Installation Operation Maintenance

OperationEconomizer Set-UpAdjusting the minimum positionpotentiometer located on the uniteconomizer Actuator (ECA) sets therequired amount of ventilation air.Two of the three methods fordetermining the suitability of theoutside air can be selected utilizingthe enthalpy potentiometer on theECA, as described below:1. Ambient Temperature -controlling the economizingcycle by sensing the outside airdry bulb temperature. The Tablebelow lists the selectable drybulb values by potentiometersetting.2. Reference Enthalpy - controllingthe economizer cycle by sensingthe outdoor air humidity. TheTable below lists the selectableenthalpy values bypotentiometer setting.If the outside air enthalpy valueis less than the selected value,the economizer is allowed tooperate.3. Comparative Enthalpy - Byutilizing a humidity sensor and atemperature sensor in both thereturn air stream and theoutdoor air stream, the unitcontrol processor (RTRM) will beable to establish whichconditions are best suited formaintaining the zonetemperature, i.e. indoorconditions or outdoor conditions.The potentiometer located onthe ECA is non-functional whenboth the temperature andhumidity sensors are installed.Table 52 - Potentiometer SettingPotentiometer Dry BuIb EnthalpySetting (°C) (KJ/kg)A 23* 63B 21 58C 19 53D 17 51*Factory SettingReliaTel Control HeatingOperationWhen the system switch is set tothe "Heat" position and the zonetemperature falls below the heatingsetpoint controlband, a heat cycle isinitiated when the RTRMcommunicates ignition informationto the Ignition module (IGN).Ignition ModuleTwo Stage (IGN) runs self-check(including verification that the gasvalve is de-energized). (IGN) checksthe high-limit switches (TC01 &TC02) for normally closed contacts.With 115 VAC power supplied to theignition module (IGN), the hotsurface ignition probe (IP) ispreheated for approximately45 seconds. The gas valve (GV) isenergized for approximately7 seconds for trial for ignition, toignite the burner.Once the burner is ignited, the hotsurface ignition probe (IP) is deenergizedby the ignition module(IGN) and functions as the flamesensing device.If the burner fails to ignite, theignition module will make two moreattempts before locking out. Thegreen LED will indicate a lock out bytwo fast flashes. An ignition lockoutcan be reset by:1. Opening for 3 seconds andclosing the main powerdisconnect switch2. By switching the "Mode" switchon the zone sensor to "OFF" andthen to the desired position3. Allowing the ignition controlmodule to reset automaticallyafter one hour.58RT-SVX20B-E4