Hack Your Nest Thermostat to Run a Gas Stove or Fireplace

If you, like me, heat your home exclusively with a gas fireplace or a free-standing gas stove, and you would like to control your system using a Nest thermostat, then this is the Instructable for you!

The only reason that the nest thermostat wont work on these types of systems is that they do not run enough voltage though their thermostat wires to power the Nest. So the trick is to power it another way.

First off, if you have an air conditioning system, then the Nest should be able to draw the power it wants from that and you should be good to go. If you do not, then you must trick the Nest into thinking that you do.

Just connect the thermostat wires as shown above and connect a 24 AC transformer (see next step) to provide the power. The positive lead from the transformer should go to the Rc terminal and the negative should go to the C terminal. In this way, you can trick the Nest into powering itself off of a transformer without putting any unwanted voltage over your thermostat wires.

These types of transformers are commonly available as sprinkler system components at your local hardware store.

I have been using this setup to reliably control my gas stove for over a year now with no issues, but of course, neither I nor Instructables can warranty your Nest or your stove, so hack at your own risk.

Happy Heating!

Step 1: 24 V AC Transformer

These are commonly available at your hardware store, usually in the sprinkler systems section and will provide the right voltage for your Nest.

I hid mine in the closet behind the wall where the thermostat lives and ran the wires through the wall for a clean setup.

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9 Discussions


3 months ago

I followed the steps and it works! The only weird thing is how much noise the relay makes... I can hear it all over my house. Any recommendations?


5 months ago on Step 1

Works on an Emerson Sensi T-55 too. There's a jumper on the back of the thermostat body that connects Rh with Rc. You want to clip that to electrically isolate the heating circuit from the 24 vac that runs the thermostat. Hook up Rc and C to a 24 volt power supply. You'll be running a new wire from the nearest outlet to the thermostat. Hook up Rh and W to your millivolt appliance. In my case it was a gas stove with simulated logs. You DO NOT WANT 24vac going to the gas valve of your appliance. I confirmed there was no voltage on the Rh/W circuit from the power supply. It simply closes when heat is called to complete the circuit in your appliance. Sensi doesn't specifically address running a millivolt system on their website but they do mention that jumper and how it will isolate the Rh/W circuit for "multiple transformer" systems.


2 years ago

I did this as well with a third generation nest and got voltage on the control wires. when I read another Hack they said I would need a 24 volt relay that when current is applied it is closed. Where would I get the relay and what type or model do I need to purchase? And yes, I hooked up the wires exactly like your diagram. Can you help please?


3 years ago

This worked great for me. I pulled out the multimeter and confirmed no voltage is applied to W1 and RH when in this configuration. Shipping back the relay I ordered just in case I saw 24v.


4 years ago

This is a really sweet hack. Now you just need to use IFTTT to automate your hack.

1 reply

4 years ago on Introduction

What if I told you Rc was intended to power the Thermostat? and Rh was to power the heating equipment? Thermostats have been designed this way from the first home systems.