HVAC System Transformer
Most central HVAC systems have a common heating and cooling transformer. This is the factory default
setting for Jumper JP1. In some cases, you may have separate heating and cooling systems, each with their
own transformer. In that case, cut Jumper JP1 and wire the heating transformer red wire to the RH terminal
and the cooling system transformer red wire to the RC terminal. Wire the cooling system’s 24VAC Com to the
TZ43’s 24VAC Com terminal.