If we put it simply, a 2 wire thermostat is one which has only 2 wires coming out of its backside. When it comes to low voltage systems, a 2 wire thermostat is usually known as a “heat only thermostat” and is used for systems like a gas furnace (with only heating option).

Can I use a smart thermostat with 2 wires?

The Nest Thermostat is compatible with 2 wire low voltage HVAC systems that are either heat only systems or cooling only systems.

How do you test a 2 wire thermostat?

Remove the jumper wire between the R and W terminal. Connect the two wires that you disconnected in step 3 back to the R and W terminals, and make note of what color wire is connected to which terminal. Connect the two wires back to your thermostats R and W terminals. Check that the colors match.

What happens if you wire a 2 wire thermostat wrong?

Potential consequences of improper installation could include: Electric shock. Blowing a circuit breaker. Damaging the thermostat unit, the electrical system or even the AC/furnace unit itself.

Does a thermostat need a neutral?

In all cases, the thermostats is a simple switch, connecting a switched output to live when heat is required. Where the thermostat contains an accelerator heater or electronics, a neutral connection is also required.

Does Nest thermostat work without C wire?

The Nest thermostat contains a rechargeable lithium ion battery. In a system with a C-wire, the Nest charges itself from the C-wires current and all is fine. In a system without a C-wire, though, Nest recharges its battery when the heating or cooling runs.