Taco SR504 wiring for Indirect DHW

dvizz

I want to replace 3-24v relays that power 3 Taco circ. with the SR504. My question is how do I energize a relay mounted on the Weil Mclain board. The WM 24v circut is used to power the relay through the aquastat which powers a 3 way valve to send hot water flow from the boiler to the indirect, closing the flow to the baseboards. I want the SR504 to prioritize the Indirect and the way the system is wired now the baseboaed pumps will run even when flow is dirverted to the Indirect. I see the aquastat wiring going to the thermostst terminal #4 and the boiler TT wiring going to the end switch to prioritize the indirect operation.