Specifications

11
C
B
A
3.5 Principle of operation
CombustionSystem
Thecombustionsystemisbasedonafullymodulatingforceddraftcombustionairblower,anegative
pressureregulatorgasvalveanda100%premixburner.Onacallforhumidity,thecombustionair
blowerstartsandcreatesanegativepressureacrossanoricelocatedattheairinlet.Theblower
starts for a moment to purge the system, then the hot surface ignitor is activated. During this time
theelectronicignitionmoduledoesadiagnosticcheckofsafetysystemsincludingtheairproving
switchwhichsensesthenegativepressureattheairinlet.
Afterthefunctionofthesafetysystemshasbeenveried,thegasvalvewillopenandthegas/air
mixtureisignitedbythehotsurfaceignitor.Ifameissensedbytheamesensorwithin7 seconds
thegasvalveremainsopenandcombustioncontinues.Ifameisnotsensed,theabovesequence
isrepeatedamaximumofthreetimesafterwhichtheignitionmodulewilllockoutandarespective
errormessagewillappearinthedisplay.
ThegasvalvemaintainsaconstantratioofairtoNaturalGasorPropaneindependentofblower
speedorexternalconditions.Thisairandfuelisthoroughlymixedintheblowerandthenforced
throughtheburnerportswhereignitionoccurs.
Hotproductsofcombustionareforcedthroughabafeinsidetheheatexchangerandthenvented
outside.Theheatexchangerhaslargeverticalsurfacestominimizescalebuild-upandpromotescale
sheddingtothebottomofthetank.Thisself-cleaningactionhelpstomaintaintheefciencyofthe
heatexchangerwhilethesmoothsurfacesallowforeasycleaningwhennecessary.
TheGS40hasasinglecombustionchamber/heatexchanger.Thecombustionsystemisduplicated
onlargerunitswithmultiplechambersinsideacommontank.
Regulation of the water level in the tank
Thelevelinthewatertankiscontinuouslymonitoredbythelevelunit.Oninitialstart-up,thecontrol
unitchecksthefunctionofthelevelunit.Duringthistestthetankislleduprsttolevel“A”,then
drainedtolevel“C”andlledupagaintolevel“A”.Assoonaslevel“B”isreachedandthetestofthe
levelunitwassuccessfulthehumidierisreadyforoperation,ifahumidicationdemandispresent
the combustion process starts.
Level unit
Pressure equalizer
Filling chamber
Vacuumbreak
Mainllline
Doublellvalve
Drain outlet
Drain pump
Auxiliarydrain
Mixingpipe