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No C wire "smart" thermostat
- Thread starter Neggy
- Start date
Terry D
Well-known member
You either need to run a new 5 conductor stat wire or a lot of smart stats now come with something that installs down on the furnace to make it work. I believe ecobee is one. I think a nest will work without a c wire
Last edited:
oldwino
ALLIANCE MEMBER
Terry is correct. The Nest doesn’t require a C wire
rlitman
Well-known member
Their part will add a c-wire to a three wire system, so it may work for the OP, but it wouldn't work for me, because it cannot be used on a two wire system. There are "add a c wire" kits for two wire systems, but I found it better to just run a new wire.ecobee has a wiring diagram and a small piece that installs at the furnace end to eliminate the c wire
Oh, and if you have an Ecobee, there's an alternative unsupported option. Put the Ecobee at the boiler, and put the remote sensor at your "thermostat" location. The Ecobee can be set to control based on external sensors alone, ignoring it's internal sensors.
As an example, my upstairs heat zone has the staircase in the middle of the house, and the best (furthest from an outside wall and most central) thermostat location is in the hallway, at the top of the stairs. This works fine most of the time, but on really cold evenings, the heat from the downstairs zone would rise up the stairs and warm the thermostat, causing the upstairs bedrooms around it to get chilly.
With an Ecobee, I have sensors in each bedroom, and use their average to control the zone, ignoring the hallway internal sensor.
Plus the two wires are just for power. You can mount a 24 volt transformer anywhere and power the thermostat. The Prestige communicates wirelessly to a equipment interface module, EIM the the thermostat wires from the HVAC equipment connect too. It does require a Redlink Internet Gateway to connect to the home's internet. Great thermostat, I have one.Honeywell Prestige has every (HVAC) feature under the sun and only uses 2 wires. wifi features are optional.
I started with one, now I have two, and a few of my friends have 3 - all are happy with them. minimum heat setpoint is 40F, so it's good for garages, too.Plus the two wires are just for power. You can mount a 24 volt transformer anywhere and power the thermostat. The Prestige communicates wirelessly to a equipment interface module, EIM the the thermostat wires from the HVAC equipment connect too. It does require a Redlink Internet Gateway to connect to the home's internet. Great thermostat, I have one.
I have a Redlink TH8000 in the garage. A Prestige was a bit overkill!
It is great to turn up the heat, or turn down the AC before I get home so the shop is Comfy when I get there. For the garage I have only an unoccupied schedule, set for 55 degrees heat and 80 degrees cooling. When I head out there I override the temp for the time I plan on being in the shop and the temp goes back to the unoccupied setting on it's own. No need to set the temp back.
It is great to turn up the heat, or turn down the AC before I get home so the shop is Comfy when I get there. For the garage I have only an unoccupied schedule, set for 55 degrees heat and 80 degrees cooling. When I head out there I override the temp for the time I plan on being in the shop and the temp goes back to the unoccupied setting on it's own. No need to set the temp back.