I'm trying to install a 2nd generation Nest thermostat for my hydronic floors. So it's only meant for heating and not for cooling.

Someone else removed the old thermostat a long time ago so I don't know what the setup used to be.

I see three wires: Red, Green, White. (Red-White shows 30V AC.)

I'm thinking: Red -> Rh Green -> G White -> C

Does that sound right?

Many thanks in advance!

  • Does your system use two-wire or three-wire zone valves, or circulator zoning for that matter? Can you show us photos of where these three wires connect? – ThreePhaseEel Nov 10 '17 at 1:48
  • The de-facto standard is R (Red) for 24V, W (White) for heat, G (Green) for Fan. Is there a circulation fan somewhere? – Stavr00 Nov 10 '17 at 20:10

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