| Replacing thermostat by yourself without a Denver | | | | company. |
| HVAC technician can be pretty harrowing if you do | | | | W is the heating terminal. W is for white terminal. |
| not hook up the wiring correctly. Inside of the | | | | This should go directly to your heating source, |
| thermostat there are several terminals which must | | | | whether it be a furnace or boiler. W2 is for second |
| hook up with the right wires. The R-terminal is the | | | | stage heat and is usually brown. This is for gas |
| thermostat's power. R means Red, the Colorado | | | | furnaces with low and high settings. Heat pumps use |
| heating repairman should have red wires going to this | | | | W2 for auxiliary heat. |
| terminal. This power comes from the transformer. | | | | G is for green and goes to the indoor blower fan |
| The transformer is usually in the condensing unit or | | | | relay. |
| the air handler in a split system. Because they are | | | | C is for Common, and does not have a specific color |
| supplying power, it is a good idea to kill the power to | | | | although black is seen frequently. For digital |
| both the condenser and the air handler before | | | | thermostats that consume power, the common wire |
| working on the thermostat. | | | | is necessary to complete the 24 volt circuit. |
| The RC terminal is the power for cooling. Some large | | | | Orange "O" and "B" Blue are for heat pumps. Rheem |
| HVAC systems have two transformers, one for | | | | and Ruud heat pumps use the B terminal for the |
| cooling and one for heat. In such a case, the power | | | | cooling reversing valve. Other HVAC manufacturers |
| from the ac system goes to the thermostat terminal. | | | | use the O terminal. Trane, Lennox, Goodman, |
| A jumper can be installed between RC and RH for a | | | | Ducane, Heil, Carrier, Fedders, Amana, and Janitrol are |
| single transformer heating and cooling system. The | | | | normally hooked up to the O terminal by HVAC |
| RC terminal is also red. | | | | contractors in Denver. |
| The RH terminal is the heating power-in. This is also | | | | E is for emergency heating. This has no standard |
| red and can be jumped to the RC. | | | | color but should be wired to the heating relay or E |
| The Y terminal is yellow and goes to the compressor | | | | terminal strip board. |
| relay. Some Denver HVAC specialists use a terminal | | | | S1 and S2 are for outdoor air sensors. This has no |
| board strip on the air handler control board which | | | | standard color, but should use a shielded wire to |
| makes splices not needed. Y2 is usually light blue and | | | | reduce interference and the possibility of water |
| is the code for a second stage cooler. If you do | | | | damage from outside. Warning: These colors are the |
| have two compressors, both should work off the | | | | defaults. The person wiring the thermostat could |
| same thermostat. Most Denver heating and air | | | | have used unconventional color coding. |
| companies do not need the cooling of a two stage | | | | |