HearthStone Aurora 8900 Series Owner's Manual page 9

Hearthstone Quality Home Heating Products, Inc
Using Vent Charts
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The location of the vent termination must meet the requirements of the current edition of ANSI Z223.1/NFPA
54, National Fuel Gas Code or CAN B419.1, Natural Gas and Propane Installation Code and the
requirements shown on page 15 of this manual.
Just as with any other vented device, vertical vent rise creates draft (negative pressure) in the firebox as the
exhaust gases heat up. If this draft becomes excessive, it can affect the performance or appearance of the fire.
The ORION 16 fireplace includes air and exhaust restrictors that are used to balance the draft in the fireplace to
the optimal level for installations where excessive draft might occur. The venting charts on pages 10 and 11
provide an easy means for determining whether your specific installation requires inlet air or exhaust restrictors
or both. To make the determination about whether air or exhaust restrictors are needed, a venting chart
worksheet is provided on page 12. Follow the instructions and fill in the worksheet for your particular
installation. This will allow you to determine the recommended restrictor settings for your exact installation.
Although this might appear to be a complicated process at first glance, it is really quite straight-forward and the
result will be a fire that looks and performs as intended. Several examples of worksheet calculations are shown
on page 13 to help guide you.
Please be sure to note that:
1. There are separate venting charts for Natural Gas and LP Gas. Refer to the appropriate chart for your fuel
type to determine your specific restrictor requirements. The settings in the charts have been determined
based on extensive testing.
2. Determine the total vertical vent rise and total horizontal vent run for your installation. All measurements are
made from the center of the vent opening in the back of the fireplace.
3. If your fireplace will not be venting directly though an outside wall to a horizontal termination or if more than
30" of horizontal vent run is required, some vertical vent rise will be required for the fireplace to function and
vent properly. Elbows will also be required for those installations. However, installations are limited to a
maximum of four 90° elbows (or 45° elbow equivalents).
4. Note: Two 45° elbows equal one 90° elbow.
5. The recommended restrictor settings in the venting charts allow up to two 90° elbows (or 45° elbow
equivalents) to be used without affecting the restrictor settings. Additional elbows will require that you
calculate a new equivalent horizontal run for your installation to account for the additional flow resistance
caused by the extra elbows. For the purposes of calculating the equivalent horizontal vent run, each
additional 90° elbow is equivalent to three feet of horizontal vent run. The total horizontal vent run including
elbow equivalents cannot exceed 10 feet.
6. The maximum vertical vent rise cannot exceed 20 feet.
7. There are two exhaust restrictors that are provided with your ORION 16 fireplace. They are labeled "A" and
"B". The A restrictor provides less exhaust restriction than B.
8. An air restrictor plate is also provided with your fireplace. It is a ring with bendable tabs that can be set to
adjust the amount of restriction in the air supply system. Once the appropriate number tabs are bent open
(in accordance with the requirements for your installation), the plate is inserted between the fireplace and
the vent starter pipe.
ORION 16 Series 8900
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