No C Wire, No Problem

Emily Beierle November 18, 2019

Recently, a member of our program team had a Smart Thermostat installed. It was not a delightful process but ended happily for all, and we’d like to share the story.

The home is a 1967 vintage with a furnace only (two-wire) and a very old electromechanical thermostat which is likely original to the house . The HVAC contractor showed up, looked at the new Ecobee Smart Thermostat, looked at the existing wiring, and said, “I don’t install those units with the power adapters”.

Further discussion revealed that he’s had previous experiences with the adapters for use when a C wire isn’t present, and for him it was a 50/50 roll of the dice as to whether the adapter would work. As a businessperson, a 50/50 shot at satisfying the customer on the time which he’d based his quote wasn’t good enough and basically equated to a 50% chance he was going to lose money on the job and/or end up with an unhappy customer.

Our staffer still wanted a Smart Thermostat and looked at all the units with battery support. After reading a lot of reviews, the eventual product choice turned out to be the LUX GEO. Once installed, it was easy to download the app and get the thermostat connected into the home network. The app also has a battery setting that when set for “Optimized” should result in batteries lasting one year. Used without a C wire, it won’t connect to Alexa, but that wasn’t a deal breaker.

The unit went in easily, works perfectly, and no wiring was harmed in the process. The staffer is happy, and the staffers’s spouse is delighted to have an app to program the furnace and monitor the house temperature (and another building scientist is born).

Consider the LUX GEO when running a C wire just isn’t an option.

Download our Smart Thermostat List.

About the Author

Emily Beierle

Emily Beierle-O'Brien is a Program Management Associate at Build It Green and works closely with the Home Upgrade Program to ensure quality and accuracy within the program implementation. She is passionate about green building and sustainable living.

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