| Terminal | Color | Control |
| C | Black | 24V Common |
| R or V | Red | Source 24V Power |
| RH or 4 | Red | 24VAC for Heat |
| RC | Red | 24VAC for Cool |
| Y | Yellow | Cooling |
| W | White | Heat |
| G | Green | Fan |
| Y2 | Can Vary | Heat Pump 2nd Stage Cooling |
| W2 | Can Vary | Heat Pump 2nd Stage Heating (Emergency Heat?) |
| E | Can Vary | Heat Pump Emergency Heat |
| O | Orange | Heat Pump Reversing Valve |
Are there different types of thermostats available?
Yes, and you should choose the type that best suits your needs.
Thermostats are both analog and digital devices, and many have programming capabilities.
Most of these, at a bare minimum, have the ability to start and stop the system at predetermined times.
The number of programmable times that are available in a 24-hour period depends on the thermostat you select.
Prices vary widely, so give it some thought.
What features should I look for in a thermostat?
The thermostat should be programmable.
This will save money by turning the system on and off at the times you choose. If your weekday schedule is relatively constant, then you can get a thermostat that has weekday program and separate weekend program capabilities.
Then you can program one time for the entire week, and start and stop times as well as the temperatures you like for the weekend.
If your weekly schedule is erratic, use a thermostat that allows you to program each day separately.
Although most do, make sure your thermostat has a battery back up.
Should the power fail, you won't lose your program.
Programming these devices isn't difficult, but it is an inconvenience if you have to do it more than once.
Select a thermostat that has a number of daily events that are right for your lifestyle.
It is a waste of money to buy a thermostat that has too many events, especially if you are going to program these at the same temperature.
I can’t even program my cell phone.
Older programmable thermostats were more difficult to program than the ones we have today.
The directions are easy to follow and you can complete the whole process in less than 10 minutes.
Read the manual !!!
Does my thermostat need batteries?
Most programmable thermostats do have batteries.
These power the chip that stores your program, should the power go off.
Refer to the manual for directions on where the batteries are and how to change them.
And keep spare batteries on hand.
In a pinch, you can “borrow” them from your kid’s handheld electronic video games.
If your thermostat is an analog device (with mechanical pointers and manual rotating or sliding temperature adjustments) and has no clock, your thermostat does not need batteries.
How do I get a new manual?
Look for the name of the manufacturer and the model number of the device.
You may have to remove the cover to see this.
Search the Internet for their website and contact customer service fora new manual.
You might be able to download the manual right from their website as a PDF document.
I knocked the thermostat off the wall.
The thermostat has two parts: the thermostat body and the subbase.
The subbase is the part that mounts to the wall and this is where the electrical connections are.
If the subbase is intact and the thermostat body came loose, simply replace the thermostat body on the subbase.
But before you do, turn off the power to the appliance.
That will prevent any electrical arcing from damaging the thermostat's electronic circuitry.
If the wires got disconnected from the thermostat, turn off the power first.
Reattach while observing the color coding.
Turn the power back on - you should be done.
If it doesn't work, check the fuse on the circuit board (usually inside the furnace).
If the circuit board doesn't have a fuse, you MAY have to replace the board.
Generic replacements are usually fine.