Carrier WEATHERMASTER 48/50Z030-105 Operation And Service Manual

Also see for 48/50Z030-105: Installation instructions

Contents

Carrier WEATHERMASTER 48/50Z030-105 Operation And Service Manual Manual pdf 65 page image

65Table 55 — Dirty Filter Switch PointsMonitoring of the filter status switch is disabled in theService Test mode and when the supply fan is not commandedon. If the fan is on and the unit is not in a test mode and thefilter status switch reads “dirty” for 2 continuous minutes, analert is generated. Recovery from this alert is done through aclearing of all alarms or after cleaning the filter and the switchreads “clean” for 30 seconds.NOTE: The filter switch should be adjusted to allow for theoperating cfm and the type of filter. Refer to the accessoryinstallation instructions for information on adjusting the switch.Economizer — The economizer control is used to managethe outside and return air dampers of the unit to provide venti-lation air as well as free cooling based on several configurationoptions. This section contains a description of the economizerand its ability to provide free cooling. See the section on indoorair quality for more information on setting up and using theeconomizer to perform demand controlled ventilation (DCV).See the Third Party Control section for a description on how totake over the operation of the economizer through externalcontrol.The economizer system also permits this unit to performsmoke control functions based on external control switchinputs. Refer to the Smoke Control Modes section for detaileddiscussions.Economizer control can be based on automatic controlalgorithms using unit-based set points and sensor inputs. Thiseconomizer control system can also be managed through exter-nal logic systems.The economizer system is a factory-installed option. Thisoption includes a factory-installed enthalpy control device todetermine the changeover condition that permits free coolingoperation. This unit can also have the following devicesinstalled to enhance economizer control:• Outside air humidity sensor• Return air humidity sensor• Outside airflow controlNOTE: All these options require the controls expansion mod-ule (CEM).The Z Series economizer damper is managed by a commu-nicating actuator motor(s) over the unit’s Local EquipmentNetwork (LEN). This provides the ability of the control systemto monitor, diagnose and report the health and operation of theactuator and damper system to the local display and CCNnetwork, thus providing extensive diagnostic tools to servicers.SETTING UP THE SYSTEM — The economizer configura-tion options are under the Local Display Mode Configuration→ECON. See Table 56.Economizer Installed? (EC.EN) — If an economizer is notinstalled or is to be completely disabled the configurationoption EC.EN may be set to No. Otherwise in the case of an in-stalled economizer, this option must be set to Yes.Economizer Actuator 2 Installed? (EC2.E) — For 48/50Z055-105 units, a second economizer actuator is required. For sizes055-105, set this configuration to Yes.Economizer Minimum Position (EC.MN) — The configura-tion option EC.MN is the economizer minimum position. Seethe section on indoor air quality for further information on howto reset the economizer further to gain energy savings and tomore carefully monitor IAQ problems.Economizer Maximum Position (EC.MX) — The upper lim-it of the economizer may be limited by setting EC.MX. It de-faults to 98% to avoid problems associated with slight changesin the economizer damper’s end stop over time. Typically thiswill not need to be adjusted.Economizer Trim for Sum Z? (E.TRM) — Sum Z is theadaptive cooling control algorithm used for multiple stagesof mechanical cooling capacity. The configuration option,E.TRM is typically set to Yes, and allows the economizer tomodulate to the same control point (Sum Z) that is used tocontrol capacity staging. The advantage is lower compressorcycling coupled with tighter temperature control. Setting thisoption to No will cause the economizer, if it is able to providefree cooling, to open to the Economizer Max. Position(EC.MX) during mechanical cooling.ECONOMIZER OPERATION — There are four potentialelements which are considered concurrently which determinewhether the economizer is able to provide free cooling:1. Dry bulb changeover (outside-air temperature qualification)2. Enthalpy switch (discrete control input monitoring)3. Economizer changeover select (E.SEL economizerchangeover select configuration option)4. Outdoor dewpoint limit check (requires an installed out-door relative humidity sensor installed)Dry Bulb Changeover — Outside-air temperature may beviewed under Temperatures→AIR.T→OAT. The controlconstantly compares its outside-air temperature reading againstthe high temperature OAT lockout (OAT.L). If the temperaturereads above OAT.L, the economizer will not be allowed to per-form free cooling.NOTE: If the user wishes to disable the enthalpy switch fromrunning concurrently, a field-supplied jumper must be installedbetween TB201 terminals 3 and 4.Enthalpy Switch — The state of the enthalpy switch can beviewed under Inputs→GEN.I→ENTH. Enthalpy switches areinstalled as standard on all Z Series rooftops. When the switchreads high, free cooling will be disallowed.The enthalpy switch opens (reads high) when the outdoorenthalpy is above 24 Btu/lb or dry bulb temperature is above70 F and will close when the outdoor enthalpy is below23 Btu/lb or the dry bulb temperature is below 69.5 F.NOTE: The enthalpy switch has both a low and a high output.To use this switch as designed the control must be connected tothe low output. Additionally there is a switch logic setting forthe enthalpy switch under Configuration→SW.LG→ENT.L.This setting must be configured to closed (CLSE) to work prop-erly when connected to the low output of the enthalpy switch.There are two jumpers under the cover of the enthalpyswitch. One jumper determines the mode of the enthalpyswitch/receiver. The other is not used. For the enthalpy switch,the factory setting is M1 and should not need to be changed. SeeFig. 8 for a diagram showing the settings on the enthalpy switch.ITEM EXPANSION RANGE CCNPOINTConfiguration→UNIT→SENS→FLT.S FilterStat.Sw.Enabled ? Enable/Disable FLTS_ENAInputs→GEN.I→FLT.S Filter Status Input DRTY/CLN FLTSM3M2M1OFF100%50%0%Fig. 8 — Enthalpy Switch Jumper Positions