EWC Controls Forum

Great, thanks for your clarification!

Eric thanks for your quick response. It seems from the documentation that the B needs to be 24V when heating is on, O needs to be 24V when cooling is on. Would it work if I bridge "W" and "B" for heat and "Y" and "O" for cool?
Erwin

I have installed the new Honeywell RTH9580WF as my zone 1 thermostat, to replace a Robertshaw 9610. I had to run a C-wire from the board and disconnect "B" and "O" (there is no terminal for those on the RTH9580WF). The controller works great in zone 1 but for zone 2 does not open anymore.
If the ...