roof caps are all factors that will add more static pressure, therefore increasing your equivalent duct run. For example, assume you have 30 ft (9.2 m) of straight 10" (254 mm) duct with two 90° elbows and an outside wall cap. To calculate the equivalent straight duct run pressure, you would add 12 ft (12.7 m) for each elbow, and 5 ft (1.5 m) for the outside wall cap, increasing your equivalent total run from 30 to 59 ft (9.1 to 17.9 m). Use Table 4 on page 8 to compute permissible lengths for duct runs to outdoors. NOTE: Do not exceed maximum permissible equivalent lengths. English 7