LAARS EDN Series - Installation, Operation and Maintenance Instructions - Manual (Page 8)

Page 8 LAARS HEATING SYSTEMS
Figure 11. Non-Concentric Combustion Air Source.
1,000 BTU/hr (293W) boiler input, but not be
less than 100 square inches (645.2 sq. cm). These
openings shall freely connect with areas having
adequate infiltration from outside.
3. When all air is provided from outdoors, the
confined space shall be provided with one
opening within 12" of the ceiling. This opening
shall connect directly, or by ducts, with outdoors
or spaces (crawl or attic) that freely connect
with the outdoors, and shall have a minimum free
area of:
a.
1 sq. in. per 3000 BTU/hr (7 cm 2 /kw) of the
total input rating of all equipment located in
the enclosure, and
b. Not less than the sum of the areas of all
vent connectors in the confined space.
2.6 Connecting Special Gas Vent
to the Appliance
Part number 2400-372 is used with a vent
terminal (p/n 2400-277) to secure the 3 inch special
gas vent to the flue outlet of the appliance. Heat-Fab
pipe or fittings (p/n 2400-350 or 2400-352) or the male
end of Z-Vent pipe (Z-Vent # 02 SVEPXX030) may
be installed over the flue outlet of the Appliance (see
Figure 10).
2.7 Securing Special Gas Vent
Attach p/n 2400-277 with sheet metal screws to
the 5" collar on the appliance with a short piece of 5"
pipe or to the end of the 5" combustion air duct. Attach
p/n 2400-372 bracket and tighten clamp. Form the tabs
on the bracket onto the special gas vent pipe and
secure the tabs with the 3" clamp. After the clamp has
been tightened, fold the end of the tabs down over the
clamp (see Figure 10).
DO NOT use screws in any portion of the 3"
special gas vent.
When providing combustion air from another
location, the connection of the 5" duct to the appliance
must be secured with sheet metal screws.
Each 5" joint in the 5" duct must be secured with
sheet metal screws.
In this type of installation, p/n 2400-372 must be
used to secure the special gas vent at the point where it
exits the duct. The combustion air supply should be
protected from debris entering the duct with an
appliance vent terminal, p/n 2400-277, as shown in
Figure 8 or with a large mesh screen.
Follow the special gas vent manufacturer's
instructions for cleaning and sealing all parts before
assembling.
Apply ¼" bead of silicone sealer (GE108 or
Novagard 400) to the 3" flue outlet of the appliance
approximately 1" from the end.
Slide 3" inner vent pipe or 1-880 adapter, when
using outer 3" telescoping section, over the appliance
flue outlet and push down to stop (do not force pipe
beyond stop).
Apply another bead of silicone around this joint
and smooth out.
Apply ¼" bead of silicone to subsequent 3" joints.
An alternate, nonconcentric combustion air
source may be installed (as shown in Figure 11),
provided that the minimum 4" diameter combustion air
duct does not exceed 15' (4.6m). Termination should
include an air screen and be located in a qualified air
space (see Section 2.5) or outside.
SECTION 3.
3.1 Gas Piping
The appliance requires an inlet gas pressure of at
least 4" w.c. (1.0kPa) and no greater than 13" WC
(3.2kPa). Check with your local gas utility or supplier
for availability of this pressure range.
Refer to Table 3 to size the supply piping to
minimize pressure drop between meter or regulator
and unit.
Figure 10. Special Gas Vent Connection.