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Vertical vents of the induced draft JVH boilers must
be installed in accordance with the code requirement
for Category 1, Fan Assisted Appliances. Follow the
requirements as indicated in the latest edition of ANSI
Z223.1/NFPA 54, sizing of Category I Venting System
and Appendix G, or in Canada, follow the instruction
of CAN/CGA-B149 installation code.
An unused lined chimney can be used as a raceway
for single wall vent pipe, (see Figure 3). Never run
vent pipe through a flue that has another appliance
attached to it.
3D-1. Horizontal Venting - Category III
(JVH only)
When venting is horizontal, or cannot meet the
requirements of Category I, it can develop positive
pressure and must be installed in accordance with
this section and the specific vent manufacturer's
instructions. Common venting is not allowed in
Category III systems.
OUTSIDE WALL
VENT
SYSTEM
THIMBLE
BOILER
VENT TERMINAL
HOOD
Figure 5. Horizontal Venting.
3D-2. Vent Connections (JVH only)
The vent system must be gas tight. All seams and
joints must be sealed with silicone sealant or adhesive
tape having a minimum temperature rating of 400°F
(204ºC). Use at least three corrosion resistant screws at
each slip joint, when required.
BOILER VENTING
DETAIL
SHEET METAL
SCREWS
*
12" (305mm)
MIN.
CAULK ENTIRE
JOINT, INCLUDING
THE SCREWS
*WHEN HORIZONTAL RUN
EXCEEDS 5 FT. (1.5m)
For best results, horizontal vent systems should
be as short and straight as possible. Material of vent
connectors shall be as follows:
Description
High Temperature
RTV
2" (51mm) wide
Aluminum foil tape
- adhesively backed
2" (51mm) wide
Aluminum foil tape
- adhesively backed
Vent Sealing Materials.
Materials
In U.S.A.: UL type 304, 316 or 294-C
stainless steel or equal 26 gauge minimum.
In Canada: Use "BH-Type" vent
material certified to ULD-S636 Class I
(more than 135°C, but not more than 245°C
flue gas temperature), made of AL29-4C
stainless steel or equal.
Do not use plastic venting of any kind.
The boiler vent collar must be fastened to the vent
pipe with rustproof metal screws no longer than 1/2"
(13mm) and sealed with high temperature (500ºF /
260ºC) silicone sealant. For larger diameter vent pipes,
use a sealed reducer fastened directly to the boiler
collar and seal all joints as indicated in Figure 5.
Allow the sealant to cure for 24 hours before operating
the boiler.
The entire vent system must not exceed the size
specified in Table 6.
The following criteria must be observed:
1.
Attach a vertical pipe at least 12" (305mm) high
to the boiler outlet before the horizontal run if
run exceeds 5 feet (see Figure 5).
2.
Support the vent run at 3' (.9m) intervals with
overhead hangers.
Diameter
Size
in.
mm
4
50 - 160
102
225
4
102
6
225
152
For each elbow eliminated, add 5' (1.5m) of allowable vent.
Table 6. Horizontal Venting Configuration.
3.
Pitch down the vent run, toward the vent terminal
(hood), 1/4" per foot (20mm per meter).
4.
Do not locate any joint screws at the bottom of
the vent run.
3D-3.
Vent Termination (JVH only)
The side wall vent terminal (hood), Laars Part
LAARS Heating Systems
Manufacturer
Product
Dow Corning
Trade Mate
Product
Venture
#3243
3M
Product #433
Vent Length
Up to a maximum
of 55' (17m) of
equivalent pipe run
(including required
elbows).
Horizontal Run Length
No. of
Elbows
ft.
35
4
2
10
35
4
m
10.7
3.0
10.7
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