3.10.2.1 Load pumps
The 120VAC power supply to the load pumps (P/V1, P/V2, P/V3, and P/V4) is factory installed
and connected to P/V-L and P/V-N for your convenience. If you use the P/V relay connections
for zone valves, you need to remove and cap off the 120VAC connections at P/V-L and P/V-N.
The 24VAC can then be applied using an external transformer to supply power to zone valves.
The upper 4 pairs of contacts on the connector strip are then powered to manage up to 4 load
pumps – the top pair for Load 1, the second pair for #2 etc. Once the controller is programmed
for the respective loads, the boiler manages all the loads without need of further relays (for
loads up to ⅓ HP; for more – use a protective relay).
3.10.2.2 Boiler pump
The boiler (primary) pump is powered by the yellow wire from the pair labeled "Boiler Pump".
Wire the pump's neutral to the white wire labeled "AC In". Do not attempt to connect the boiler
pump to the pump/zone valve terminal block along the controller’s right edge as this is reserved
for the secondary pumps and/or zone valves only.
Figure 37 Electrical box with boiler pump relay
- black and yellow wires - EX 400, EX 500
Figure 38 Electrical box with boiler pump relay
- black and yellow wires - EX 700, EX 850
Power in - black wire.
To boiler - yellow wire.
If the total boiler amperage drawn is less than 12 amps and the boiler pump is 120V, you can
connect the black wire from the relay to the line voltage mains supplied to the boiler. For 120
volt boiler pumps, the black wire can be connected to the line voltage mains and the yellow wire
connected to boiler pump. For 208/240 volt boiler pumps, the black wire can be one leg of the
208/240 voltage mains and the yellow wire connected to the boiler pump.
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