I am wiring a second thermostat right next to the original one. The new needs a C wire. Can I share it from the old one?
Old: 8 wires, used to run heat pump (w/ heating and AC) and backup oil. Now only runs AC from heat pump on occasional summer day.
New: Has 2 wires run to it. Controls instant on hot water heater for radiant system.
The new thermostat says, "WILL NOT OPERATE WITHOUT WIRE TO 'C'". Can I take the C wire from the existing thermostat and bridge it to the new thermostat? Can two thermostats share this C wire?
According to Can I piggyback a thermostat with a C Wire hookup on a furnace? I think the answer is "Yes", but when I try it, the new thermostat does not have power.