Monessen Hearth DIRECT VENT MLDV500 - Manual (Page 13)

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MLDV Series Gas Fireplace VENTING INSTALLATION
INSTALLATION PLANNING
There are two basic types of direct-vent installation:
• Horizontal Termination
• Vertical Termination
It is important to select the proper length of vent pipe for
the type of termination you choose. It is also important
to note the wall thickness.
FOR HORIZONTAL TERMINATION
Select the amount of vertical rise desired. All horizontal run of venting must have 1/4" rise for every 1" of run
towards the termination below 7
1 /

feet of vertical rise. With 7 1 /

feet or more vertical rise off top of fireplace,
the horizontal run may run level. NEVER run vent piping downward.
You may use up to three 90° elbows in this vent configuration. Refer to Horizontal Termination Configura-
tions on Pages 17 and 18.
FOR VERTICAL TERMINATION
Measure the distance from the fireplace floor to the ceiling. Add the ceiling thickness, the vertical rise in an
attic or second story, and allow for sufficient vent height above the roof line.
NOTE: You may use two 45° elbows in place of a 90° elbow. You must follow rise to run ratios when using
45° elbows. The appliance is approved for use with three 90° elbows maximum or a combination of 90° and
45° elbows up to a maximum of 70°.
For two-story applications, firestops are required at each floor level. If an offset is needed in the attic, addi-
tional pipe and elbows will be required.
You may use a chase with a vent termination with exposed pipe on the exterior of the house. Refer to Install-
ing Vent System in a Chase below. If pipe is enclosed in chase, it is not exposed.
It is very important that the venting system maintain its balance between the combustion air intake and the
flue gas exhaust. Certain limitations apply to vent configurations and must be strictly followed.
INSTALLING A VENT SYSTEM IN AN OUTSIDE CHASE
A chase is a vertical boxlike structure built to enclose venting that runs along the outside of a building. A
chase is required for such venting.
NOTICE
When installing in a chase, you should insulate the chase as you would the
outside walls of your home. This is especially important in cold climates.
Insulation should be considered a combustible material. Maintain proper
clearances to all combustible materials.
W
ARNING
Always maintain minimum clearances around vent systems. The minimum clearance to
combustibles for horizontal vent pipe are 3” at the top and 1” at the sides and bottom
of the vent system until the pipe penetrates the nearest vertical wall (1” required). A
1” minimum clearance all around the pipe must be maintained at outside wall and on
vertical runs. Do not pack the open air spaces with insulation or other materials. This
could cause high temperatures and may present a fire hazard.
*Unless the vertical run is 7Z\x feet or higher (top vent units only), the clearances for the
horizontal run is 1” at the top.
Never run the vent pipe down. This may cause
excessive temperatures which could cause a
fire.
W
ARNING
Treatment of firestops and construction of the chase may vary from
building type to building type. These instructions are not substitutes for
the requirements of local building codes. You must follow all local building
codes.
W
ARNING