Carrier AQUASNAP 30RA/RH Operation & Maintenance Instructions Manual

Carrier AQUASNAP 30RA/RH Operation & Maintenance Instructions Manual Manual pdf 31 page image

315.3 - Evaporator water pump controlThe unit can control one or two evaporator water pumps. Theevaporator water pump is turned on when this option isconfigured (see User configuration) and when the unit is in oneof the on modes described above or in delay mode. Since theminimum value for the delay at start-up is 1 minute(configurable between 1 and 15 minutes), the pump will runfor at least one minute before the first compressor starts. Thepump is kept running for 20 seconds after the unit goes to stopmode. The pump keeps working when the unit switches fromheating to cooling mode or vice-versa. It is turned off if theunit is shut down due to an alarm unless the fault is a frostprotection error. The pump can be started in particularoperating conditions when the evaporator heater is active (seesection 5.5). See section 5.14 for the particular evaporatorpump control for the follower unit (master/slave assembly).If two pumps are controlled and the reversing function hasbeen selected (see User 1 configuration), the control tries tolimit the pump run time delta to the configured pump change-over delay. If this delay has elapsed, the pump reversingfunction is activated, when the unit is running. During thereversing function both pumps run together for two seconds.If a pump has failed and a secondary pump is available, theunit is stopped and started again with this pump.The control provides a means to automatically start the pumpeach day at 14.00 hours for 2 seconds when the unit is off. Ifthe unit is fitted with two pumps, the first pump is started onodd days and the second pump is started on even days. Startingthe pump periodically for few seconds increases the life-timeof the pump bearings and the tightness of the pump seal.ON/OFFSTATUSOffOnOnOnOnOnOnOnOnOnOnOnOnOnOnOnCONTROLTYPE-LocalLocalLocalLocalLocalRemoteRemoteRemoteRemoteRemoteCCNCCNCCNCCNCCNHEATING/COOLINGSELECTION INLOCAL MODE-CoolingHeatingAutoAutoAuto----------REMOTE HEATING/COOLING CONTACTS------Cooling modeHeating modeAuto modeAuto modeAuto mode-----HC_SEL-----------CoolingHeatingAutoAutoAutoOUTDOOR TEMPERATURE---> Cooling threshold< Heating thresholdBetween cooling and heating thresholds--> Cooling threshold< Heating thresholdBetween cooling and heating thresholds--> Cooling threshold< Heating thresholdBetween cooling and heating thresholdsOPERATINGMODECoolingCoolingHeatingCoolingHeating*StandbyCoolingHeatingCoolingHeating*StandbyCoolingHeatingCoolingHeating*StandbyPARAMETER STATUS5.4 - Control interlock contactThis contact checks the status of a loop (water flow switch andcustomer safety loop, see section 3.6). It prevents the unit fromstarting if it is open when the delay at start-up has expired. Thisopen contact leads to an alarm shut-down, if the unit isrunning.5.5 - Evaporator antifreeze protectionThe heater for the evaporator and water pump cycling (for unitswith a pump) can be energised to protect the evaporator, if itcan be damaged by freezing, when the unit is shut down for along time at low outdoor temperature.NOTE: Evaporator heater control parameters can bemodified, using the Service configuration.5.6 - Control pointThe control point represents the water temperature that the unitmust produce. The inlet water is controlled by default, but theoutlet water can also be controlled (requires a Serviceconfiguration modification).Control point = active setpoint + reset5.6.1 - Active setpointTwo setpoints can be selected as active in cooling mode andthree in heating mode. Usually, the second cooling setpoint isused for unoccupied periods or for ice storage (brine unit). Thesecond setpoint in heating mode is used for unoccupiedperiods, and the third heating setpoint is used for holidayperiods or public holidays. Depending on the current opera-tions, the active setpoint can be selected by choosing the itemin the Information menu, with the user’s volt-free contacts,with network commands or with the setpoint timer program(schedule 2).* Does not apply to cooling only units that do not control a boiler.