by High Performance HVAC | Gas Furnaces |
Gas Furnace Components 3 - Gas furnace ignition controls vary from furnace manufacturer to furnace manufacturer. Some are proprietary and some are from an engineering company that specializes in gas furnace ignition controls. Honeywell being a major manufacturer of controls for HVAC also makes several gas furnace ignition controls.
Gas furnace ignition controls have advanced by leaps and bounds over the last 20 years. The standard was standing pilot ignition. Solid-state ignition controls are safer and more efficient than ignition controls of yesteryear.
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by High Performance HVAC | Thermostats |
Thermostat Wiring Colors Code Page Navigation
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- Essential Thermostat Wiring Color Guide Including Manufacturers Instructions
- Thermostat Terminal Designations Quick Guide - Detail Wiring Color Guide Below
- Red-Wire - connects to the R terminal with the red wire
- RC-Wire - connects to the RC terminal RC red
- RH-Wire - connects to RH terminal RH heat
- Y-Wire - connects to the Y terminal and is for cooling stage 1 with the yellow wire
- Y2-Wire - connects to Y2 terminal and is for cooling stage 2
- W-Wire - connects to W terminal and for heat stage 1 with the white wire
- W2-Wire - connects to W2 terminal and for heat stage 2
- G-Wire - connects to G terminal and for fan operation with the green wire
- C-Wire - connects to C terminal (common 24v power) with the C wire
- O or B-Wire - connects to O or B terminal and is for reversing valve operation
- E-Wire - connects to E terminal and is for Emergency heat
- X or Aux-Wire - connects to X terminal and is for auxiliary
- S1 and S2 Wires - connects to S1/S2 terminals and is for outdoor temperature sensor
- Thermostat Wire Color Code Chart
- Tracing the Wire to the Source
- Additional Resources
What you will learn in the
Thermostat Wiring Colors Code article:
- First, what thermostat wire colors is likely to go to which terminal on the thermostat in your heating and cooling system
- Secondly, the function of each wire terminal on the average thermostat highlighting some of the differences in those HVAC system functions from manufacturer to manufacturer as recommended for thermostat wire color
Thermostat Wiring Colors Code | HVAC Control
Always follow the thermostat manufacturer’s instructions whenever changing the thermostat. Always turn the power off at the air handler and the condenser and make sure there is no voltage at the transformer before proceeding.
Furthermore, the thermostat wire colors below are the most likely colors used for most installations; however, your thermostat wire colors may be different than what the indication is here. There is no official standard for thermostat wire colors. Additionally, thermostat wiring colors are not standardized. However, these are the most wiring methods used based on my years of experience in the HVAC field, where I successfully wired a lot of thermostats and as recommended by manufacturers and common sense for thermostat wiring colors code.
For instructions on how to wire a thermostat, please see how to wire a thermostat page. Refer back to this page for thermostat wire colors.
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by High Performance HVAC | Commercial HVAC |
Hot Water Unit Heater Protecting Mechanical Room - Unit heaters are used in various places to protect equipment and provide comfort to occupants. This hot water unit heater provides protection for a mechanical room where there is a large air handler and other associated equipment in the mechanical room. This system is controlled by DDC. A thermostat on the wall detects the temperature of the mechanical room. (more…)
by High Performance HVAC | Oil Heat |
Furnace and Boiler Oil Filters - Oil burner oil filters are important to keep trash out of the burner gun and plugging the nozzle. A dirty filter can also choke the system from firing properly by preventing the correct amount of oil flow from reaching the nozzle. Oil furnace oil filters or oil boiler oil filters should be changed on at least an annual basis. More if the oil or oil tank is of poor quality. It is also recommended that the oil furnace or oil boiler be shut down when oil delivery is made.
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by High Performance HVAC | Thermostats |
Types of HVAC Thermostats | HVAC Control There are many different types of thermostats. Thermostats also have various levels of complexity. Below is a list of the basic thermostat types. As we have time we will update the list to make sure it is as comprehensive as possible. (more…)
by High Performance HVAC | Gas Furnaces |

Gas Furnace with Drain Pipes to Drain the Condensation.
Furnace Water Leak Condensate Problem - Richard, My furnace is leaking water. It is summertime, so I am not using it for heat except for the blower fan which is hooked up to the air conditioner and the heat. I know the pipes from the outside units run into a box on top of the furnace. I think that is a part of the air conditioner. What can I do to fix the problem if you know what the problem is by my explanation here? Dan
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by High Performance HVAC | Oil Heat |
Oil Furnace Boiler Pump - A major component of oil furnaces is the oil pump and its job is to pump oil from the oil tank to the oil burner. It is important that the oil system is primed and free of any objects or particles that can plug the system. As well the oil pumping system must have integrity with no holes in the oil pipe where the pump can suck air into the oil line. Any air sucked into the line or a plugged oil line will cause problems with the oil burner that may result in a non-functional burner or a burner that does not produce efficient heat. (more…)
by High Performance HVAC | Heat Pumps |
Heating with Heat Pumps | HVAC Systems - There are some people who say that heat pump heat is not as warm as other types of heat. Heating sources such as a hot water boiler or even a steam boiler. Even the forced air gas furnace gets more credit for providing better heat than the heat pump. Heat pumps are extremely popular in the southern states where the heating season is short. Additionally, where the temperature rarely dips below 35 degrees F. (more…)
by High Performance HVAC | Technical Reference |

Bacharach Combustion Analyzer
Bacharach Combustion Analyzer Furnace Testing - The combustion analyzer is used to test gas and oil furnaces to make sure the combustion process is as efficient as possible. This multi-function HVAC test instrument can also be used to test spaces for carbon monoxide, test building pressure, all in addition to testing the combustion process of the furnace.
The combustion analyzer allows an HVAC technician to test the flue temperature, the amount of oxygen in the furnace flue gases, the amount of carbon monoxide in the flue gases, the amount of carbon dioxide in the flue gases, and the pressure of the flue. All these readings are necessary so the HVAC technician can make adjustments to the burner settings to ensure efficient combustion using the combustion analyzer. (more…)
by High Performance HVAC | Gas Furnaces |

Furnace with Hot Surface Ignition
Hot Surface Ignitor - Whenever we talk about electronic ignition systems in gas furnace ignition systems we must first look at the key components which make these systems work and understand how they work. Hot surface ignitor systems work in various ways.
This all depends on what the electronic ignition manufacturer and design engineer determined in the design. Furthermore, some are direct main burner ignition while others light a pilot, and the pilot lights the main burners.
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