A.O. Smith BTX-80 SERIES 100 Water Heater User Manual


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21
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ue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.
TABLE 1
Number of 2” Maximum 3” Maximum 4” Maximum
90° Elbows Pipe - ft. (m) Pipe - ft. (m) Pipe - ft. (m)
1 20(6.1) 60(18.3) 120(36.6)
2 15(4.6) 55(16.8) 112(34.1)
3 10(3.0) 50(15.2) 104(31.7)
4 -- 45(13.7) 96(29.3)
5 -- 40(12.2) 88(26.8)
6 -- 35(10.7) 80(24.3)
Theminimumventlengthsforeachofthepipesizesisone90°ontopof
theunitplus2’(61cm)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rstelbow.Aftertherst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(eld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ttings
meetingASTMD-2665(UseCPVCttings,ASTMF-438forCPVCpipe
andABSttings,ASTMD-2661/3311forABSpipe).IfCPVCorABS
pipeandttings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ttingofthatmaterialmaybesubstituted
ifscreeninPVCterminalisremovedandinsertedintonewtting.
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certiedtoULCS636.
ThiswaterheaterhasbeendesigncertiedtobeventedwithPVC
pipecertied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ttingthatmustbeusedwiththisappliance.Anyoutletpiping,
ttings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
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
ttings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ttings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
tting.Thewaterheaterisshippedwithcondensatehosethat
attachestothettingonthecondensateboot.NootherTeeor
tting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exiblehosesfrombloweroutletadaptor,alongwith
anotherexiblehosefromVAAifinstalled,runtobarbttingsonvent
pipeassembly#2.Hoseisclampedbyrubberclipsandexible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gure
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lterpriortodisposal.
NOTE:Itisimportantthattheeld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overowswitch.
Caution must be used to ensure that drain is free and clear of debris
andwillnotallowbackow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tting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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