What happens if you wire a 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.

What happens if you wire a 2 wire thermostat wrong?





If you get it wrong, the heat will run continuously. Once you have them paired, attach one pair to “24VAC” (R) and the other to “Heat call” (W) on the thermostat. Doesn’t matter which one, since the thermostat just shorts them either way.

How do I know if I installed my thermostat correctly?

How to test if the thermostat is properly installed?

  1. Step 1 – Turn off HVAC power. …
  2. Step 2 – Remove the thermostat cover. …
  3. Step 3 – Remove wires from terminals. …
  4. Step 4 – Turn HVAC power back on. …
  5. Step 5 – Test other wires. …
  6. The display. …
  7. Incorrect temperature. …
  8. Strange behavior.

What should thermostat wiring look like?

Thermostat Wiring Tips



If your thermostat controls your heat, you will have a white wire. The Y wire is yellow and connects to your air conditioning compressor. The G wire is green and connects to the fan. Rc and Rh: The red wire(s) are the power source for your thermostat.

What color wire goes where on a thermostat?

This is the most typical thermostat wiring style, and it applies to systems that regulate both heat and air conditioning. The wires are typically arranged as follows: red for 24-volt hot, white for heat, yellow for cooling, green for the fan, and blue for common (although the common wire may be a different color).

How are thermostats wired?





The most basic thermostat has 2 wires; usually a red and a white wire. Two wire thermostat wiring is used for furnaces only and usually doesn’t need a “C” or “Common” wire. That’s why we only need two wires: Red wire for power (24h).

How do you wire a thermostat with 2 wires?

Quote from the video:
Quote from Youtube video: One on the top. And there's one on the bottom. It's gonna allow us to remove the plate from the wall. And then we have our two wires our black wire and our white wire in my case.

How do you wire a 2 wire thermostat for heat?

Strip the red and white wires back about 1/4 inch at both the thermostat and the furnace ends. Connect the white wire to the “W” terminal on the furnace and thermostat. Repeat this for the red wire, connecting it to the “R” terminal on both the furnace and thermostat.

How do you check thermostat wire continuity?

Quote from the video:
Quote from Youtube video: So set your gesture to continuity. With these two wires wiring out in together. At the thermostat. Test them those wires are fine now that we've established that the red and black wires are okay.

What is the black thermostat wire?



Common Terminal

This the Common Terminal, and usually, a blue or black wire is run to the transformer from this terminal to complete the circuit, and in some cases, provide power to the Thermostat. This terminal is found on thermostats designed to work with Heating Pumps and is used to power the defrost cycle on the heat pumps.

Is RC wire same as C wire?

No the Rc is the red wire. You need 5 wires or more for this to run with all the functions. You can use one of the other wires but you have to drop control of the fan. It will only come on when furnace comes on.

Does R wire go to RH or RC?



An R wire can go into a Nest Learning Thermostat’s Rc or Rh connector.

Can I connect C wire to R?

If the black wire on the R terminal goes to the thermostat and only the thermostat, you can safely move it over to the C terminal. The AC and humidistat being hooked up to C is correct. R and C together carry the 24v power that a smart thermostat (and some programmable models) use for power.

Do I use R or RC on thermostat?

In a thermostat, the R wire is responsible for powering the entire HVAC system (through a transformer). If you have both an Rh (Red-heat for powering the heating) and an Rc (Red-cool for powering the cooling), then the R wire can be connected to either Rh or Rc.

Do I need a jumper from R to RC?

If you just have one wire, regardless if it’s labeled RC, it will go into the R terminal, and the jumper connecting terminals R and RC will be in place. Some thermostats have a jumper switch, some have a metal staple, others may have a plug, and the jumper may also just be a wire connecting the two terminals.

What does RH and RC stand for on a thermostat?



RC: The RC terminal is the 24-volt cooling power supply. RH: The RH terminal is the 24-volt heating power supply. (Note: The RC and RH terminals are jumpered together in a four-wire heat/cool system and a single-stage heat pump system but not in a five-wire heating/cooling system.)

What is the difference between RH and RC thermostat wires?

There is no standard for the colour of the RH wire, but most units use a red one. The RC wire, on the other hand, refers to “red cooling”. It’s the same with the RH wire in that it powers the thermostat. For the RC, it powers the cooling system.

What color is C wire?

Blue wires

Blue wires are also called “C” wires because they are the Common wire. C wires are necessary for any “smart” thermostat that needs to be connected to a power source 24/7, regardless of your heat pump type.

Where does Rh wire go on thermostat?



The Rh wire connects to your heating system as opposed to your cooling system. This wire may be red without an H attached to it, depending on if you have a dual transformer setup. The Rh wire connects to the RH terminal on your thermostat.