Thermador PH48HS Ventilation Guide - Page 6

SELECTING the right hood CHOOSING THE RIGHT CFM 1. POWER and size of the cooktop The power of your cooktop, measured in BTUs (British thermal units), is perhaps the most important factor in determining CFM (cubic feet per minute) needs for your hood. Professional Series RANGES AND RANGEtops Thermador's Professional Series Hoods are tested and approved to withstand the high heat generated by our Professional Ranges and Rangetops. Professional gas cooktops generally should have 1 CFM for every 100 BTUs. Masterpiece® Series Cooktops Thermador's Masterpiece Series Hoods are best matched with our non-professional cooking products. For electric and induction cooktops, and gas cooktops under 60,000 BTUs, choose a blower with a minimum of 100 CFM per 12" of cooktop width. Example: A Thermador 30" Professional Range with a 60,000 BTU Cooktop should have a 600 CFM Hood. It is also important to note that this method assumes that all burners are on high at the same time. Griddles and grills generally require an additional 200 CFM. 30" PROFESSIONAL WALL HOOD (600 CFM) Example: A Thermador 36" wide Cooktop requires a blower with a minimum of 300 CFM. 36" HOOD WITH >_300 CFM + 30" PRO GRAND RANGE (60,000 BTU) + 36" INDUCTION COOKTOP CHOOSING THE RIGHT CFM 2. Cooking style The appropriate airflow capacity is determined by evaluating the cooking space and the occupants' cooking habits. • More demanding cooks usually require more exhaust capacity to handle moisture generated by boiling large pots of water or the grease and smoke resulting from grilling or frying. This cooking style could require a hood or downdraft system with airflow of 600 to 1300 CFM. • High heat cooking or aromatic foods may require additional CFM. Increasing capture area by 3" on each side is also a recommended way to address this issue. • For those who are used to preparing quick meals in a relatively small kitchen, a hood with 400 to 600 CFM may be adequate ventilation for the cooking space. • If the cooking surface is in a peninsula or island, a larger capacity hood can provide better capture when there are cross currents and when the hood needs to be mounted higher. Downdraft ventilation systems are also a good alternative. 3. Length and size of duct work Proper performance is dependent upon proper ducting. Use a qualified and trained installer. • Do not use flexible duct; it creates back pressure/air turbulence and reduces performance. • Straight runs and gradual turns are best. Use the shortest route with the fewest turns possible. • Check local codes for makeup air requirements, if any. For more information on makeup air, see page 42. If using a 10" duct, Thermador recommends not exceeding 150 feet of duct. Transitions, elbows and wall or roof caps are all factors that will add more static pressure, therefore increasing your equivalent duct run. Example: Assume you have 30 feet of straight 10" duct with two 90-degree elbows and an outside wall cap. To calculate the equivalent straight duct run pressure, you would add 12 feet for each elbow, and 5 feet for the outside wall cap, increasing your equivalent total run from 30 to 59 feet. Duct Static Pressure equivalents 30' DUCT with 2 elbows and an outside wall cap = 59' of straight ducting­ For more information on the equivalent duct lengths for commonly used transitions, see page 41. 8 9