Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for WeatherExpert 48N2: Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

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Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 86 page image

86When the outdoor air cfm sensor is enabled, the EconomizerMin.Position (ConfigurationIAQDCV.CEC.MN) andthe IAQ Demand Vent Min.Pos (ConfigurationIAQDCV.CIAQ.M) will no longer be used. During vent periods,the control will modulate the damper to maintain the outdoorair intake quantity between O.C.MX and O.C.MN. The indoorair quality algorithm will vary the cfm between these twovalues depending on ConfigurationIAQAQ.SPDAQ.Land the ConfigurationIAQAQ.SPDAQ.H set pointsand upon the relationship between the IAQ and the outdoor airquality (OAQ).The economizer’s OA CFM Minimum Position Deadband(O.C.DB) is the deadband range around the outdoor cfmcontrol point at where the damper control will stop, indicatingthe control point has been reached. See the Economizer sectionfor more information.Humidification — The N Series ComfortLink controlscan control a field-supplied and installed humidifier device.The ComfortLink controls provide two types of humidificationcontrol: A discrete stage control (via a relay contact) and a pro-portional control type (communicating to a LEN actuator). Thediscrete stage control is used to control a single-stage humidifi-er, (typically a spray pump). The proportional control type istypically used to control a proportional steam valve serving asteam grid humidifier.The ComfortLink controls must be equipped with a controlsexpansion module and an accessory space or return air relativehumidity sensor.If a humidifier using a proportional steam valve is selected,the Carrier actuator (Carrier Part No. HF23BJ050) must beadapted to the humidifier manufacturer’s steam valve. ContactBelimo Aircontrols for information on actuator linkage adapterpackages required to mount the actuator on the specific brandand type of steam valve mounted by the humidifiermanufacturer.The actuator address must be programmed into the Com-fortLink unit’s humidifier actuator serial number variables.SETTING UP THE SYSTEM — These humidity configura-tion are located in the local displays under ConfigurationHUMD. See Table 58. Related points are shown in Table 59.Humidifier Control Configuration (HM.CF) — The humidi-fier control can be set to the following configurations:• HM.CF = 0 — No humidity control.• HM.CF = 1 — Discrete control based on space relativehumidity.• HM.CF = 2 — Discrete control based on return air rela-tive humidity.• HM.CF = 3 — Analog control based on space relativehumidity.• HM.CF = 4 — Analog control based on return air rela-tive humidity.Humidity Control Set Point (HM.SP) — The humidity con-trol set point has a range of 0 to 100%.Humidifier PID Run Rate (HM.TM) — This is the PID runtime rate.Humidifier Proportional Gain (HM.P) — This configurationis the PID Proportional Gain.Humidifier Integral Gain (HM.I) — This configuration is thePID Integral Gain.Humidifier Derivative Gain (HM.D) — This configuration isthe PID Derivative Gain.OPERATION — For operation, PID control will be utilized.The process will run at the rate defined by the ConfigurationHUMDH.PIDHM.TM. The first part of humiditycontrol tests the humidity control configuration and will turnon corresponding configurations to read space or return air rel-ative humidity. If the supply fan has been ON for 30 secondsand the space is occupied, then the humidification is started.Actuator Control — Control is performed with a generic PIDloop where:Error = HM.SP – humidity sensor value (SP.RH or RA.RH,depending on configuration).The PID terms are calculated as follows:P = K * HM.P * errorI = K * HM.I * error + “I” last time throughD = K * HM.D * (error – error last time through)Where K = HM.TM/60 to normalize the effect of changing therun time rateRelay Output Control — If the humidity sensor reading isgreater than the humidity set point then the humidity relay(OutputsGEN.OHUM.R) is closed. The relay will openwhen the humidity is 2% less than the humidity set point.CONFIGURING THE HUMIDIFIER ACTUATOR —Every actuator used in the N Series control system has its ownunique serial number. The rooftop control uses this serialnumber to communicate with the actuator. The actuator serialnumber is located on a two-part sticker affixed to the side of theactuator housing. Remove one of the actuator’s serial numberlabels and paste it onto the actuator serial number records labellocated inside the left-hand access panel at the unit’s controlpanel. Four individual numbers make up this serial number.Program the serial number of the actuator in its Humidifier Ac-tuator Configurations group, ACT.C (SN.1, SN.2, SN.3, SN.4).NOTE: The serial numbers for all actuators can be foundinside the control doors of the unit as well as on the actuatoritself. If an actuator is replaced in the field, it is a good idea toremove the additional peel-off serial number sticker on theactuator and cover up the old one inside the control doors.Control Angle Alarm (ConfigurationHUMDACTCC.A.LM) — The humidifier actuator learns what its end stopsare through a calibration at the factory. Field-installed actuatorsmay be calibrated in the Service Test mode. When an actuatorlearns its end stops through calibration, it determines its controlangle. The actuator will resolve this control angle and expressits operation in a percent (%) of this learned range.If the humidifier actuator has not learned a sufficient controlangle during calibration, the actuator will be unable to controlhumidity. For this reason, the humidifier actuator has a config-urable control angle alarm low limit (C.A.LM). If the controlangle learned through calibration is less than C.A.LM, an alertwill occur and the actuator will not function.NOTE: This configuration does not typically need adjustment.It is configurable for the small number of jobs which mayrequire a custom solution or workaround.