Direct Vent: Pipe Clearances 1
•7-3-1 Why are minimum clearances for
direct vent pipe important?
• Venting pipe can produce enough heat
to ignite combustibles
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Direct Vent: Pipe Clearances 1
•7-3-1 How are pipe clearances measured?
• From the pipe to the closest surface of
adjacent material
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Direct Vent: Pipe Clearances 1
What must be considered when
•7-3-1
measuring offset pipe clearances?
• Required slope
• Some manufacturers
have greater
clearances for
elbows
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Direct Vent: Pipe Clearances 1
•7-3-1 What materials are allowed in the
clearance space?
• Nothing but air
– Heat (without flame)
can ignite combustible
materials.
– Concealed
combustibles may
scorch or smolder
unnoticed before
catching fire.
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Direct Vent: Pipe Clearances 1
•7-3-1 Exercises
1. Mark on the elbow directly
above the fireplace the closest
possible point to the
combustible surface
x
above it.
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Direct Vent: Pipe Clearances 1
•7-3-1 Exercises
2. Mark the offset pipe connected to
the elbow on the point that is the
closest possible
distance from x
the combustible
surface above it.
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Direct Vent: Pipe Clearances 1
•7-3-1 Exercises
3. Which of the following would be acceptable if the
installation instructions state: “for vertical pipe, a
1" clearance to combustibles must be maintained.”
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Direct Vent: Pipe Clearances 1
•7-3-1 Exercises
4. Can noncombustible insulation be
allowed to be in contact with the vent?
– No
Why?
– Insulation transfers heat to combustibles
– Insulation blocks the cooling effect of
heated air rising and pulling in cooler air
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