York PREDATOR MagnaDRY DR090 Technical Manual

Also see for PREDATOR MagnaDRY DR090: Installation manual Installation manual

Contents

246721-YTG-C-0606Unitary Products Group 9• Power Exhaust - This accessory installs in the unit witha down flow economizer. Power exhaust plugs into theconnector in the unit bulkhead. You must purchase1EH0408 barometric relief when applying to a hori-zontal flow application.• Manual Outdoor Air Damper - Like the motorized out-door air damper, each manual outdoor air damperincludes a slide-in damper assembly with an outdoor airhood and filters. Customers have a choice of damperswith ranges of 0% to 100% or 0% to 35% outdoor air entry.• Motorized Outdoor Air Damper - The motorized out-door air damper includes a slide-in/plug-in damperassembly with an outdoor air hood and filters. The out-door air dampers open to the preset position when theindoor fan motor is energized. The damper has a rangeof 0% to 100% outdoor air entry. Factory installed optionor field installed accessory.• Smoke Detectors - The smoke detectors stop operationof the unit by interrupting power to the control board ifsmoke is detected within the air compartment.• CO2 Sensor - Senses CO2 levels and automaticallyoverrides the economizer when levels rise above thepreset limits.• Dirty Filter Switch - This kit includes a differential pres-sure switch that energizes the fault light on the unit ther-mostat, indicating that there is an abnormally highpressure drop across the filters.• Coil Guard - Field installed decorative wire coil guard.• Hail Guard - This kit includes a sloped hood which installsover the outside condenser coil and prevents damage tothe coil fins from hail strikes. Field installed accessory only.• Flue Exhaust Extension Kit - In locations with wind orweather conditions which may interfere with properexhausting of furnace combustion products, this kit canbe installed to prevent the flue exhaust from enteringnearby fresh air intakes.• -60°F Gas Heat Kit - For installations which require gasheat units to perform in low ambient temperatures, a gassection heating kit is available. This kit provides electricheat in the gas heat controls section to ensure the gasvalve and controls will continue to function properly atextremely low temperatures.• Gas Heat High Altitude Kit - This kit converts a gas heatunit to operate at high altitudes, 2,000 to 6,000 feet. Con-version kits are available for natural gas and propane.• Gas Heat Propane Conversion Kit - This kit converts agas-fired heater from natural gas to propane. It contains themain burner orifices and gas valve replacement springs.• Gas Piping Kit - Contains pipe nipples, fittings and gascock required for gas supply connection with externalshut off.• Electric Heaters - The electric heaters range from 9 kWto 54kW and are available in all the voltage options of thebase units. All heaters are dual staged. Cooling unitsinclude an adapter panel for easy installation of the elec-tric heaters. Necessary hardware and connectors areincluded with the heaters. All heaters are intended forsingle point power supply.• Low Limit / Compressor Lockout Kit1. Compressor Lockout (CLO): To prevent mechanical(compressorized) operation of the unit during coldoutdoor conditions where there is a risk of returningliquid refrigerant back to the compressors.2. Low Limit Control (LLC): To prevent the supply airfrom dropping below a specified setpoint by utilizingthe units first stage heating means when there is ademand for cooling during cold outside conditions.• Metal Frame Filter Kit - Metal frame with polyester filtermedium.• Permanent Filters - Permanent filters are available.• Roof Curbs - The roof curbs have insulated decks andare shipped disassembled The roof curbs are availablein 8” and 14” heights. For applications with security con-cerns, burglar bars are available for the duct openings ofthe roof curbs.• Roof Curb Transition - Single Piece Adapter (10” High) -Roof curbs for transitioning from Sunline™ units to Pred-ator® units. Fits 7.5 to 12.5 Sunline™ roof curbs only.• Burglar Bars - Mount in the supply and return openingsto prevent entry into the duct work.• Thermostat - The units are designed to operate with 24-volt electronic and electro-mechanical thermostats. Allunits (with or without an economizer) operate with two-stage heat/two-stage cool or two-stage cooling only ther-mostats, depending upon unit configuration.REHEAT MODE SEQUENCE OF OPERATIONThe reheat control board allows the user to select two differ-ent modes of operation via a jumper connection on theboard. (See Figure 3.) Each mode is described below. Referto Figures 3 - 5 when reading this section.“NORMAL” MODEWhen the reheat control board (RCB) detects a need fordehumidification (24VAC) at "HUM" via the field supplieddehumidistat connected to RHTB-1 and RHTB-2 and there isnot a call for cooling, it energizes the hot gas relay (HGR),which energizes the 3-way valve (SOL 3), the condenser coilvalve (SOL 2), and de-energizes the reheat coil bleed valve(SOL 1). (In the DR150, SOL 2 is only energized when thedischarge pressure in circuit #1 rises above 235 psig and de-energizes SOL 2 after the discharge pressure falls below 175psig. Both outdoor fans of circuit #1 in the DR150 also disen-gage to conserve energy.) The Y1 signal is passed to the unitcontrol board (UCB), which engages circuit # 1, resulting incircuit #1 reheat mode operation.When the room thermostat calls for first stage cooling, with orwithout a call for dehumidification, the RCB senses a signalthrough "Y1", de-energizing the HGR, which de-energizesSOL 3 and SOL 2 and energizes SOL 1, engaging circuit #1,resulting in circuit #1 cooling mode operation.