Most thermostats are 24 volt, while most pumps use 110 volts. You will need some type of relay to join these units together without a mess of wiring in between. So, even if you only have 1 zone, you will still need a switching relay to make the wiring easy, neat and clean to always know what is what.
Taco Switching Relays including the SR501-4 1 Zone Switching Relay can be found at www.supplyhouse.com
Taco Switching Relays including the SR501-4 1 Zone Switching Relay can be found at www.supplyhouse.com