iWorx® PSU1
505-012, Effective: August 10, 2012 17
© 2012 Taco Electronic Solutions, Inc.
All operating modes that support standby failover normally switch off pumps that fail to satisfy the flow proof input. If
Flow Recovery is enabled both pump outputs will be energized after a 30 second delay. If modulated outputs are con-
figured, modulation levels are fixed to the minimum "On" level specified under the Pump Mod Set: On settings. Pump
runtime is not accumulated at any point in time while Flow Recovery is active.
Flow is monitored while the controller is operating in Flow Recovery mode. An automatic restart occurs during Flow
Recovery mode if automatic restarts are remaining and the controller detects flow for the amount of time specified by
the Flow Delay setting. The Restarts Left output value indicates the number of automatic restarts remaining. The num-
ber of automatic restarts is configurable under the Auto Recovery: Number Restarts setting. To prevent the controller
from restarting in Flow Recovery Mode, set Auto Recovery: Number Restarts setting to "0."
An automatic restart succeeds when a single pump is able to satisfy the flow proof sensor. Once an automatic restart
succeeds, a timer is started. The Restarts Left output value is restored to the Auto Recovery: Number Restarts setting
after one day of successful operation. Each automatic restart resets this timer to zero and another day of successful
operation must occur before the Restarts Left output value is restored.
While in Flow Recovery Mode, the Flow Recovery Mode output on the LCI displays "Yes".
When Flow Recovery Mode displays "Yes" and Restarts Left displays "0" the controller is in Flow Recovery mode, but
no longer able to attempt an automatic reset. Flow is not monitored. Since a successful automatic restart is required
before Restarts Left is restored, the controller operates in this state indefinitely until flow issues are resolved and a
manual controller reset is performed. Both outputs will be energized in accordance with demand inputs regardless of
the flow reading.
The controller will leave Flow Recovery Mode when an automatic restart occurs, the controller is manually reset, or
commissioning mode is used. While in Flow Recovery Mode, pump outputs are energized corresponding to the
demand input. Cycling demand causes controller outputs to turn on or off, but does not cause the controller to leave
Flow Recovery Mode.
The Pump Settings: Post Purge Time is enforced when demand input changes from active to inactive in Flow Recovery
mode. Both pump outputs are energized until the post purge time is complete.
In order to enable the Flow Recovery sequence, the following conditions must be met:
• Pump Settings: Operational Mode must be set to a mode other than "Single".
• Enable Alarm must be set to "Switch (Open)" for monitoring of a normally open flow switch or "Switch (Closed)" for
monitoring of a normally closed flow switch.
• Auto Recovery: Enable must be set to "On."
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