We recently moved into a house with an oil furnace that's about 40 years old, and central AC that's maybe 20 years old. We have a Honeywell thermostat that currently requires all 5 wires to get the oil furnace to kick on (looked like they might not all be in use/connected at the furnace) but currently works fine. The Honeywell thermostat uses battery power and has a yellow wire with a "K" label.
Trying to map over the wiring from the existing thermostat to the Nest Learning ends up reading as a "heat pump" which we do not have.
Thank you for taking the time in letting us know about your inquiry. I'd love to help.
Based on the wiring configuration, please move the blue wire from O/B to the C terminal and restart your thermostat after the changes.
Please note: turn off the power from your HVAC system at the breaker before touching the wires.
Please let me know how it goes.
I understand, and thanks for getting back to us. I appreciate your effort in taking these steps; let's sort this out.
Please note: turn off the power from your HVAC at the breaker before touching the wires.
Let me know if that helps.
Same issue persists, unfortunately. Cannot get hot air to come from the vents when testing the heat. The air coming from the vents is maybe 70F instead of +120F.
Now, the Nest reads my equipment as "heating, cooling, and fan" as opposed to thinking I had a heat pump like before, so that's an improvement at least. And the blue wire seems extraneous as it's not used in the prescribed reconfiguration and the nest appears to still be receiving power without it.
Hopefully that helps you further diagnose the issue. What should I try next?
Thanks for giving it a shot. Let's try another step:
Please keep me posted.
I'm sorry to hear the issue still persists. Thanks for giving it a shot; I appreciate it. We'd like to look into this further.
Please fill out this form with the needed information and let me know once you're done.