LAARS EDN Series - Installation, Operation and Maintenance Instructions - Manual (Page 11)

Endurance Page 11
per foot (21mm per meter). Be sure to take this
into consideration when choosing the vent terminal
location.
For applications requiring vertical venting
through a roof, the same limitations for length and
fittings apply (see Table 2). Vertical vents greater than
7 feet (2.1m) in length must use a condensate trap.
When vertical vent systems have horizontal
components, they must have a condensate drip tee
in the offset. All horizontal portions of the vent
system must slope a minimum 1/4" per foot toward
the condensate drip tee. Laars vertical vent kit and
individual venting components have condensate tees
that work in a vertical vent system, and therefore it
is not necessary to have an offset in a vertical vent
systems that use these parts.
The vertical vent terminal must be placed such
that the bottom of the vent cap is at least 2-feet (0.6m)
above any structure (such as the peak of a roof or
adjacent wall) within 10 feet (3.0m), and must be at
least 3 feet (0.9m) above where the vent pipe exits the
roof (see Figure 12).
Laars offers 3" vent parts for non-concentric
venting, including an in-line condensate tee and vent
caps for vertical venting. See Figure 13 for 3" vent
parts, and Figure 15 for an example of the inline
condensate in a vertical vent system.
IMPORTANT NOTE REGARDING ENDURANCE
VENTING: Regardless of the venting arrangement
being used, the flue gas vent material used with
the Endurance MUST be stainless steel special
gas vent listed to U.L. Standard 1738 and U.L.C.
Standard 636. Endurance flue gases must never
be vented into a masonry chimney or vented with
B-vent or other galvanized vent material. Endurance
units are not permitted to be common vented with
any other appliance(s), including other Endurance
appliances.
2.3 Air Source For Combustion
(when not ducted to the Endurance)
When using Category IV venting methods the
appliance draws all combustion air through its top and
from the adjacent space. When locating the appliance
in unconfined spaces in buildings, infiltration may be
adequate to provide air for combustion and ventilation.
However, in buildings of unusually tight construction,
or when locating the appliance in a confined space,
additional air should be provided and the guidelines
below must be followed:
2.3.1 Air From Inside the Building
The following method shall be used to size the
air openings for boilers that are getting all of their
combustion air from inside the building.
The confined space shall be provided with two
permanent openings communicating directly with
other spaces of sufficient volume so that the combined
volume of all such spaces meets the criteria for an
unconfined space. The total input of all gas utilization
equipment installed in the combined spaces shall be
used to determine the required minimum volume.
Each opening shall have a minimum free area of not
less than 1 in. 2 /1000 Btu/hr (220 mm 2 /kW) of the total
input rating of all gas utilization equipment in the
confined space, but not less than 100 in. 2 (645 cm 2 ).
One opening shall commence within 12 in. (30 cm) of
the top, and one opening shall commence within 12 in.
(30cm) of the bottom, of the enclosure. The minimum
dimension of air openings shall be not less than 3 in.
(8 cm).
2.3.2 All Air From Outdoors
When all air is provided from outdoors, but
not ducted directly to the Endurance, the following
methods shall be used to size the air opening(s).
a. Two permanent openings, one commencing
within 12 in. (30 cm) of the top and one
commencing within 12 in. (30 cm) of the bottom,
of the enclosure shall be provided. The openings
shall communicate directly, or by ducts, with
the outdoors or spaces (crawl or attic) that freely
communicate with the outdoors.
a1. Where directly communicating with the
outdoors or where communicating to the
outdoors through vertical ducts, each
opening shall have a minimum free area
of 1 in. 2 /4000 Btu/hr (550 mm 2 /kW) of
total input rating of all equipment in the
enclosure.
a2. Where communicating with the outdoors
through horizontal ducts, each opening
shall have a minimum free area of not less
than 1 in. 2 /2000 Btu/hr (1100 mm 2 /kW) of
total input rating of all equipment in the
enclosure.
b. One permanent opening, commencing within 12
in. (30 cm) of the top of the enclosure, shall be
permitted where the equipment has clearances
of at least 1 in. (2.5 cm) from the sides and back
and 6 in. (16 cm) from the front of the appliance.
Minimum clearance from
combustibles (vent) U.S.* 3" 8cm
Minimum clearance from
combustibles (vent) Canada 6" 15cm
Max. flue gas temp. 325°F 163°C
Max vent pressure 1.5" w.c. 0.4kPa
Max. equivalent ft. of 3" venting (any 50 15
combination of horizontal or vertical) equiv. feet equiv. meters
Max. equivalent ft. of 4" venting (any 100 30
combination of horizontal or vertical) equiv. feet equiv. meters
*Note: To use 3" (8cm) clearance, the vent must be open on at least
one side. If fully enclosed, clearance is 6" (15cm)
Table 2. Category IV Vent Parameters.