York SUNLINE MagnaDRY DR180C/E00 Technical Manual

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York SUNLINE MagnaDRY DR180C/E00 Technical Manual Manual pdf 16 page image

036-21539-003-B-030516 Unitary Products Group• Electric Heat Operation - All electric heat models (fac-tory installed only) are wired for a single power sourceand include a bank of nickel chromium elementsmounted at the discharge of the supply air blower to pro-vide a high velocity and uniform distribution of air acrossthe heating elements. Every element is fully protectedagainst excessive current and temperature by fuses andtwo thermal limit switches.The power supply wiring can be routed into the controlbox through a threaded pipe connection in the base panof the unit or through a knockout in the wiring panel onthe front of the unit.• BAS Controls - York’s Magnum series units offer factorymounted BAS controls such as Novar, Honeywell,Johnson, and CPC.REHEAT MODE SEQUENCE OF OPERATIONThe reheat control board allows the user to select two differ-ent modes of operation via a jumper connection on the board.(See Figure 2.) Each mode is described below. Refer to Fig-ures 2 - 4 when reading this section.“NORMAL” MODEWhen the reheat control board (RCB) detects a needfor dehumidification (24VAC) at "HUM" via the fieldsupplied dehumidistat connected to RHTB-1 andRHTB-2 and there is not a call for cooling, it energizesthe hot gas relay (HGR), which energizes the 3-wayvalve (SOL 3), the condenser coil valve (SOL 2), andde-energizes the reheat coil bleed valve (SOL 1). TheY1 signal is passed to the unit control board (UCB),which engages circuit # 1, resulting in circuit #1 reheatmode operation.When the room thermostat calls for first stage cooling,with or without a call for dehumidification, the RCBsenses a signal through "Y1", de-energizing the HGR,which de-energizes SOL 3 and SOL 2, and energizesSOL 1, engaging circuit # 1, resulting in circuit #1 cool-ing mode operation.When the room thermostat calls for second stage cool-ing, the RCB senses a signal through "Y1" & "Y2" andengages circuit #1 and circuit #2 in the cooling mode.Indoor blower operation is initiated upon a call for firststage cooling, second stage cooling or dehumidification.Anytime there is a call for 2 stages of cooling, the unitwill not operate in the reheat mode, even if there is acall for dehumidification at "HUM".The unit will not operate in the reheat mode if there isany call for heating.On units with economizers, the unit will not operate inthe reheat mode if there is a call for cooling and theeconomizer is operating as first stage of cooling.All safety devices function as previously described.FIGURE 1 - UNIT CUTAWAY