How to Wire a home Heat/Cool thermostat
- 1). This guide will only cover wiring a typical five wire thermostat. If your home features a heat pump or dual stage heat your wiring will be slightly different from this procedure.
- 2). First things first, you will need to find the furnace on/off switch. Turn this switch off, this will cut power to your thermostat. Thermostats almost universally run off of 24V AC, although this isn't very dangerous you can cause harm to your equipment if the power is not off before beginning.
- 3
Before you remove your thermostat, make note of which colored wires go to which terminal. Common terminal labels are R,G,Y,W,C. There may be extra unused terminals and wires, that is perfectly okay. - 4). After you've removed your old thermostat you should have at least five wires. Red, Green, Yellow, White, and Common(which is usually blue)This coloring scheme is very commonly used. Red is your hot wire feeding the thermostat, Green is the control wire to your furnace's blower, Yellow is the control wire to your A/C unit, White is the control wire to your heat, and "C" also know as common (which is often blue),is the neutral of your 24V AC going to the thermostat. NOTE: Non digital thermostats often did not have a Common wire, if you are missing this wire, you may have to: add another wire, use an existing non-used wire, or some digital thermostats can function without them, read the documentation of your thermostat as different manufacturers deal with this differently.
- 5). At this point you will want to mount your thermostat per the manufacturers recommendations depending on what type of wall surface you have.
- 6
Although this wiring scheme is very common, yours may be different. The notes you made earlier will come in handy now. If your scheme matches the normal then hook each wire up to the matching terminal as such. If your scheme was different you will need to do some matching with your notes. - 7). Once you've wired everything and checked everything twice, you can go to your furnace and flip the switch, if you've done everything right your new digital thermostat should light up and just like that you're back in business.
