Carrier 48/50AJ Static Pressure Reset Related Points, Fan Status Monitoring Configuration

Table 76 — Static Pressure Reset Related Points

	ITEM	EXPANSION	RANGE	UNITS	CCN POINT	DEFAULT
Inputs
→ 4-20	→ SP.M	Static Pressure mA	4-20	mA	SP_MA
→ 4-20	→ SP.M.T	Static Pressure mA Trim	-2.0 - +2.0	mA	SPMATRIM
→ 4-20	→SP.R.M	Static Pressure Reset mA	4-20	mA	SPRST_MA	0.0
→ RSET →SP.RS		Static Pressure Reset	0.0-3.0	in. wg	SPRESET	0.0
Outputs
→ Fans → S.VFD		Supply Fan VFD Speed	0-100	%	SFAN_VFD

Table 77 — Fan Status Monitoring Configuration

ITEM	EXPANSION	RANGE	CCN POINT
SFS.S	Fan Fail Shuts Down Unit	Yes/No	SFS_SHUT
SFS.M	Fan Stat Monitoring Type	0 - 2	SFS_MON

Fan Stat Monitoring Type (SFS.M) — This configuration se- lects the type of fan status monitoring to be performed.

0 - NONE — No switch or monitoring

1 - SWITCH — Use of the fan status switch

2 - SP RISE — Monitoring of the supply duct pressure.

Fan Fail Shuts Down Unit (SFS.S) — This configuration will configure the unit to shut down on a supply fan status fail or simply alert the condition and continue to run. When config- ured to YES, the control will shut down the unit if supply fan status monitoring fails and the control will also send out an alarm. If set to NO, the control will not shut down the unit if supply fan status monitoring fails but will send out an alert.

SUPPLY FAN STATUS MONITORING LOGIC — Regard- less of whether the user is monitoring a discrete switch or is monitoring static pressure, the timing for both methods are the same and rely upon the configuration of static pressure control. The configuration that determines static pressure control is Configuration→SP→SP.CF. If this configuration is set to 0 (none), a fan failure condition must wait 60 continuous seconds before taking action. If this configuration is 1 (VFD), a fan fail- ure condition must wait 3 continuous minutes before taking action.

If the unit is configured to monitor a fan status switch (SFS.M = 1), and if the supply fan commanded state does not match the supply fan status switch for 3 continuous minutes, then a fan status failure has occurred.

If the unit is configured for supply duct pressure monitoring (SFS.M = 2), then

•If the supply fan is requested ON and the static pressure reading is not greater than 0.2 in. wg for 3 continuous minutes, a fan failure has occurred.

•If the supply fan is requested OFF and the static pressure reading is not less than 0.2 in. wg for 3 continuous min- utes, a fan failure has occurred.

Dirty Filter Switch — The unit can be equipped with a field-installed accessory dirty filter switch. The switch is located in the filter section. If a dirty filter switch is not installed, the switch input is configured to read “clean” all the time.

To enable the sensor for dirty filter monitoring set Configuration→UNIT→SENS→FLT.S to ENABLE. The state of the filter status switch can be read at Inputs→GEN.I→ FLT.S. See Table 78.

Table 78 — Dirty Filter Switch Points

ITEM	EXPANSION	RANGE	CCN
			POINT
Configuration→UNIT	Filter	Enable/	FLTS_ENA
→SENS→FLT.S	Stat.Sw.Enabled ?	Disable
Inputs→GEN.I	Filter Status Input	DRTY/CLN	FLTS
→FLT.S

Monitoring of the filter status switch is disabled in the Service Test mode and when the supply fan is not commanded on. If the fan is on and the unit is not in a test mode and the filter status switch reads “dirty” for 2 continuous minutes, an alert is generated. Recovery from this alert is done through a clearing of all alarms or after cleaning the filter and the switch reads “clean” for 30 seconds.

NOTE: The filter switch should be adjusted to allow for the operating cfm and the type of filter. Refer to the accessory installation instructions for information on adjusting the switch.

Economizer — The economizer control is used to manage the outside and return air dampers of the unit to provide venti- lation air as well as free cooling based on several configuration options. This section contains a description of the economizer and its ability to provide free cooling. See the section on Indoor Air Quality Control on page 67 for more information on setting up and using the economizer to perform demand controlled ventilation (DCV). See the Third Party Control section for a description on how to take over the operation of the economiz- er through external control.

The economizer system also permits this unit to perform smoke control functions based on external control switch inputs. Refer to the Smoke Control Modes section for detailed discussions.

Economizer control can be based on automatic control algorithms using unit-based set points and sensor inputs. This economizer control system can also be managed through exter- nal logic systems.

The economizer system is a factory-installed option. This unit can also have the following devices installed to enhance economizer control:

•Outside air humidity sensor

•Return air humidity sensor

NOTE: All these options require the controls expansion mod- ule (CEM).

SETTING UP THE SYSTEM — The economizer configura- tion options are under the Local Display Mode Configuration →ECON. See Table 79.

Economizer Installed? (EC.EN) — If an economizer is not installed or is to be completely disabled then the configuration option EC.EN should be set to No. Otherwise in the case of an installed economizer, this value must be set to Yes.

Economizer Minimum Position (EC.MN) — The configura- tion option EC.MN is the economizer minimum position. See the section on indoor air quality for further information on how to reset the economizer further to gain energy savings and to more carefully monitor IAQ problems.

Economizer Maximum Position (EC.MX) — The upper lim- it of the economizer may be limited by setting EC.MX. This value defaults to 98% to avoid problems associated with slight changes in the economizer damper’s end stop over time. Typi- cally this will not need to be adjusted.

Economizer Trim for Sum Z? (E.TRM) — Sum Z is the adaptive cooling control algorithm used for multiple stages of mechanical cooling capacity. The configuration option, E.TRM is typically set to Yes, and allows the economizer to

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