FIGURE 8
FLAT ROOFTOP INSTALLATION, ATTIC OR DROP CEILING DISTRIBUTING SYSTEM. MOUNTED ON
ROOFCURB. CURB MUST BE LEVEL.
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Place the unit as close to the conditioned space as possible allowing clearances as indi- cated. Run ducts as directly as possible to supply and return outlets. Use of
On ductwork exposed to outside temperature and humidity, use a minimum of 2″ of insulation and a vapor barrier. Distribution system in attic, furred space or crawl space should be insulated with at least 2″ of insulation. 1⁄2″ to 1″ thick insulation is usually suffi- cient for ductwork inside the air conditioned space.
Provide balancing dampers for each branch duct in the supply system. Properly support ductwork from the structure.
IMPORTANT: In the event that the return air ducts must be run through an “unconfined” space containing other fuel burning equipment, it is imperative that the user/homeowner must be informed against future changes in construction which might change this to a “confined space.” Also, caution the user/homeowner against any future installation of additional equipment (such as power ventilators, clothes dryers, etc., within the existing unconfined and/or confined space which might create a negative pressure within the vicinity of other solid, liquid, or gas fueled appliances.
H. RETURN AIR
!WARNING
NEVER ALLOW PRODUCTS OF COMBUSTION OR THE FLUE PRODUCTS TO
ENTER THE RETURN AIR DUCTWORK, OR THE CIRCULATING AIR SUPPLY.
ALL RETURN DUCTWORK MUST BE ADEQUATELY SEALED AND SECURED
TO THE FURNACE WITH SHEET METAL SCREWS, AND JOINTS TAPED. ALL
OTHER DUCT JOINTS MUST BE SECURED WITH APPROVED CONNECTIONS
AND SEALED AIRTIGHT.
FAILURE TO PREVENT PRODUCTS OF COMBUSTION FROM BEING CIRCU-
LATED INTO THE LIVING SPACE CAN CREATE POTENTIALLY HAZARDOUS
CONDITIONS, INCLUDING CARBON MONOXIDE POISONING THAT COULD
RESULT IN PERSONAL INJURY OR DEATH.
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