A.O. Smith 310 - DESCALING THE UNIT; DESCALING PROCEDURE

TroubleshootingGuide
32|Page
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DESCALINGTHEUNIT
Hardwaterisasevereproblemforthecoppercoilsinsideheatexchangers.Heatexchanger
failureduetoscalebuildupfromhardwaterconditionsisNOTcoveredbywarranty.Itishighly
suggestedthatascaleinhibitorbeinstalledbeforethecoldwaterinletafterthisprocedureis
done.
1) TOOLS
‐Gatherthefollowingmaterialstogether:
a. Pump:Thepumpshouldprovideaminimumof
1GPMthroughtheheater
b. CleaningSolution:Foodgradecitricacid,food
gradephosphorusacid.
c. Waterhoses
d. Bucket
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2) SETUP
‐Disconnectpowertotheunit
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3) WATERLINES
–Assumesisolationvalveswithdrain
portsareinstalled
a. Isolatetheunitbyclosing theincoming/outgoing
waterisolationvalvesCandD.
b. Connecthoses/pumptothedrainportsofthe
isolationvalves:OutletofthepumptovalveB,
andanotherhosefromValveAtothebucket.
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4) PUMP
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a. Fillthebucketwith5gallonsofdilutedsolution.
Dilutionratiodependsonthecleaningsolution
used.
b. Placethepumpintothebucketifitissubmersible,
oruseaninlethoseintothebucketifitisnot
submersible.
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5) DESCALE
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a. OpenvalvesAandB.
b. Circulatedescalingsolutionthroughtheunitfor45minutes.
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6) CLEANSETHESYSTEM
–Flushthechemicalsoutoftheheatexchangerwithfreshwater.
a. ClosevalveAandB.
b. OpenvalveDandrunfreshwaterthroughthePRVfor15minutes.
c. Cleanthefilterafterflushingtheunitwithfreshwater.
d. Oncetheunitisflushedandcleansed,closeAandB,openCandD,andreconnectpowertothe
unit.
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321923‐000
Figure35