Honeywell RTH6360 Wiring: R-Switch, Heat Pump O/B and C Wire

1. What the RTH6360 works with

The RTH6360 is Honeywell Home’s battery-powered 5-2 day programmable thermostat, sold in stores under part numbers such as RTH6360D1002 and RTH6360D1017. Resideo’s RTH6360 Series Quick Installation Guide (33-00201EF-11) is the source for everything below. Its System Setup menu allows:

• Conventional forced air (gas, oil, electric or hot water fan coil): up to 2 heat stages and 2 cool stages.
• Heat pump (air to air): 1 compressor stage, plus at most 1 stage of auxiliary or emergency heat.
• Radiant heat (hot water or steam boiler), and cool only.

It does not work on line voltage. The guide’s check: if the old thermostat has thick black wires with wire nuts, or is marked 120 V or higher, stop. Our line voltage thermostat guide covers what to buy instead. A heat pump with a two-stage compressor is also beyond this model; the Honeywell T6 Pro handles that.

2. The terminals

The RTH6360 mounts on the UWP wall plate, which Honeywell shares across several models, so not every terminal is live. From the guide:

The plate also has a K terminal, and the guide’s wire checklist has a line for it, but the guide gives no wiring instructions for K on this model. If the old thermostat has a wire on a terminal that is not in the table, the guide says you need additional wiring support and sends you to Honeywell Home support before going further.

A wire on L or L/A is a heat pump fault signal; the guide says this model does not support the fault alert and to ask a contractor about a replacement model if you want it. Our L, S and T terminals page explains what those wires do.

3. The R-switch and jumpers

Older thermostats often have a small metal staple or a short wire joining R to Rc. The guide says to remove any jumper and not to count it as a wire: “The RTH6360 thermostat does not need jumpers.” The R-switch on the wall plate replaces it.

• One R wire (it was on R, Rh or Rc): set the R-switch up and put the wire in the R terminal. The guide also allows an Rc wire to go into Rc with the switch up.
• Two R wires (R or Rh, and Rc): set the R-switch down, put the Rc wire in Rc and the R or Rh wire in R.
• Old thermostat had both R and RH (conventional systems): switch down, the R wire goes to Rc and the RH wire goes to R.

Two R wires mean two transformers, one for heating and one for cooling. Our Rh and Rc page shows how to tell which you have.

4. Batteries and the C wire

This is where the RTH6360 differs from most thermostats on the UWP plate. The guide’s wiring notes say: “C does not power the thermostat display or operations; batteries are always required.” Two AA alkaline batteries go in the back of the thermostat before you snap it onto the plate.

So a missing C wire is not a problem for this model, and adding one will not let you skip the batteries. The guide’s rules for C wires you already have:

• One C or C1 wire: connect it to C.
• Two C or C1 wires: wrap each one separately with electrical tape and do not connect them.

Replace the batteries when the low battery icon appears (about two months of warning), or once a year. If new batteries go in within two minutes, the time and day are kept; the other settings are stored permanently. If you are choosing between this and a Wi-Fi model, note that Wi-Fi thermostats such as the Honeywell RTH6580WF do need a C wire. Our C terminal page explains why.

5. Wiring steps

1. Turn off power at the breaker or the furnace switch. To confirm, set the old thermostat to call for heat or cooling; if nothing starts within 5 minutes, the power is off.
2. Pull off the old faceplate and check for thick wires with wire nuts (line voltage). If you see them, stop.
3. Photograph the wiring with the terminal letters visible.
4. Remove any jumpers, then note which of R, Rh and Rc have wires.
5. Label each wire with the letter of its terminal as you disconnect it. Go by the letter, not the colour; our wire colour guide explains why colours cannot be trusted.
6. Mount the UWP plate: pull the wires through, level it, mark and drill (7/32 in bit for red anchors, 3/16 in for yellow), and leave at least 1/4 inch of bare copper on each wire.
7. Set the R-switch and insert the R wire or wires (section 3).
8. Insert the other wires, one per terminal, into the inner holes while pressing the tab. Tug each one gently. Compare the result with your photo.
9. Fasten the plate with all three screws and close its door.
10. Fit the two AA batteries, snap the thermostat on, and turn the power back on.
11. Set the date and time, then go through System Setup (section 7).

A typical gas furnace with air conditioning ends up with R (switch up), W, Y and G, plus C if the cable has one. A two-stage furnace adds W2; a two-stage air conditioner adds Y2.

6. Heat pump wiring

For a heat pump, the guide matches each labelled wire to the same letter: R, C, Y for the compressor, G for the fan, O/B for the reversing valve, and AUX or E for backup heat. Its notes for heat pumps are stricter than for furnaces:

• Keep the R-switch up (one R wire).
• Do not use W. The guide: “Do NOT use W for heat pump applications. Auxiliary heat must wire to AUX or E.” A backup heat wire labelled W, W1 or W2 on the old thermostat goes to AUX.
• Separate O and B wires: put the O wire on O/B and attach the B wire to the C terminal. If another wire is already on C, the guide says to stop and contact a qualified contractor.
• Both V and VR wires, or Y1, W1 and W2 wires together: stop and contact a qualified contractor.
• No fault alert: the L/A terminal is not supported, so a wire from L is taped off.

The B-to-C rule surprises people. When a thermostat has both O and B wires, the B wire is usually the transformer common, not a reversing valve wire, which is why it lands on C. Our B terminal page covers the different meanings of B. For the difference between AUX and E, see the aux vs emergency heat guide and the heat pump with emergency heat diagram.

7. System Setup after wiring

On a new installation the thermostat walks through System Setup after the clock. To return to it later, press and hold Menu and + for about 5 seconds, then press Select. Use + or - to change a value and Select to save and move on; “Done” appears at the end. The options that depend on your wiring:

Option 205 matters more than it looks: it is the setting the guide points to when the fan does not run during heating. The Em Heat mode is offered only for heat pumps with auxiliary heat, so set option 221 to 1 backup stage when AUX or E is wired.

8. If something runs wrong

The guide’s troubleshooting table ties most faults to a setup option, not to a wire:

• Display is blank: fit fresh AA alkaline batteries the right way round.
• Cannot switch to Cool: option 220 must be 1 or 2.
• Fan does not run when heat is on: check option 205 matches your heating equipment.
• Heat pump blows cool air in heat mode, or warm air in cool mode: check options 200 and 218. O and B are opposites.
• “Heat On” or “Cool On” flashing: compressor protection. Wait 5 minutes.
• Nothing responds: check the mode and set point, the breaker, the furnace power switch and the furnace door, then wait 5 minutes.

If the equipment still does nothing, our thermostat troubleshooting checklist covers blown fuses and dead transformers, and the multimeter guide shows how to check for 24 V between R and C. Honeywell Home’s support site has current contact options. For another battery-powered Honeywell, see our Honeywell RTH2300 wiring guide; for the contractor version on the same wall plate, the Honeywell T4 Pro wiring guide.

9. Frequently asked questions