Planning The Vent System; Condensate - A.O. Smith BTX-80 SERIES 100 Instruction Manual

plannInG the vent sYsteM

Plan the route of the vent system from the discharge of the blower
to the planned location of the vent terminal. Refer to VAA instruction
on page 25 while planning the vent system.
1. Layout total vent system to use a minimum of vent pipe and elbows.
2. This water heater is capable of venting flue gases equivalent to
25' (7.6 m) of 2" pipe, 65' (19.8 m) of 3" pipe, or 128' (39.0 m) of
4" pipe as listed in Table 1.
Number of 2" Maximum
90° Elbows Pipe - ft. (m)
1 20 (6.1)
2 15 (4.6)
3 10 (3.0)
4 --
5 --
6 --
The minimum vent lengths for each of the pipe sizes is one 90° on top of
the unit plus 2' (61 cm) of straight pipe and the appropriate termination.
note: The equivalent feet (m) of pipe listed above are exclusive
of the termination. That is, the termination, with an installed
screen, is assumed to be in the system and the remainder of the
system must not exceed the lengths discussed above.
3. The blower discharge adapter is made to accept only straight
sections of 2" pipe. To start, a minimum of 2 inches (5.1 cm) of 2"
pipe must be attached to the blower discharge, see Figure 17.
If using 2" inch vent pipe:
A minimum of 2 inches (5.1 cm) must be attached to the blower
before the first elbow. After the first elbow add the additional
venting required for the installation. The total system cannot
exceed the lengths discussed above, where each elbow is equal
to 5 feet (1.5 m) of straight pipe.
If using 3" or 4" inch vent pipe:
Two inches (5.1 cm) of pipe must be attached to blower discharge before
adding a reducer to acquire desired pipe diameter. An appropriately
sized 45 degree schedule 40 DWV elbow (field supplied) vent terminal
must be obtained with an equivalent screen (supplied in vent kit).
The total system cannot exceed equivalent pipe lengths discussed
above where each elbow is equal to 5 feet (1.5 m) of straight pipe
(3" vent pipe) or 8 feet (2.4 m) of straight pipe (4" vent pipe).
u.s. Installations
note: This unit can be vented with PVC pipe materials (DWV
ASTM-D2665 or CSA B181.2; Schedule 40, 80, 120 ASTM-D1785
or CSA B137.3; or SDR Series ASTM-D2241 or CSA B137.3), CPVC
pipe materials (CPVC41 ASTM-D2846 or CSA B137.6; Schedule 40,
80 ASTM-F441 or CSA B137.6; or SDR Series ASTM-F442), ABS pipe
materials (Schedule 40 DWV ASTM-D2661 or CSA B181.1). Fittings,
other than TERMINATION should be equivalent to PVC-DWV fittings
meeting ASTM D-2665 (Use CPVC fittings, ASTM F-438 for CPVC pipe
and ABS fittings, ASTM D-2661/3311 for ABS pipe). If CPVC or ABS
pipe and fittings are used, then proper cement must be used for all joints,
including joining pipe to Termination (PVC Material). If local codes do not
allow use of PVC termination when a material other than PVC is used
for venting, then an equivalent fitting of that material may be substituted
if screen in PVC terminal is removed and inserted into new fitting.
PVC Materials should use ASTM D-2564 Grade Cement; CPVC
Materials should use ASTM F-493 Grade Cement and ABS Materials
should use ASTM D-2235 Grade Cement.
canadian Installations
Installation of this water heater must comply with CAN/CSA B149.1
- Natural Gas and Propane Installation Code which requires the vent
system components be certified to ULC S636.
This water heater has been design certified to be vented with PVC
pipe certified and marked as complying with ULC S636. This water
heater is supplied with a 2 inch 22.5 degree termination elbow that is a
special fitting that must be used with this appliance. Any outlet piping,
fittings and glue used to vent this appliance that is not supplied by the
manufacturer must comply with the ULC S636 requirements.
If water heater is being installed as a replacement for an existing power
vented heater in pre-existing venting, a thorough inspection of existing
taBle 1
3" Maximum 4" Maximum
Pipe - ft. (m) Pipe - ft. (m)
60 (18.3) 120 (36.6)
55 (16.8) 112 (34.1)
50 (15.2) 104 (31.7)
45 (13.7) 96 (29.3)
40 (12.2) 88 (26.8)
35 (10.7) 80 (24.3)
venting system must be performed prior to any installation work. Verify
that correct material as detailed above has been used, and that minimum
or maximum vent lengths and terminal location as detailed in this manual
have been met. Carefully inspect entire venting system for any signs
of cracks or fractures, particularly at joints between elbows and other
fittings and straight runs of vent pipe. Check system for signs of sagging
or other stresses in joints as a result of misalignment of any components
in system. If any of these conditions are found, they must be corrected in
accordance with venting instructions in this manual before completing
installation and putting water heater into service.
note: a. For water heaters in locations with high ambient
temperatures (above 100°F) it is recommended that CPVC pipe
and fittings be used. B. A 22.5 degree elbow (2" vent pipe) or a 45
degree elbow (3" and 4" vent pipe) with an installed screen VENT
TERMINAL must be used in all cases.
4. There will be some installations where condensate will be formed
in the horizontal runs of the vent system. This condensate will
run into the condensate boot attached to the blower and out the
fitting. The water heater is shipped with condensate hose that
attaches to the fitting on the condensate boot. No other Tee or
fitting is required. See Figures 17, 20 and 21.

