topic Re: Wiring help from honeywell to nest in Nest Thermostats

Wiring help from honeywell to nest

meelmol — Wed, 28 Feb 2024 20:13:30 GMT

Hi,

I want to install a nest and am looking for a sense check on wiring.

My current honeywell has a jumpercable connecting R and RC, one wire into Y, W/OB and G.

Am i correct to assume that on a nest I should convert this as follows

Jumper cable -> single cable into Rc

Y -> Y

W/OB -> OB (or should this be the W terminal?)

G -> G

Am slightly confused about the W/OB because the nest also has a W terminal in addition to the OB terminal.

Image here: https://imgur.com/a/ARaygEl

Thanks!

Re: Wiring help from honeywell to nest

Markjosephp — Fri, 08 Mar 2024 19:32:32 GMT

Hello meelmol,

It looks like you're on the right track with the Nest Thermostat installation, but let me help clarify the wiring for you.

For the jumper cable connecting R and RC on your thermostat, you're correct in combining them into a single cable into the Rc terminal on the Nest Thermostat.

As for the other connections, in most systems, W is used for heating, and OB is used for reversing valves in heat pump systems. If you're unsure and if your system is a heat pump, it's likely that you'll connect it to the OB terminal on the Nest Thermostat and follow the rest of the terminals.

Let me know if you need more help—I'm here to further check it for you.

Best regards,
Mark

Re: Wiring help from honeywell to nest

meelmol — Fri, 08 Mar 2024 19:35:36 GMT

Hi Mark,

Thanks so much. It's an old furnace and I don't have an outdoor unit for heating so I'm guessing I don't have a pump, in which case I assume I connect the wire to the W terminal.

Thanks,

Re: Wiring help from honeywell to nest

Markjosephp — Fri, 08 Mar 2024 19:54:41 GMT

Hi meelmol,

You're welcome! If you don't have an outdoor unit for heating and there's no heat pump, connecting the wire to the W terminal is a good assumption. This terminal typically controls the heating function in many systems.

Feel free to reply if you have more questions in mind.

Thanks,

Mark