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i.2.7JoiningtheAHUsections
Thesectionsmustbeplacedonthebaseframeandiftheunitisdeliveredwith100mmlegs,thesections
mustbepositioneddirectlyoppositeeachother.
1. Ensurethattheinternalfactory‐fittedrubbersealingisundamaged
2. Thesectionsarethentobepositioneddirectlyoppositeeachother.Ifthesectionsarebuiltwith
legs,theadjustablefeetcanbeusedtogetthesectionsparallelandatthesameheight.
3. Pressthesectionshard
togethersothattherubberprofilesaresoflatthattheironframesofthe
twosectionsarejoined.Strapswithtensionerasshownbelowaresuitableforpressingthesections
hardtogether.
4. Thesectionsarethentobelockedpermanentlytogetherwiththeblackplastic‐coatedSystemair
Disc‐Locks.TheDisc‐Locksaredeliveredinacartonboxplacedinsidetheunit.PlaceeachDisc‐Lock
overthe2factoryfittedlockingpins.Thediscsandlockingpinsarenotreliableforpullingthe
sectionstogether.Theyareonlysufficientforkeepingthesectionswelltogether,sojust
turneach
discgentlywiththesuppliedAllenkey.Useasequencewhereeachdiscistightenedwithonlyone
clickatatime.Iftheunitisplacedtooclosetoawallwithnospaceleftforthemountingof
SystemairDisc‐Locks,bracketsmustbeplacedinside
theunittokeepthesectionspermanently
together(bracketsforthispurposearenotdeliveredbySystemair)
i.2.8Fittingtheductwork
FlexibleductconnectionsbetweenAHUandductworkmustalwaysbeinstalled.Besurethatflexibleduct
connectionsarealmostfullystretched.(Flexibleconnectionsareorderedasaccessoriesand
theyareplaced
insidetheunit).Atthefanoutletonacentrifugalfan,theductsizeshouldbeasclosetotheoutletsizeas
possible.Avoidblockageandturbulenceatthefanoutlet.
i.2.9Riskofstackeffectbyverticalductsandwindpressureonlouvers
Onspecialoccasions
stackeffect–alsocalledchimneyeffect–intheductscreateairflowsthatdrivesthe
impellersbyturnedoffmotors.
Arotatingimpellerisapotentialhazardduringcleaningandmaintenanceoftheunit.
Eliminatethisairflowbydamperswithspringreturnmotorsforautomaticclosingofthedampers‐
evenby
powerfailure.
Important!TheSystemairairhandlingunitscanbeorderedanddeliveredwithoutdampers,andthe
installer/usermustcheckthatductsystemswiththedescribedriskofstackeffect(chimneyeffect)willbe
providedwithdampersandspringreturnmotors.