Sequence of Operation
52 RTU Open
Functions 1 and 2 are configured identically. Neither input may work reliably and downstream control may be
affected, depending on the function duplicated. The alarm clears and normal control is restored when the
input function duplication is corrected.
High Space Relative Humidity - The RTU Open generates this alarm when the space humidity exceeds the
Alarm Configuration > High Space Humidity Alarm Limit setpoint for 10 minutes. This alarm is inhibited until
the RTU runs for 15 minutes to allow for system stabilization after startup.
Low Space Relative Humidity - The RTU Open generates this alarm when the space humidity falls below the
Alarm Configuration > Low Space Humidity Alarm Limit setpoint for 5 minutes. This alarm is inhibited until
the RTU runs for 5 minutes to allow for system stabilization after startup.
High CO2 - The RTU Open generates this alarm when the space CO2 level exceeds the Alarm Configuration >
Occupied High CO2 Alarm Limit setpoint for 1-minute. This alarm will be inhibited until the RTU has been
running for 2-minutes to allow for system stabilization after startup.
Supply Fan Runtime - The RTU Open generates a this alarm when the accumulated runtime exceeds the Unit
Configuration > Supply Fan Service Alarm Timer value (when not set to 0). This alarm is most commonly
used to indicate an equipment maintenance interval is due. The supply fan runtime accumulator may be reset
by setting the
Maintenance > Reset Supply Fan Runtime Alarm to Clear, and then back to Run –
acknowledging each selection by clicking the
OK button when it appears. Setting Unit Configuration > Supply
Fan Service Timer value to 0 disables the supply fan runtime alarm function.
Compressor 1 Runtime - The RTU Open generates this alarm when the accumulated runtime exceeds the
Unit Configuration > Compressor 1 Service Alarm Timer value (when not set to 0). This alarm is most
commonly used to indicate an equipment maintenance interval is due. The
Compressor 1 Runtime
accumulator may be reset by setting the
Maintenance > Reset Comp 1 Runtime Alarm to Clear, and then
back to
Run – acknowledging each selection by clicking the OK button when it appears. Setting Unit
Configuration > Compressor 1 Service Timer value to 0 disables the Compressor 1 Runtime alarm function.
Compressor 2 Runtime - The RTU Open generates this alarm when the accumulated runtime exceeds the
Unit Configuration > Compressor 2 Service Alarm Timer value (when not set to 0). This alarm is most
commonly used to indicate an equipment maintenance interval is due. The Compressor 2 runtime
accumulator may be reset by setting the
Maintenance > Reset Comp 2 Runtime Alarm to Clear, and then
back to
Run – acknowledging each selection by clicking the OK button when it appears. Setting Unit
Configuration > Compressor 2 Service Timer value to 0 disables the Compressor 2 runtime alarm function.
Note that this function is unavailable if the
Service Configuration > Compressor States value is not set to Two
Stages.
Filter - The RTU Open generates this alarm when the accumulated runtime exceeds the Unit Configuration >
Filter Service Alarm Timer value (when not set to 0). This alarm is most commonly used to indicate a filter
replacement is due. Reset the filter service runtime accumulator by setting the
Maintenance > Reset Filter
Runtime Alarm to On, back to Off, and clicking the OK button after each setting. Setting Unit Configuration >
Filter Service Alarm Timer value to 0 disables the filter service alarm function.
Airside Linkage Alarm - An RTU Open may act as an air source in a zoned system. Carrier systems utilize a
function called Linkage™ to pass data between a master zone and its air source via an MS/TP network
connection. When the RTU Open is part of a linked system, it will indicate an airside linkage alarm if it loses
communications with its linkage master or if it receives invalid data.
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