A.O. Smith BL-100 User Manual

10
GAS SUPPLY SYSTEMS
Low pressure building gas supply systems are dened as those
systemsthatcannotunderanycircumstancesexceed14”W.C.
(1/2PSIGauge).Thesesystemsdonotrequirepressureregulation.
Measurementsshouldbetakentoinsurethatgaspressuresarestable
andfallwithintherequirementsstatedonthewaterheaterratingplate.
readingsshould be takenwith all gas burning equipment off (static
pressure)andwithallgasburningequipmentrunningatmaximumrate
(dynamicpressure).Thegassupplypressuremustbestablewithin1.5”
W.C.fromstatictodynamicpressuretoprovidegoodperformance.
Pressuredropsthatexceed1.5”W.C.maycauseroughstarting,noisy
combustionornuisanceoutages.Increasesorspikesinstaticpressure
duringoffcyclesmaycausefailuretoigniteorinseverecasesdamage
toappliancegasvalves.Ifyourlowpressuresystemdoesnotmeet
theserequirements,theinstallerisresponsibleforthecorrections.
HighPressurebuildingsupplysystemsusepressuresthatexceed
14” W.C. (1/2 PSI Gauge).These systems must use eld supplied
regulatorstolowerthegaspressuretolessthan14”W.C.(1/2PSI
Gauge).Appliancesrequiregasregulatorsthatareproperlysizedforthe
waterheaterinputanddelivertheratingplatespeciedpressures.Gas
supplysystemswherepressureexceeds5PSIoftenrequiremultiple
regulatorstoachievedesiredpressures.Systemsinexcessof5PSI
buildingpressureshouldbedesignedbygasdeliveryprofessionals
forbestperformance.Waterheatersconnectedtogassupplysystems
thatexceed14”W.C.(1/2PSIGauge)atanytimemustbeequipped
withagassupplyregulator.
GAS PRESSURE REQUIREMENTS
BL-100naturalgasmodelrequiresaminimumgassupplypressureof
5”w.c.(1.25kPa);BL-80naturalgasmodelrequiresaminimumgas
supplypressureof6”w.c.(1.49kPa).Theminimumsupplypressure
is measured while gas is owing (dynamic pressure). The supply
pressure(dynamic)shouldneverfallbelowthespeciedminimum
supplypressure.Thesupplypressureshouldbemeasuredwithallgas
redappliancesconnectedtothecommonmainringatfullcapacity.If
thesupplypressuredropsmorethan1.5”W.C.(0.37kPa)asgasbegins
toowtothewaterheaterthenthesupplygassystemincludingthe
gaslineand/orthegasregulatormayberestrictedorundersized.See
SupplyGasregulatorsectionandGasPipingsectionofthismanual.
Thegasvalveonallmodelshasamaximumgassupplypressurelimit
of14”W.C.(3.48kPa)Themaximumsupplypressureismeasured
whilegasisnotowing(staticpressure).
SUPPLY GAS REGULATOR
Themaximumallowablegassupplypressureforthiswaterheater
is14.0inchesW.C.(3.48kPa).Installapositivelock-upgaspressure
regulatorinthegassupplylineifinletgaspressurecanexceed14.0
inchesW.C.(3.48kPa)atany time. regulators mustbesized/used
accordingtomanufacturer’sspecications.
Ifapositivelock-upregulatorisrequiredfollowtheseinstructions:
1. Positivelock-upgaspressureregulatorsmustberatedatorabove
 theinputBtu/hrratingofthewaterheatertheysupply.
2. Positivelock-upgaspressureregulator(s)shouldbeinstalledno
 closerthan3feet(1meter)andnofartherthan8feet(2.4meters)
 ofequivalentlengthfromthewaterheater’sinletgasconnection.
3. Afterinstallingthepositivelock-upgaspressureregulator(s)aninitial
 nominalsupplypressuresettingof7.0”W.C.whilethewaterheater
 isoperatingisrecommendedandwillgenerallyprovidegood
 waterheateroperation.Someadditionaladjustmentmayberequired
 latertomaintainasteadygassupplypressure.
4. When installing multiple water heaters in the same gas supply
 system it is recommended that individual positive lock-up gas
 pressureregulatorsbeinstalledateachunit.
MIXING VALVES
Water temperature over 125°F (52°C)
can cause severe burns instantly
resulting in severe injury or death.
Children, the elderly and the physically
or mentally disabled are at highest risk
for scald injury.
Feel water before bathing or showering.
Temperature limiting devices such as
mixing valves must be installed when
required by codes and to ensure safe
temperatures at fixtures.
Waterheatedtoatemperaturewhichwillsatisfyclotheswashing,dish
washing,andothersanitizingneedscanscaldandcausepermanent
injuryuponcontact.Shortrepeatedheatingcyclescausedbysmall
hotwaterusescancausetemperaturesatthepointofusetoexceed
thewaterheater’stemperaturesettingbyupto20°F(11°C).
Somepeoplearemorelikelytobepermanentlyinjuredbyhotwater
than others. These include the elderly, children, the inrm and the
physically/mentally disabled.Table 2 shows the approximate time-
to-burnrelationshipfornormaladultskin.Ifanyoneusinghotwater
provided by the water heater being installed ts into one of these
groupsorifthereisalocalcodeorstatelawrequiringacertainwater
temperatureatthepointofuse,thenspecialprecautionsmustbetaken.
In addition to using the lowest possible temperature setting that
satisesdemandoftheapplicationaMixingValveshouldbeinstalled
atthewaterheaterorathotwatertapstofurtherreducesystemwater
temperature.SeeFigure6.
Mixing valves are available at plumbing supply stores. Consult
a Qualied Installer or Service Technician. Follow mixing valve
manufacturer’sinstructionsforinstallationofthevalves.
TABLE 2.
Water
Temperature°F
Timefor
1stDegreeBurn
(LessSevereBurns)
TimeforPermanentBurns
2nd&3rdDegree
(MostSevereBurns)
110
(normalshowertemp.)
116 (painthreshold)
116 35minutes 45minutes
122 1minute 5minutes
131 5seconds 25seconds
140 2seconds 5seconds
149 1second 2seconds
154 instantaneous 1second
(U.S.GovernmentMemorandum,C.P.S.C.,PeterL.Armstrong,Sept.15,1978)
HOT WATER
OUTLET
TO TANK
INLET
CHECK
VALVE
MIXING
VALVE
COLD
WATER
INLET
TEMPERED WATER
OUTLET
12” TO 15”
(30-38 cm)
CHECK
VALVE
FIGURE 6.
INSTALLATION REQUIREMENTS

A.O. Smith BL-100 Specifications

General

Brand	A.O. Smith
Model	BL-100
Category	Water Heater
Language	English