Thermostat wiring

Furnace Thermostat Wiring and Troubleshooting

If you are looking for a better understanding of heat pump thermostat wiring, here is an example of a typical electronic type heat pump control wiring

The C-Wire, or “common wire” enables the continuous flow of 24 VAC power to the thermostat. It's a wire that (if you have one) runs all the way from your furnace to your thermostat. Questions about the C-wire are by far the biggest drivers of traffic to this site, so I've written this article to

The heat pump drives the compressor for both cooling and heating. Connecting a heat pump to an internal heating band will rejuvenate your heating and air

There is a high chance that the common wire is hiding behind the wall. Now lets check if you can install Honeywell WiFi thermostat without c wire.

The C wire, a.k.a. the "common wire", allows a constant flow of 24 VAC (volts AC) power to a smart thermostat. However, the C wire doesn’t provide the actual source of power to the thermostat. The wires that provide the source of power are the R wires (or hot wires). They are labeled Rh (for heating), Rc (for cooling), or Rh/c (for both heating and cooling). Some thermostats simply have one wire labeled R. The power from the R wire isn’t continuous and that is where the C wire comes in.

Magnetic Contactor Schematic Diagram

Single Element Electric Water Heater Thermostat Wiring Diagram. 120V, 230V and 240V AC Water Heater Connection and Installation. Heater Element Wiring.

Single Phase 240V and 230V Non-Continues Dual Element Water Heater Thermostat Wiring. 240V AC Non-Simultaneous Dual Element 5kW Water Heater Thermostat Wiring

If you’re replacing your thermostat, you might notice the wires are connected to different terminals, each of which denoted by a letter. Here’s what they mean.