Help identifying wires

[Ccothren8]

I'm having issues figuring out what wires are what. I have an X1 and can't find that on any of the wires on the list 🤔 I have a normal heat pump, but also have gas emergency heat 

[CoolingWizard]

@Ccothren8,

If you have a Heat Pump your current thermostat should have Rc, G, Y1, OB, W2. If you have a gas furnace you have what is called a dual-fuel system.  You will have Rh and W1 for the gas furnace.  The X1 wire is a programmable terminal often used for Emergency Heat function.  Now if your furnace cabinet has also electric heat strips they will be activated by W2 as heat pump auxiliary heat.  Or in an emergency heat function using X1.  
In all reality since you have duel-fuel system you will not need emergency heat since you have the gas furnace.  
In a duel-fuel system your task is to determine at which temperature you should switch from Heat Pump heat to gas heat.  Typically it is around 25 to 23 degrees F depending on the cost per therm of natural gas in your area. 

AC Cooling Wizard 

[Ccothren8]

It won't allow me to post a picture for some reason, but with our dual heat the gas is only used when switched to emergency heat. It doesn't automatically come on we have to physically do it ourselves. Our thermostat box on the wall is very old school and said "DICO" on it 

[CoolingWizard · Accepted solution]

@Ccothren8 ,

in order to post a picture here for security reasons you have to click the link in the email that Google sent you when you created this Google nest community account. Once you validate your email, you’ll be able to post pictures. 

Ok, when you have a dual-fuel system and a very smart thermostat such as a Google Nest Learning thermostat, you have the ability to use the gas furnace, not only as emergency heat, but you can use it as supplemental heat or alternative heat, depending on the temperature outside. 

When you have a Heat Pump system your Heat Pump is the primary heat source.  Depending on where you live, the Google Nest Learning Thermostat can automatically switch to Gas Heat when the outdoor temperature gets very low.  As the outdoor temperature decreases, the heat pump has to work harder to extract heat.  At about 23°F, it can be more advantageous to switch to the Gas Furnace.  

Emergency Heat by its nature is always manually turned on.  The concept for its creation is that your electric heat pump fails in the winter and you need some kind of heat while you wait for the repairman to arrive.  The answer is Emergency Heat.  With a normal heat pump installation. The air handler has 10 to 15 KW heat strips installed in the air handler. This is the heat pumps, auxiliary and emergency heat. When you have a gas furnace, we call this a dual fuel system because you have two primary types of heat.

AC Cooling Wizard

AC Cooling Wizard

[Ccothren8]

Here is a picture of our wiring. I'm honestly still lost on how to do this and even more confused on if I bought the wrong nest? It doesn't say what nest it is just says "nest thermostat" on the front of the box 

[Ccothren8]

The bottom brown wire is connected to X1 

[CoolingWizard]

@Ccothren8 ,

If your nest thermostat box simply says “nest thermostat”, you have the basic nest thermostat, which will require a couple AA batteries. This will still work with a single stage heat pump

can you get me the model number of the thermostat your base you have there?

AC Cooling Wizard 

[Ccothren8]

For the thermostat we have already or the nest one? 

[CoolingWizard]

@Ccothren8 , I would like to get the manufacturer and model number of your old thermostat. That’s still on the wall. 

AC Cooling Wizard