Tech Controllers ST-976 - Fuel Selection

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20
Watertankpriority
Inthismode,thewatertank(DHW)pumpoperatesuntilthepre‐setDHWtemperatureisreached(thevalves
closetothemaximumandthevalvepumpsareswitchedoff).Afterthepre‐settemperaturehasbeenreached,
thepumpisdisabledandthecontrolleractivatestheCHpumpandthemixingvalves.Whenthewatertank
temperaturedropsbelowthepre‐setvalueminushysteresis,DHWpumpisenabledagainandthevalvesare
disabled.
NOTE
Ifthepre‐setwatertanktemperatureishigherthanthepre‐setCHboilertemperature,thepumpwill
notbeactivatedinordernottocooldownthewater.
Parallelpumps
InthismodetheCHpumpoperatesabovethepumpactivationthreshold.DHWpumpisactivatedatthesame
time in order to heat the water tank. Once DHW pre‐set temperature has been reached, DHW pump is
disabled.ItisenabledagainwhenthetemperaturedropsbyDHWhysteresisvalue.
NOTE
IfcurrentCHboilertemperatureislowerthancurrentwatertanktemperature,DHWpumpwillnotbe
activatedtopreventthewaterinthetankfromcoolingdown.
Summermode
InthismodeonlyDHWpumpisactive(enabledwhenthepumpswitch‐onthresholdisreached)andtheCH
valvesareclosedinordernottoheatthehouseunnecessarily.IftheCHboilertemperatureistoohigh(when
returnprotectionfunctionisenabled),thevalvewillbeopeninanemergencyprocedure.
4.3.8 Fuelselection
MAIN
MENU
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FUEL
SELECTION
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Pellet
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Wood
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Automatictransition
Thisfunctionisusedtoselectthetypeoffuelused‐pelletorwood.Dependingonuser’schoice,certain
factorysettingschange.
Automatictransition
Thisfunctioninvolvesautomaticfuelchange.IftheCHboilerisfiredwithwood,oncethewoodhasbeenburnt
up,itispossibletochangethefueltypeintopelletwithoutthenecessityofusingFire‐upfunction.Whenthe
CHboilerisinoperationmodeandCHsensordetectsthatthetemperatureislowerthanthepre‐setthreshold,
thecontrollerwillemptythegrateandstartpelletfireup,afterthetimedefinedinWaitingtimefunction.
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