I'm not comfortable drawing up diagram, so maybe photos will help. My TH16 is wired for 120 volts.
From the TH16, L output (blue) and N neutral connect to the input side of the ONNO relay (GRN and BLU). This provides power to the relay.
NOTE: The TH16 has two N neutral terminals. One comes from the power source, the second goes to input side (GRN/BLU) of the OONO relay.
The two connections on the right side of the relay (SW1 and SW2) are dry (unpowered) and only open/close. Use the top SW1 terminals (NO normally open) to connect to the heater's fireman's switch.
The photo below (from
this Wiki page) shows the Pentair MasterTemp fireman's switch.
In this photo, the BLU/WTE terminated wires go the input side of the OONO relay:
View attachment 433662
This phots shows ORG/BLK off the OONO SW1 terminals to RED/WTE going to the fireman's switch via thermostat wire.
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