enter image description here Old thermostat had a jumper between RH And RC, iam replacing that with a Honeywell Programmable thermostat, but idk if I should replace this jumper on new ther mostat ? And if so, should I remove Metal jumper (already in place) on new thermostat? No clue what I’m doing

  • 1
    What model is your new 'stat? – ThreePhaseEel Oct 24 '17 at 1:37
  • What do the directions for the new thermostat say? – mmathis Oct 24 '17 at 14:31

RH & RC are jumpered at the factory because most systems have only one transformer whether that is heating or cooling or both. If this is the case with your system, leave the jumper in place. If you have a heating system combined with a cooling system and if both of those systems have their own transformer or if you have any two different system controlled by one thermostat and they have separate transformers then and only then do you pull the jumper.


If you have forced air heat, then you'll likely leave the jumper in place. If you have radiant heat, you might have separate transformers. However, since the jumper is currently in place, you'll almost certainly want to leave have it on the new thermostat.

Further reading

Rc is the terminal that connects to one leg of the control transformer, from the cooling system. Rh is similar, though connects to one leg of the heating system. If your system only has a single control transformer (typical in forced air systems), you'll only have one R wire coming to the thermostat. Since there's only one R wire, you'll need a jumper to get power to both Rc and Rh.

If your system has two separate control transformers, you'll have two R wires coming to the thermostat. In this case, you'll remove the jumper and connect the R wires to their respective terminals.

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