All About Thermostats

All About Thermostats



Thermostats are great when they work and are confusing when they don’t. Often times they fail quietly, and other times they sound like a ticking time bomb (sans bomb). I replace thermostats pic__1with a brand I trust which is commercially used and that is the Pro1 line. This is my favorite thermostat because of the stability of the build, the reliability of its components, and its ease of use. It has an illuminated backlit display and is easy to program. More on this later.




Setting a Thermostat

Meanings of Letters and Jumpers

Image 2018-12-28 at 9.01.50 AM



Wiring a Thermostat

Some things to think about when wiring up a thermostat is to be sure which wires go where. What I mean is there are often two sets of wires for low-voltage that simultaneously carry 24 VAC through them. One set of wires goes to the doorbell most likely (that’s what that weird transformer sticking out of that electrical box is for) and another goes to your HVAC system. Somewhere along the line, people get these mixed up. You can use two transformer setups, but that is beyond the scope of this article and will only write an article on this upon special request.

For most people, there is already a thermostat hanging in the hallway and it is a simple matter of removing the old one (carefully) and replacing the new one. You would be surprised how many technically savvy people screw this one up because they are not paying attention. One implication of an improper install might be your house never heats up and or never cools down. Bad replace thermostat.


Chris’ install tips for installing a thermostat

Location considerations for a thermostat recommend that the thermostat not be installed in a location where direct sunlight from a window can hit it, behind a door, right above or below a vent (register) where it is directly being blown on. Do not install the thermostat on an outside facing wall, in corners, or anywhere where there could be a warm or cold pipe behind the thermostat. It should be easy to access and

Step one: De-energize Equipment

Power down all HVAC equipment, this means unplug or turn off the furnace or package unit. You can disable the power by turning off the HVAC breaker or going directly to the equipment disconnect near the unit.


Step two: Remove the Face

Pull the face off of the thermostat. This means grab the face with your little fingers and pull off the whole thermostat face. Don’t worry, it probably won’t break. And carefully set aside the face. NOTE: some thermostats are screwed in, make sure you are pulling on the right part or have lifted the right tab.pic__2

Don’t worry if what lies behind your thermostat doesn’t match mine. We will deal with that. Don’t panic if your wires are different colors, electricity doesn’t know what color the wire’s insulation is; as long as you know what each wire corresponds to, you’re good. Wire thermostat well, no need to wire thermostat again.

Note: Be sure to take a picture of how your old thermostat was wired in. Basically, this is all you have to do; wire the new one exactly like the old one. If you forgot this step, it’s a pretty good chance you messed this up and that’s why you’re here.


Step three: Remove Old Mounting Plate

Take your Precision Screwdriver and unscrew each wire. If they are all the same, take a piece of white electrical tape ( and mark what each wire is. i.e. R, W, G, Y etc. then take a #2 Philips screwdriver or an impact driver with a #2 bit on it  and remove the mounting plate of your old thermostat. Some thermostats have tabs, like Honeywell, and your just depress the tab and pull the wire out.



Step four: Mounting

Separate the new thermostat from its mounting plate and remove any hardware that came with it. You should have a mounting plate in your hand and some wires sticking out of the wall at this step. Take that plate and press it against the wall. Grab your Torpedo Level  and level the thermostat. Make sure it is upright. Take a pic__3pen and mark out the holes that you are going to use (use either the horizontal oriented holes (-) or the vertically oriented holed (|) don’t combine them. I like to use a small 5/32 drill bit  that goes on my impact driver and I drill out the holes I marked. Place the drywall anchors that came with the thermostat in and bang them with either your linemans or the butt of your gun. Screw in the mounting plate and level it. Sometimes buildings are built wonky and the floor isn’t level. In this case, try and match the thermostat with the building so that it “looks square”.


Step five: Wiring

Typically these wires should match the colors set forth on the mounting plate. Personally, I would go to each location where the wires are terminated (often inside the HVAC unit) and take a picture then match my thermostat to those wires. But for the lazier of us, refer to the table above for wire colors. Okay, listen carefully. First, wire in the red wire to RH, the green wire to G, the white wire to either W or W/E, and the yellow wire to Y or Y1. This is most people’s setup and there will be no more to go if you only have any combinations of the aforementioned wires. But just in case you don’t read paragraphs, but jump to more digestible content, here ya go:



Wiring Modes:

  1. Heat Only

Wiring for heat only requires two wires: to keep it simple, let’s say that is red and white. Take the red wire and tie it in to RH. If RH has a jumper to RC no worries. It comes this way! Tie the white wire to W. Put the face on and move to step six.







  1. Cool Only

Wiring for cool only requires two wires, red and yellow. Tie the red wire into R and the yellow wire into Y or Y1. If your wires are different colors, read above and good luck taking apart the HVAC equipment to find the IFC.


  1. Wiring for 1H 1C

First, wire in the red wire to RH, the green wire to G, the white wire to either W or W/E, and the yellow wire to Y or Y1.

  1. Wiring for 2H 2C

First, wire in the red wire to RH, the green wire to G, the white wire to either W or W/E, and the yellow wire to or Y1. Then, you need to tie in the secondary heat relay, probably brown to W2. Finally take what is probably orange and tie it in to Y2. Good luck! Here’s a schematic:


Step six: Operating the thermostat

At this point, you have wired in the mounting plate and are ready to push the face of the thermostat on the mounting plate. Tuck all the control wires in to the opening so that they are taking up as little space as possible. Take the face and line it up carefully with all pins and guides. Push against the face. Viola! It’s in! Do a happy dance. Install the batteries, and you should see the display light up. If you wired in a common wire, it will light up as soon as you push it in. It is still a good idea to install batteries even if common is wired in just in case there is a power outage and you lose your program you are about to put in.

Programming a Thermostat

Programming your thermostat is pretty easy. Keep in mind that your set program is always what the thermostat reverts back to when you adjust the temperature manually. I like to set this for maximum efficiency. You can do whatever you want. Most thermostats are shipped with an energy saving pre-program just in case you want to go with that; that’s like suuper efficient, but uncomfortable.



  1. Select Heat or Cool using the system selector button (or switch). Both heat and cool have to be programmed independently.
  2. Select Menu
  3. Select Set Sched. Some thermostats will come with a program for the entire week, some, like the T755, program both Saturday and Sunday independent of the week.
  4. Wake is the time you wake up set the time and temperature to your desired setting. Repeat this for , leave – the time you leave the house, return – the time you return to your house after you’ve left, and sleep – the time you go to bed and its corresponding temperature.
  5. Repeat programming sequence for weekend days.
  6. Select Done and go back to the primary operating screen.

Technician Mode Settings

To best keep this simple, I’m going to recommend you search for “BRAND + MODEL installation manual”. And follow the instructions there. This also tells you other more complex wiring configurations.



Also, if you need replacement parts, you can message me on the website messaging board with your model number and serial number. I can ship parts anywhere in the country. I do mark up my parts, but you get a whole better deal with me than with your local HVAC contractor. I also do facetime to help you install the component and return the unit back to working order for a small charge. Message me if you need help, that’s what I’m here for.