35
x Wiring
1) LineVoltage(120VAC)Connections(Fig9.1)–Thelinevoltageconnectionsarelocatedinthejunctionbox
ontherightsideofthevestibule:
• Black–Linevoltage“hot”
• White–“Neutral”forboilerandcirculators
• Red–“Heating”circulator“hot”
• Blue–“IndirectWaterHeater“circulator“hot”
• Green–Groundconnection
2) Maximumcirculatorcontinuouscurrentdrawis2A.WhenPipingMethod#1isused,itmaybedesirableto
usetheboilertodirectlycontroltheprimarycirculatorinadditiontothesecondarycirculator.Ifthisisdone,
controlbothheatingcirculatorsusingarelaywitha120VACcoil,suchasaHoneywellR4222,asshownin
Figure9.3.Selectarelaywithacontactratinginexcessofthecombineddrawofthetwocirculators.
3) LowVoltageConnections(Fig9.1)–Theseconnectionsarescrewterminalslocatedontheterminalstripnext
tothejunctionboxontheleft:
• Terminals1and2–“Heating”thermostatconnections
• Terminals3and4–“ExternalLimitControl”connections
• Terminals5and6–“OutdoorResetSensor”connections
• Terminals7and8–“DomesticIndirectWaterHeater”thermostatconnections
• Terminal9–“FlameSignalReading”
• Heatanticipatorsettingforthethermostatconnectionis0.1Awhenthermostatisconnecteddirectlyto
terminals1and2.
4) Iftheoutdoorsensorisconnectedtoterminals5and6,theboilerwilladjustthetargetspaceheatingsetpoint
supplywatertemperaturedownwardsastheoutdoorairtemperatureincreases.Ifused,thissensorshouldbe
locatedontheoutsideofthestructureinanareawhereitwillsensetheaverageairtemperaturearoundthe
house.Avoidplacingthissensorinareaswhereitmaybecoveredwithiceorsnow.Ingeneral,locations
wherethesensorwillpickupdirectradiationfromthesunshouldalsobeavoided.Avoidplacingthesensor
nearpotentialsourcesofelectricalnoisesuchastransformers,powerlines,anduorescentlighting.Wirethe
sensortotheboilerusing22gaugeorlargerwire.Aswiththesensor,thesensorwiringshouldberoutedaway
fromsourcesofelectricalnoise.Whereitisimpossibletoavoidsuchnoisesources,wirethesensorusinga
2conductor,ULTypeCM,AWMStyle2092,300Volt60°Cshieldedcable.Connectoneendoftheshielding
onthiscabletoground.
warNINg
all wIrINg aND grOuNDINg musT bE DONE IN aCCOrDaNCE wITh
THE AuTHoRITy HAVING juRISDICTIoN oR, IN THE ABSENCE oF SuCH
REquIREMENTS, WITH THE NATIoNAL ELECTRICAL CoDE (ANSI/NFPA 70).
CauTION
• WHEN MAkING LoW VoLTAGE CoNNECTIoNS, MAkE SuRE THAT No
ExTErNal POwEr sOurCE Is PrEsENT IN ThE ThErmOsTaT Or lImIT
CIRCuITS. IF SuCH A PoWER SouRCE IS PRESENT, IT CouLD DESTRoy
THE BoILER’S MICRoPRoCESSoR CoNTRoL (MCBA). oNE ExAMPLE
Of aN ExTErNal POwEr sOurCE ThaT COulD bE INaDVErTENTly
CONNECTED TO ThE lOw VOlTagE CONNECTIONs Is a TraNsfOrmEr
IN OlD ThErmOsTaT wIrINg.