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

Contents

Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 87 page image

87Table 58 — Humidity ConfigurationTable 59 — Related Humidity PointsDehumidification and Reheat — The Dehumidifi-cation function will override comfort condition set points basedon dry bulb temperature and deliver cooler air to the space inorder to satisfy a humidity set point at the space or return airhumidity sensor. The Reheat function will energize a suitableheating system concurrent with dehumidification sequenceshould the dehumidification operation result in excessive cool-ing of the space condition.The dehumidification sequence requires the installation of aspace or return air humidity sensor or a discrete switch input. ACEM (option or accessory) is required to accommodate an RH(relative humidity) sensor connection. Reheat is also possibleusing a heat reclaim coil (field-supplied and installed) or a hotgas reheat coil (special order, factory-installed). Reheat is notpossible with electric heat or gas heat.Dehumidification and reheat control are allowed duringCooling and Vent modes in the occupied period.On constant volume units using thermostat inputs (C.TYP =3), the discrete switch input must be used as the dehumidifica-tion control input. The commercial Thermidistat device is therecommended accessory device.SETTING UP THE SYSTEM — The settings for dehumidi-fication can be found at the local display at Configura-tionIAQ DEHU.Dehumidification Configuration (D.SEL) — The dehumidi-fication configuration can be set for the following settings:• D.SEL = 0 — No dehumidification and reheat.• D.SEL = 1 — The control will perform both dehumidifi-cation and reheat with modulating valve (hydronic).• D.SEL = 2 — The control will perform dehumidificationand reheat with staged gas only.• D.SEL = 3 — The control will perform both dehumidifi-cation and reheat with third party heat via an alarm relay.In the case of D.SEL=3, during dehumidification, thealarm relay will close to convey the need for reheat. Atypical application might be to energize a 3-way valve toperform hot gas reheat.• D.SEL = 4 — The control will use the Humidi-MiZer®adaptive dehumidification system.• D.SEL = 5 — The control will perform both dehumidifi-cation and reheat with third party heat reclaim via theheat reclaim output. The heat reclaim output (H.SEL)must be configured before D.SEL.Dehumidification Sensor (D.SEN) — The sensor can be con-figured for the following settings:• D.SEN = 1 — Initiated by return air relative humiditysensor.• D.SEN = 2 — Initiated by space relative humidity sensor.• D.SEN = 3 — Initiated by discrete input.Economizer Disable in Dehum Mode (D.EC.D) — Thisconfiguration determines economizer operation during Dehu-midification mode.• D.EC.D = YES — Economizer disabled during dehu-midification (default).• D.EC.D = NO — Economizer not disabled during dehu-midification.Vent Reheat Set Point Select (D.V.CF) — This configurationdetermines how the vent reheat set point is selected.• D.V.CF = 0 — Reheat follows an offset subtracted fromreturn air temperature (D.V.RA).• D.V.CF = 1 — Reheat follows a dehumidification heatset point (D.V.HT).Vent Reheat RAT Offset (D.V.RA) — Set point offset usedonly during the vent mode. The air will be reheated to return-air temperature less this offset.Vent Reheat Set Point (D.V.HT) — Set point used only dur-ing the vent mode. The air will be reheated to this set point.Dehumidify Cool Set Point (D.C.SP) — This is the dehu-midification cooling set point.Dehumidity RH Set Point (D.RH.S) — This is the dehumidi-fication relative humidity trip point.Heat Reclaim Configuration (H.SEL) — This is the heat re-claim configuration.• H.SEL = 0 (NONE) — Heat reclaim is not performed.• H.SEL = 1 (RELAY) — The control will perform bothdehumidification and reheat with third party heat via aheat reclaim relay on the SCB board. In the case ofD.SEL=5, during dehumidification, the heat reclaimrelay will close to convey the need for "re-heat" need. Atypical application might be to energize a 3-way valve toperform hot gas reheat.• H.SEL = 2 (MODULATING) — The control will per-form both dehumidification and reheat with modulatingvalve (hydronic).ITEM EXPANSION RANGE UNITS CCN POINT DEFAULTHUMD HUMIDITY CONFIGURATIONHM.CF Humidifier Control Cfg. 0 - 4 HUMD_CFG 0HM.SP Humidifier Setpoint 0 - 100 % HUSP 40H.PID HUMIDIFIER PID CONFIGSHM.TM Humidifier PID Run Rate 10 - 120 sec HUMDRATE 30HM.P Humidifier Prop. Gain 0 - 5 HUMID_PG 1HM.I Humidifier Integral Gain 0 - 5 HUMID_IG 0.3HM.D Humidifier Deriv. Gain 0 - 5 HUMID_DG 0.3ACT.C HUMIDIFIER ACTUATOR CFGSSN.1 Humd Serial Number 1 0 - 9999 HUMD_SN1 0SN.2 Humd Serial Number 2 0 - 6 HUMD_SN2 0SN.3 Humd Serial Number 3 0 - 9999 HUMD_SN3 0SN.4 Humd Serial Number 4 0 - 254 HUMD_SN4 0C.A.LM Humd Ctrl Angle Lo Limit 0-90 HUMDCALM 85ITEM EXPANSION UNITS CCN POINT WRITE STATUSConfigUNITSENSSRH.S Space Air RH Sensor SPRHSENSConfigUNITSENSRRH.S Return Air RH Sensor RARHSENSConfigUNITSENSMRH.S Mixed Air RH Sensor MARHSENSInputsREL.HRA.RH Return Air Rel. Humidity % RARH forcibleInputsREL.HSP.RH Space Relative Humidity % SPRH forcibleInputsREL.HMA.RH Mixed Air Relative Humidity % MARH forcibleOutputsACTUHMD.P Humidifier Act.Curr.Pos. % HUMDRPOSOutputsACTUHMD.C Humidifier Command Pos. % HUMDCPOSOutputsGEN.OHUM.R Humidifier Relay HUMIDRLY