I'm replacing my old thermostat with a honeywell

The Honeywell RTH2300 doesn't need a C-wire. See the documentation in the Installation & Setup section on the support page: https://www.honeywellhome.com/us/en/support/air/thermostats/programmable-thermostats/5-2-day-programmable-thermostat-w-change-reminder-rth2300b1038-e1/ . If your old thermostat had a C-wire, check the system board at the furnace. Make sure that the G-wire (usually green) at the thermostat is also connected to the system board's G-wire connection.

First check the obvious: what is the current position of the fan switch? It should be on auto. (That's the switch on the right.)

Is the temperature that the thermostat is reading match the real temperature in the room? Check with a thermometer. If the area near the thermostat is still above (cooling) or below (heating) the set temperature, the room circulation could be a factor. I know my home's thermostat keeps the A/C running for a while after a thermometer on the other side of the living room reaches the desired temperature in the evening when parts of the house are closed off.

If the thermostat temperature reading is correct, the signal may not be reaching the system board. You can check that all of the individual wires between the thermostat and the system control board are undamaged. I've seen those thin wires break when you take them off one thermostat and connect them to another.

Another possibility is that a relay isn't working. Contact Honeywell if the temperature sensor isn't giving the correct reading. Contact a heating and cooling repair person if the problem is with a relay or the system board.

I hope this helps.

Cindy Wells

where do the wires currently land?

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The Orange wire for the reversing valve and used with a Heat Pump
If you have a heat pump, then yes. If you have a gas furnace then no. If you have a HP and the reversing valve is not connected, then you might just be using the emergency electric heat strips. :-o

That is something that someone needs to lay eyes on. You never know how one will color code the wires @ the furnace...let alone through the wall. Someone will have to ohm out the wires.

I have only seen one Honeywell thermostat that would work with a 3-wire heating system.

I would replace it with a White-Rodgers 1F80-0471. They are about $100, but they are a good thermostat, and they work well with the 3-wire zone valves.

Most other thermostats have the "Y" terminal that you need, but do not control the zone valve correctly.

Helping Hands Services
- Fairbanks, Alaska -

yep- 1 wire to R the othe to W (or W1) dosent mater which is which

Check the other end of the wire to see how it's connected.

your old thermostat is a milivolt and the wire runs from the heater to the thermostat. You have to open the back of the new one and connect the wire as per the instructions on the wireing diagram that came with the new one. I just installed a similar one myself, you will be very happy with it.

You need to go into the installer setting to change it from heatpump to single stage gas heat.Go to www.honeywell.com if youve lost them.