A.O. Smith 310 - COMPUTER BOARD RESET AND OHCF CHECK

TroubleshootingGuide
23|Page
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ADJUSTINGMAN IFOLDPRESSURE: 
Themanifoldgaspressureofthetanklessunitcanbeadjustedbythefollowingprocedure.
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Adjustingthemanifoldpressurecancauseunexpectedcombustionconditionsduring
operation,whichcancauseahealthhazard,damagethetanklessunit,andorshortenits
lifespan.Therefore,changingthemanifoldpressureisnotrecommendedunless
there
areverystrongreasonstodoso(e.g.highelevationinstallations),andwiththe
consultationoftheTechnicalServiceDepartment.
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1) Setupthemanometerbyfollowingsteps1through4onthe“Checkingmanifoldgas
pressure”proceduresonp.21.
2) Pressandholddownthe“MIN”button
onthecomputerboard.Whileholding
downthe“MIN”button,presseitherthe
“INCREASE”or“DECREASE”buttonto
increaseordecreasethemanifoldgas
pressure,respectively(Figure5.18).
Refertothemanometertoverifythat
pressurehasbeensettodesiredvalue.
3) Nowpressandholddownthe“MAX”
button
onthecomputerboardtochange
themaximumburnpressure.
4) Repeatedlyadjusttheminimumand 
maximumpressuresagainuntilboth
levelsarestableandtherearenomorechangesfromthepreviousiteration.
5) Afterthemanifoldgaspressurehasbeenset,deactivatetheunit(stopallwaterrunning
throughtheunit),removethemanometertube,andreplacetheportscrew.
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RESETTINGTHECOMPUTERBOAR D:
1) Verifythatthereisnowaterflowingthrough
theunit. 
2) Ifatemperatureremotecontrollerhasbeen
installed,turnthepowerofftotheremote.
3) Turnoffpowertotheunit,andthenturnon
again.
4) Pushandholdthe“INC”and“DEC”buttons
onthe
computerboardsimultaneouslyfor
severalsecondsuntiltheredLEDlightsup
solid.
5) UsethePowerON‐OFFswitch/GFItoturnthe
unitoffthenonagain.Thecomputerboardis
reset.
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WARNING
Computerboard
MAX
MIN
Increase
Decrease
Figure20
Figure21