I installed a new thermostat to a 3 wire system (replaced an old mercury thermostat) I labeled the wires according to the terminal label on the old thermostat and hooked them up accordingly. Now my boiler valve doesn't turn off when the thermostat is satisfied... but if I nudge the little valve wheel it closes. My plumber thought it was a lazy valve and we replaced it, but the action is the same... Is it possible my wiring is incorrect?