Installation Operation Maintenance

OperationOperation with aconventional thermostatThe ReliaTel module hasconventional thermostatconnections as well as Zone SensorModule connections. When aconventional thermostat iscontrolling the unit, operationdiffers as follows:• Supply Air Tempering feature isnot available. If outdoor air isbeing introduced through theequipment, discharge airtemperature may be cold whennot actively heating.• Proportional Integral (PI) controlis not available.• Zone Sensor Diagnostics areonly available on the RTRMmodule on the J6 terminals,instead of at the Zone Sensor inthe space.• Intelligent Fall-Back is notavailable. If a failure occurs inthe device controlling theequipment, operation will cease.• Heat Pump Smart Recovery andSmart Staging is not available.Heat Pump operation becomesmore costly unless the genericcontrol being applied canaccomplish this.• Remote Sensing Capabilities arenot available on mostmechanical thermostats.• Space Temperature Averagingcapabilities are not available onmost mechanical thermostats.• 27½ to 50 VAV - Conventionalthermostat input terminals areinactive.• Built in Night Set Back andUnoccupied Functions functiondifferently with a conventionalmechanical thermostat.• A built-in algorithm which allowsfor automatic reset of thedischarge air temperature whileeconomizing is not available.The terminal strip for attaching thethermostat wires is located on theRTRM module in the controlcompartment.When the unit is operating from aconventional thermostat or otherbinary input, the economizersetpoint feature, relative to thecooling and heating setpoints, islost. The economizer control isbased strictly on a signal from thethermostat, but still maintainsmixed air temperature control of53°±3°F when in the economizermode. The economizer enable anddisable function is still determinedby the outside air sensor throughthe RTRM.If a single-stage thermostat is used,only the economizer (if enabled) orthe compressor (if economizer isdisabled) will operate on a call forcooling. A twostage thermostat isrequired to achieve economizeroperation and compressoroperation at the same time.With economizer enabled, a Y1 callfor 1st stage cooling will be theeconomizer. The damper willmodulate between minimumposition and 100% to maintainmixed air temperature at 53°±3°. At50°F the damper will be atminimum position. If theeconomizer is enabled, a Y2 call for2nd stage cooling will start the firstcompressor if required. If theeconomizer is disabled, 1st stage(Y1) will be the first compressor. Ifthe unit has two compressors, a callfor 2nd stage cooling (Y2) will startthe second compressor. When usinga conventional thermostat, or otherbinary input, the ReliaTel controlswill only allow two stages ofcooling.Figure 30 - Terminal stripCOMTX2Y2W2GW1/0Y1RCustomers occasionally requireoperation with a conventionalthermostat rather than a zonesensor. In some cases there is apreference for a specific thermostatmodel, and in others there isreluctance to adopt newertechnology that may not be as wellunderstood as conventionalthermostats. In addition, non-TraneBuilding Controllers typicallyprovide an interface to HVACequipment based on a conventionalthermostat interface. Units appliedwith this type of controller need toaccept conventional thermostatinputs.48RT-SVX20B-E4