FLUES
General (Gravity)
- Flues shall be
min. 5 ft. height from the collar (excluding BW vent). UMC 806.2.
- Wall furnace, BW
flues shall terminate min. 12 ft. above the furnace base. UMC 806.3.
- Bends: May have
45° max., except one can be 60°. UMC 805.1.
- Size: Min. 7 sq.
inches. UMC 808.
- Solid & gas/oil
fuel are not allowed in the same vent. UMC 802.4.
Connector
- No single wall
in unoccupied or concealed space or attic. UMC 815.1.
- Horizontal-to-
vertical less than 75% of total run single wall (horizontal is <45°).
UMC 815.2.2.7.
- Horizontal- to-
vertical less than 100% of total run double wall (horizontal is <45°).
UMC 815.2.2.7.
- Slope 1/4"
per ft. toward the appliance. UMC 815.2.2.4.
- Three sheet-metal
screws connector to collar. 815.1.
- Three sheet-metal
screws single wall to double wall. 815.1.
Vents (Multiple Appliances)
- All must enter
on the same floor. UMC 809.1.
- Connectors staggered
where they enter. 809.2.
- Flue must equal
largest connector plus 50% of others. 809.3.
- Connector to highest
point possible.809.4.
Termination
- B Vent: Min. 2
ft. above and located at least 8 ft. from a vertical surface. UMC 806.4.
- Min. 1 ft. above
the flat roof. (slope: <6-in-12).
- Air intakes (makeup
air): 3 ft. above or 10 ft. away. UMC 806.6.1.
- Windows/doors:
Min. 4 ft. below or 4 ft. horizontal nor <1ft. above. UMC 806.6.
- Minimum 4 ft. from
property line. UMC 806.6.
Forced
or Induced Draft
- Positive-pressure
systems shall be gas-tight. UMC 816.2.
- Interlock burner
and blower (dampers). 816.1.
- Outlet less than
12" from combustion-air intake. 816.5.
- Min. 7 ft. above
grade. UMC 816.5.
- Termination: 12"
from openings & 2 ft. above adjoining building. UMC 816.5.
Gas Vent Entering Masonry
Chimney
- Min. 6" from
bottom. UMC 813.2.6.
- If more than one
side is exposed to outside, vent must be lined. UMC 813.2.6.
- Cross section must
be less than 4 times the gas vent. UMC 813.2.2.
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