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Tech Tip #10
Remote Relay Unit
The Remote Relay Unit (RRU) is used at remote locations when it is desirable
to control several large loads such as second service panels, hot tubs,
electric furnaces or electric boilers by simply running low-voltage wire
loads to the remote location instead of trying to work with high-voltage,
high-current wires.
The RRU contains:
- Four double-pole, single-throw (DPST) relays.
- Relay coil wiring harnesses (one for each relay), and
- Relay coil wiring harnesses (for connecting remote relays to the controller
board).
Note: RRUs are available with one to eight relays. The unit shown
below is standard.

Click on image for a close-up view
Hook-up
1. Install the RRU at the desired location.
2. Run low-voltage wire from the control unit location to the location
of the RRU. Use the same number of conductors as wires in the wire harness
of the remote unit, two per relay.
3. Wire-nut the low-voltage wires to the remote unit wire harness. Be
sure to write down the wire color matchups.
4. Wire to the contacts of the relays, just as you would if you were
wiring the control unit. You may need to refer to the particular unit's
installation manual or its appropriate Tech Tip to be sure this is correct.
Always follow NEC and/or local codes.
5. Attach the other end of the low-voltage wires to the harnesses supplied
for attaching to the contoller's logic board. See the diagram.
6. Remove the cover from the controller's logic card to make it easier
to attach the plugs to the logic board's output jacks. Plug each remote
relay's plug into the desired control point jack on the controller's logic
board.
7. Connect the wires to the logic card as shown in the diagram.
a) You may move the relays already connected to the controller to other
positions, or you may disconnect them as required to achieve the desired
control point position.
b) The diagram shows one such hookup. Obviously, many combinations are
available. See the table below for some possible combinations.
Caution
Do not common any relay wires together.
Switching Order
The Energy Sentry® RRU uses four DPST relays with an 8-wire harness
(two for each relay). These wires are tied into the main control unit via
an 8-conductor, 18-gauge wire that connects to the control point output
jacks on the logic board with the connectors provided. The switching order
depends on the priority programmed for each auxiliary relay.
Remote Relay Unit:
Example of Priority Hookups
Electric Furnace or Electric Boiler
|
Last
Shed |
24-hour control |
First Shed |
| Relay |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
| Load |
Dryer |
Optional
(A/C)
5KW
Heat |
Water
Heater |
5KW
Heat |
5-10KW
Heat |
5-10KW
Heat |
|
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Heat Pump with Individual Element Control
|
Last
Shed |
24-hour control |
First Shed |
| Relay |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
| Load |
Dryer |
H.P.
Compressor |
Water
Heater |
5KW
Heat |
5KW
Heat |
5KW
Heat |
5KW
Heat |
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