condensate

This water heater is a condensing unit and requires a drain to be located
in close proximity to allow condensate to drain safely. One hose from
blower housing, two flexible hoses from blower outlet adaptor, along with
another flexible hose from VAA if installed, run to barb fittings on vent
pipe assembly #2. Hose is clamped by rubber clips and flexible hoses
by a clamp on jacket top cover. See Figure 17. Condensate drains from
the unit at the exhaust tee located at the bottom of the unit (see figure
16). Condensate from this water heater is mildly acidic. Please note
that some local codes require that condensate is treated by using a pH
neutralizing filter prior to disposal.
NOTE: It is important that the field supplied drain lines beyond
the 1/2" adaptor of vent pipe assembly #1 should be installed
continuously tilted downward toward an appropriate drain. See Figure
16. If these instructions are not followed or if condensate drain line
is blocked, water will spill from condensate trap. Do not block the
holes in the hex plug on top of a small tee in vent pipe assembly
#1. As with every water heater installation, a drain pan should be
used to prevent water damage to surrounding area. If necessary,
a condensate pump with an incorporated reservoir may be used to
pump water to an appropriate drain. To avoid condensate spillage,
select a pump with an overflow switch.
Caution must be used to ensure that drain is free and clear of debris
and will not allow backflow through the condensate drain line.
Consideration must be given to avoid freezing of the condensate
lines which could result in excessive build up of condensate inside
the water heater. Waterproof heat tape may be required to prevent
freezing of condensate lines. Please ensure that the outlet of
condensate drain does not create a slippery condition which could
lead to personal injury. Care should be taken to ensure there is no
kink or twist in any condensate hose. If a VAA is not installed, the
unused barb fitting in vent pipe assembly #2 should be plugged using
one of the break-away plugs.
Breathing Hazard - Carbon Monoxide Gas
•
Do NOT block the holes in the hex plug of vent pipe
assembly #1.
•
Do NOT elevate any portion of the field supplied drain
line beyond the 1/2" adaptor above the adaptor. This
must be true for entire length of the drain line including
the exit into an appropriate drain.
•
Condensate lines must be free and clear of debris and
must not allow back flow through drain line. Condensate
lines must be able to flow freely to an appropriate drain.
•
Do not allow condensate lines to become crimped closed.
•
Analyze entire vent system to make sure that condensate
will not become trapped in a section of vent pipe and
therefore reduce open cross sectional area of vent.
Breathing carbon monoxide can cause brain damage or death.
Always read and understand instruction manual.
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