DuraVent DuraTech 5”-8”- Square Ceiling Support Box w/ Collar

Planning Your Installation

The following recommendations are general guideline to assist in the layout and selection of the chimney components needed for your installation. Always follow Duravent Installation instructions before installing your chimney system., found with the cap or support box.

• • The diameter of the chimney should match the outlet size of the appliance. An improperly sized chimney results in poor draft and excessive creosote formation.
  • Measure the diameter of the appliance flue outlet. Select the chimney and either DVL or DuraBlack connector stovepipe with the same size diameter as the appliance flue outlet. For fireplace installations, refer to the sizing chart in the back of this catalog.
  • Determine if the installation is a through-the-roof installation or a through-the-wall installation. A through-the-wall installation will require additional components (Wall Thimble, Tee/ Cap, Tee Support, and Wall Straps).
  • Install the chimney in the interior of the structure whenever possible. A cold exterior chimney will produce less draft and will generate more creosote.
  • If possible avoid offsets that serve to restrict the natural draft. A straight vertical installation is more efficient and less likely to develop creosote. If an offset is required to avoid rafters or other obstructions, measure the horizontal distance required and the vertical height available. Both 15° and 30° elbows are available. Elbows have a 360° swivel base to allow orientation of elbow direction only. Elbows are fixed at 15° or 30°. Elbows greater than 30° are not allowed in the United States. A maximum of two offsets in a single installation are permitted. Refer to the offset table in the back section of this catalog. At least one Elbow Strap is required for each offset. Elbow Straps ensure adequate support.
  • Determine the minimum chimney height above the roof line. Building codes require a minimum of 3′ above the roof penetration and at least 2′ higher than any portion of a building within 10′. See figure 1. The termination cap is installed above that point. If chimney extends 5′ or more above the roof penetration an extended roof bracket is required. An additional roof bracket is needed every 5′.
  • Measure the roof pitch. For example a 6/12 pitch has a vertical rise of 6″ over a horizontal distance of 12″. Select the appropriate flashing.
  • Determine the total length of chimney and stovepipe required for the installation. To calculate the installed per length of 5″-8″ DuraTech pipe, subtract 1 ¼” per joint. For 10″-24″ diameter, subtract ¾” per joint of pipe. Subtract 1 ¼” per joint of DuraBlack stovepipe. Subtract 1 ½” per joint of DVL stovepipe. Minimum chimney height, at sea level, of straight vertical chimney is 10′ to 15′ above the appliance outlet. Higher elevations, or the use of elbows or a tee, will require approximately 30% to 60% more height to provide for an adequate draft.
  • For a UL approved shroud, see the DuraTech Shrouds Installation Instructions (L157). View online at www.duravent.com, under catalogs and instructions.
  • Be fire safe. Maintain at least 2″ clearance to combustibles. Follow local building codes and have your chimney inspected by a certified professional.