Coleman Furnace Troubleshooting: Common Twinning Errors and How to Fix Them

If you’ve ever operated or worked on a Coleman furnace, you may have experienced some difficulties. Most operators who have used these types of furnaces before will probably tell you that the learning curve on these is quite steep. The process of troubleshooting and fixing common twinning errors can be challenging and intimidating if you don’t know what you are doing. However, understanding the basic operating principles behind a Coleman furnace will greatly reduce your learning time and potential frustration levels. In this article, we discuss common Coleman furnace twinning issues and how to fix them. The digital version of this article includes 17 images for enhanced readability.

What Is a Coleman Furnace?

A Coleman furnace is a type of gas-fired central heating system that uses a gas burner to heat the air that is distributed throughout your home through ductwork. Like many other furnace types, a Coleman furnace uses the concepts of pressure and temperature to create heat. When the gas burner is turned on, the gas is ignited and burns at extremely high temperatures. This high-temperature gas is then sent through the combustion chamber and is mixed with cooler, surrounding air. The high temperature and pressure inside the combustion chamber cause the air and gas mixture to expand and exit the furnace as hot exhaust gases. To exit the furnace, this heated gas travels through a series of pipes and is distributed to the various air ducts in your home. From there, the gas travels through the ductwork and exits the furnace through the air filter and into the rooms in your house.

How Does a Twinning Error Occur?

A Coleman furnace twinning error occurs when there is too much pressure inside the combustion chamber. When this happens, the burner will be unable to put out enough heat to create sufficient airflow and pressure inside the furnace. The amount of pressure inside the combustion chamber during normal operation should be between 5 and 10 PSI. Any pressure outside of this range would indicate a twinning error. As you may imagine, several different factors could cause a twinning error. Below are a few of the most common causes and how a twinning error could occur: – The Air Flow Inside the Furnace is Too Little – If the airflow inside the furnace is too little, there will not be enough oxygen to burn the gas properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned gas. – The Gas Flow Inside the Furnace is Too Much – If there is too much gas flow inside the furnace, the airflow inside the combustion chamber will become insufficient. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned gas. – The Burner is Operating at an Incorrect Air-Gas Ratio – If the burner is operating at an incorrect air-gas ratio, there will not be enough oxygen inside the combustion chamber to burn the gas properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned gas.

Too Much Pressure-On-Bottom

Too much pressure on the bottom occurs when there is not enough airflow inside the furnace to burn the fuel properly. In this scenario, the unburned fuel would cause an increase in pressure inside the combustion chamber due to the excess pressure on the bottom. There are a couple of different ways that too much pressure on the bottom could occur: – The Gas Flow Inside the Furnace is Too Little – If the gas flow inside the furnace is too little, there will not be enough oxygen to burn the fuel properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned fuel. – The Air Flow Inside the Furnace is Too Little – If the airflow inside the furnace is too little, there will not be enough oxygen to burn the fuel properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned fuel.

Too Much Pressure-On-Top

Too much pressure on the top occurs when there is not enough airflow inside the furnace to burn the fuel properly. In this scenario, the unburned fuel would cause an increase in pressure inside the combustion chamber due to the excess pressure on the top. There are a couple of different ways that too much pressure on the top could occur: – The Gas Flow Inside the Furnace is Too Little – If the gas flow inside the furnace is too little, there will not be enough oxygen to burn the fuel properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned fuel. – The Air Flow Inside the Furnace is Too Little – If the airflow inside the furnace is too little, there will not be enough oxygen to burn the fuel properly. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned fuel.

Incorrect Pilot Flame Size for Main Burners

Incorrect pilot flame size for main burners occurs when the main burner flame is larger than it should be for the amount of fuel that is being fed into the furnace. In this scenario, the excess pilot flame would cause an insufficient amount of airflow inside the furnace to burn the fuel properly. Fuel starvation would cause an increase in pressure inside the combustion chamber due to the unburned fuel. This could occur if the pilot burner parts are clogged and are not able to open the main burner valves when they reach a certain temperature.

Incorrect Regulator Setting for Pilot and Main Burners

Incorrect regulator setting for pilot and main burners occurs when the main burner gas pressure is set too high for the amount of fuel being fed into the furnace. This would cause fuel starvation and an increase in pressure inside the furnace due to the unburned gas. This could occur if the furnace pressure regulator is set too high and restricts the amount of gas flowing into the furnace.

Conclusion

While troubleshooting and fixing Coleman furnace twinning errors can be challenging, the process is not impossible. By understanding the basic operating principles behind a Coleman furnace, you can reduce your learning time and potential frustration levels. Furnaces are complex machines and are often prone to error. It is important for anyone working in the HVAC industry to familiarize themselves with common twinning errors and how to fix them.