A.O. Smith BL-80 - Water Piping; WARNING Toxic Chemical Hazard; Potable and Space Heating Water Use; Closed Water Systems

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WATER PIPING
WATER (POTABLE) HEATING AND SPACE HEATING
Thiswaterheatershallnotbeconnectedtoanyheatingsystems
orcomponent(s)usedwithanon-potablewaterheatingappliance.
Allpipingcomponentsconnectedtothisunitforspaceheating
applicationsshallbesuitableforusewithpotablewater.
Toxicchemicals,suchasthoseusedforboilertreatmentshallnot
beintroducedintothissystem.
Whenthesystemrequireswaterforspaceheatingattemperatures
higherthanrequiredfordomesticwaterpurposes,amixingvalve
mustbeinstalled.PleaserefertoFigure6forsuggestedpiping
arrangement.
Thesewaterheaterscannotbeusedinspaceheatingapplications
only.
CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements or
such conditions as high line pressure, among others, have
installed devices such as pressure reducing valves, check
valves,andbackflowpreventers.Devicessuchasthesecause
thewatersystemtobeaclosedsystem.
THERMAL EXPANSION
Aswaterisheated,itexpands(thermalexpansion).Inaclosed
systemthevolumeofwaterwillgrowwhenitisheated.Asthe
volumeofwatergrowstherewillbeacorrespondingincreasein
water pressure due to thermal expansion. Thermal expansion
cancauseprematuretankfailure(leakage).Thistypeoffailure
is not covered under the limited warranty. Thermal expansion
canalsocauseintermittentTemperature-PressureReliefValve
operation: water discharged from the valve due to excessive
pressurebuildup.Thisconditionisnotcoveredunderthelimited
warranty.TheTemperature-PressureReliefValveisnotintended
fortheconstantreliefofthermalexpansion.
A properly sized thermal expansion tank must be installed on
all closed systems to control the harmful effects of thermal
expansion.Contactalocalplumbingservicetechniciantohave
athermalexpansiontankinstalled.
FIGURE 7.
NOTE: To protect against untimely corrosion of hot and cold
waterttings,itisstronglyrecommendedthatdi-electricunions
orcouplingsbeinstalledonthiswaterheaterwhenconnectedto
copperpipe.
Figure7showsthetypicalattachmentofthewaterpipingtothe
water heater.
TEMPERATURE-PRESSURE RELIEF VALVE
Explosion Hazard
Temperature-Pressure Relief Valve
must comply with ANSI Z21.22-
CSA 4.4 and ASME code.
Properly sized temperature-
pressure relief valve must be
installed in opening provided.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
Thiswaterheaterisprovidedwithaproperlyrated/sizedand
certifiedcombinationTemperature-PressureReliefValve(T&P
valve)bythemanufacturer.Thevalveiscertifiedbyanationally
recognizedtestinglaboratorythatmaintainsperiodicinspection
ofproductionoflistedequipmentofmaterialsasmeetingthe
requirementsforReliefValvesforHotWaterSupplySystems,
ANSIZ21.22•CSA4.4,andthecoderequirementsofASME.
Ifreplaced,thenewT&Pvalvemustmeettherequirements
oflocalcodes,butnotlessthanacombinationTemperature-
PressureReliefValverated/sizedandcertifiedasindicatedin
theaboveparagraph.Thenewvalvemustbemarkedwitha
maximumsetpressurenottoexceedthemarkedhydrostatic
workingpressureofthewaterheater(150psi=1,035kPa)
andadischargecapacitynotlessthanthewaterheaterBtu/
hr or kW input rate as shown on the water heater’s model
ratinglabel.