8
BLEEDING THE SYSTEM
Dependingonhowthepipeshavebeentted,airpockets
mayformwhentheheatingsystemislledwithglycol
uid.Asignthatthereisairtrappedintheheatingsys-
temisthattheheatreleasedintothepipesonlyextends
2-3feetorsofromtheboiler,eventhoughthecirculation
pumpisoperating.
Innewlylledheatingsystems,smallairbubblescan
formintheexpansiontank,creatingagurglingsound.If
thecirculationpumpisstoppedforafewseconds,the
bubbleswillusuallydisappear;however,iftheproblem
persists,bleedtheheatingsystemtoremedytheprob-
lem.
Automatic Bleeding
AllboilerssoldinNorthAmericacomewithanautomatic
airvent(seeFigure8),whichwillbleedtheheatingsys-
temautomatically.Ifyoudonothaveanautomaticair
vent,ableederscrewisttedtotheoutgoingpipefor
manualbleeding.
NOTICE
Never open the bleeders while the pump is running,
because this will induce air into the system.
Theglycolcontentshouldbecheckedattheexpansion
tankusingapHtesterbeforetoppingupwithnewliquid.
Thiswillensurethattheconcentrationofglycolinthemix-
tureisnottoohigh.Iftheuidlevelintheexpansiontank
fallsforreasonsotherthanevaporation,pleasecheck
alljoints,draincocks,andbleederscrewstoensurethat
theyarenotleaking.Besuretocheckthebleederlocated
attheendoftheconvector.Besuretothoroughlyclean
upanypuddlesofleakedglycol.Rinsetheareawith
waterandwipeuptheexcess.Therecommendedglycol
productisconsiderednontoxic,butwestillrecommend
thatyouusecaretopreventaccidentalingestionbychil-
drenorpets.
FILLING THE HEATING SYSTEM WITH
GLYCOL FLUID
Fillthesystemthroughtheexpansiontank,eithermanu-
allyorusingtheAldellingpump,whichbothtopsupand
bleedsthesystem.Topurchaseallingpump,contact
yourAldedealer.Formanuallling,removenut
(SeeFigure7)fromthetank.Slowlypourtheglycolmix-
tureintothetank.Bleedtheheatingsystem(seedirec-
tionsbelow).Topupwithmoreliquidifthelevelhasfallen
afterbleeding.Bleedanewlylledheatingsystemregu-
larlyduringtherstdaystheheatingsystemisinopera-
tion.
NOTICE
Any vessels used to carry the uid must be spot-
lessly clean and the pipes in the system must be
free of contamination. This will prevent the growth
of bacteria in the system.
Manual Bleeding
Tobleedtheheatingsystemmanually,followthesteps
below:
1. Switchoffthecirculationpump.
2. Openthebleederscrewandleaveitopenuntilit
startstodischargewater.
3. Closethebleederscrew.
4. Opentheremainingbleederscrewsinthesystem
(pleaserefertotheinstructionmanualoftheRVfor
theirlocations).
5. Leavethebleederscrewsopenuntiltheystartdis-
charginguid,andthenclosethem.
6. StarttheLPgasboiler.
7. Startthecirculationpumpandletitrunforawhile.
Checkthatthepipesandconvectorsaroundthe
vehicleareheatingup.
Persistent Air Lock
Ifairlockpersists,trythefollowing:
Single-axle trailers:
1. Stopthecirculationpump.
2. Lowerthefrontofthetrailerasfaraspossible.Leave
itinthispositionforafewminutestoallowtheairto
travelupwardsintheheatingsystem.
3. Openthebleederscrewatthehighestpoint.Leaveit
openuntilitdischargesglycoluid.
4. Raisethefrontofthetrailerasfaraspossibleand
repeattheprocedureinthisposition.
5. Positionthetrailerhorizontallyandstartthecircula-
tionpump.
6. Checkthatthepipesandconvectorsaroundthevehi-
cleareheatingup.
Motorhome or twin-axle trailers:
Theeasiestwaytobleedtheheatingsystemistoplace
thevehicleonaslopingsurfaceortoraiseoneendof
thevehicleusingajack.Bleedtheheatingsystemas
describedabove.Alternativelytheheatingsystemcanbe
bledusingtheapprovedllingpump.Toobtainapump,
checkwithyourAldedealer.
Figure 8. Automatic Air Vent