Code: SEQ73003
Price: $1,304.68
Quantity in Basket: None
Manufacturer: Johnson Controls

Category: Electrical Controls

S-7300 Circulating Pump Sequencer

The Johnson Controls S-7300 Circulating Pump Sequencer* is an automatic electric switching device designed to automatically activate a “standby” circulating pump whenever the operating pump fails. By cutting in the standby unit, the S-7300 provides added protection against potential damages from coil freeze-ups, equipment overload strain and other such related problems. The S-7300 employs a solidstate time delay relay and low voltage control circuitry. It is housed in a sturdy, surface mounted cabinet, with knockouts on the top and bottom. The face plate has a “Lead Pump” manual selector switch, a “Reset” button, and green “Flow-Normal” and red lead pump “Failure” pilot lights mounted on it. Both pilot lights have a “Press-to-Test” feature.

The Sequencer is also equipped for the addition of an outdoor air thermostat. The thermostat will open the circuit on a rise in temperature, stopping the operating pump. Operation is automatically resumed when the temperature drops down below the set point.

In a circulating pump application two circulating pumps are ordinarily used in the water line: a lead or main operating pump and a standby or backup pump. The “Lead Pump” manual selector switch is placed in either the “P-1” or “P-2” position for selection of the lead pump. The green pilot light indicates a “Flow-Normal” condition whenever either pump P-1 or P-2 is operating. If the lead pump should fail, the SPDT pressure differential or flow switch alerts the sequencer and energizes its time delay relay, turning off the green “Flow-Normal” pilot light. If the flow is interrupted for more than thirty seconds, the time delay relay will
simultaneously deenergize the lead pump, energize the standby pump, activate the red “Lead Pump Failure” pilot light, and trigger the optional alarm, if included.

*The S-7300 Circulating Pump Sequencer was tested under Underwriters Laboratories, Inc. Standard 873, Temperature Indication and Regulating Equipment, and is U.L. listed (Guide XAPX, File E27734). When normal flow has been restored, the green “Flow- Normal” pilot light will be activated, indicating both a return to normal flow conditions, and that the standby pump has replaced the lead pump. After the cause of the interruption has been eliminated, by repairing or replacing the lead pump, the “Reset” button must be depressed to reestablish the initial lead-standby sequence and turn off the red “Lead Pump Failure” pilot light. The continuous indication of thegreen“Flow-Normal” pilot light again indicates lead pump operation. The “Lead-Pump” manual selector switch can be placed in either the “P-1” or “P-2” position. In case of lead pump “Failure”, the sequencer will always index to the standby pump, P-2 or P-1, no matter which pump is selected as the lead pump, P-
or P-2. In the event of power failure, the sequencer will immediately start the lead pump when power is restored. If the lead pump has failed, the standby pump will begin operating after the 30 second flow interruption.


The Johnson Controls S-7300
Circulating Pump Sequencer
may be mounted in any position
on a flat, relatively smooth
surface, with four #10 screws.


The S-7300 Sequencer is
provided with line voltage and
relay connections in the top of
the cabinet. A low voltage seven
station terminal strip is located in
the bottom of the cabinet. The
S-7300 U.L. approved wiring
barriers are assembled to permit
line voltage wiring to enter
through the top and low voltage
wiring to enter through the
bottom, remove barrier No. 1;
when low voltage must be routed
through the top, remove barrier
No. 2. Whenever both barriers
are removed, all wires must
have a 600 volt insulation rating.
All wiring must be in accordance
with applicable national and
local electrical codes.

Replaces Part Numbers: S-7300-3, CARS-7300-3