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I'm working on a customers Weil Mclain boiler model CG-6-PIDN series 12 BTU 175,000 Honeywell thermostats #T87F. There are two zones for this split level home, they have two air handlers, one for the 1st floor and one for the 2nd floor which I have killed the power to at this point to isolate my issue. If you have one stat calling for heat and the other off I read 50 volts at the stats red and white wires, when you turn on the second stat so both zones are calling for heat you have 24 volts, this is the same if I take the reading at either stat. There are two zones each zone has its own Honeywell RA89A 1074 switching relay, I attached a diagram of the wiring that I traced out. I disconnected all the wires to verify voltage for both relays and the boiler transformer and each one is 24 volts on there own. I cant seem to figure out why I'm getting 50 volts in this situation and I don't understand why the system is wired the way it is with the two relays that have 24 volts transformers to energize the coil to pull in the relays that turn on the 120 volts to start the circulating pumps when they also are in the loop with the boilers 24 volt transformer. The R 24 volt red wire coming from the boilers transformer splits off and goes to the thermostats RH terminals, the G white wire coming from the boilers transformer splits up and goes to the two switching relays T terminals which also would have there own 24 volts and the W white wires from each thermostat goes back to the switching relays other T terminals which is the line side of the 24 volts. There are no zone valves in this set up just ball valves to isolate the zones for repairs. Can anyone help me on this to correct the issue the customer wants to have me install two Nest thermostats but I told him the 50 volt issue would need to be corrected first.