I am having trouble installing a new wireless thermostat to my existing Weil McLain boiler. My existing control wire utilized an Rh and W on the thermostat, but utilized the Y and G terminals on the boiler itself. The installation manuals indicate I need to connect a new C-Wire from the C terminal from the boiler to their c terminal on the thermostat and reconnect the other wires as is, but that doesn’t work. Do I need to relocate the wire on the Y terminal to the R terminal or am I missing something else? enter image description here

  • Is the LWCO allowing the boiler to fire? If the low-water cutoff has tripped, then the whole system will appear shut down because the thermostat terminals are downstream of the LWCO – ThreePhaseEel Feb 4 at 3:49
  • Or, in other words, can you measure 24VAC between G and C? – ThreePhaseEel Feb 4 at 4:21

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