Converting a natural gas furnace to propane is a feasible process, but it requires specific adjustments and careful execution to ensure safety and proper operation. The conversion process involves replacing the burner orifices, adjusting the gas valve, regulating the pressure settings, and ensuring proper piping and connections. Safety considerations are crucial, and it is highly recommended to hire a qualified HVAC technician to perform the conversion.
What is the Conversion Process?
- Orifice Replacement:
-
The primary step involves replacing the burner orifices. Natural gas orifices are larger than those for propane due to the different pressures and calorific values of the gases. For propane, smaller orifices (typically a drill size of 55) are needed to match the higher pressure and calorific value of propane compared to natural gas (which uses a drill size of 43 or 45).
-
Gas Valve Adjustments:
-
The gas valve must be adjusted to accommodate the higher pressure of propane. This usually involves changing the regulator spring and adjusting the gas pressure settings. For propane, the manifold pressure should be set to around 10 inches of water column, whereas for natural gas, it should be set to about 3.5 inches of water column.
-
Regulator and Pressure Settings:
-
The inlet pressure for propane should be at least 11 inches of water column, while for natural gas, it should be around 7 inches of water column. These settings are crucial to ensure the correct gas flow and to prevent over-firing or under-firing of the furnace.
-
Piping and Connections:
-
Ensure that all piping and connections are secure and meet the necessary codes. This includes proper support for the piping and adherence to safety standards, such as the placement of shut-off valves.
-
Testing and Verification:
- After the conversion, it is essential to test the furnace to ensure it operates correctly. This includes checking the flame appearance, gas pressure, and ensuring there are no leaks.
What are the Safety Considerations?
- Professional Assistance:
-
While it is possible to perform the conversion without professional assistance, it is highly recommended to hire a qualified HVAC technician. Incorrect conversions can lead to safety hazards, including the risk of carbon monoxide poisoning, explosions, or fires.
-
Potential Risks:
- Running a gas furnace on propane without a proper conversion can lead to several risks:
- Over-firing: Using natural gas orifices with propane can cause the furnace to over-fire, stressing the combustion chamber and potentially leading to carbon monoxide leaks.
- Explosions: Propane is heavier than air and can accumulate in low-lying areas, increasing the risk of explosions if not handled correctly.
- Inefficient Operation: Incorrect settings can result in inefficient heating and increased energy costs.
What are the Specific Requirements and Designs?
- Conversion Kits:
-
Most manufacturers provide conversion kits specifically designed for their furnaces. These kits typically include the necessary orifices, regulator springs, and instructions for the conversion.
-
Compatibility:
- Not all gas furnaces can be converted to propane. The furnace must be designed to accommodate the conversion, and the manufacturer must provide a conversion kit. Always check the manufacturer’s specifications before attempting a conversion.
What Tools, Costs, and Materials are Needed?
- Tools:
-
Orifice drill bits, wrenches, manometers, and pressure testers are necessary for the conversion.
-
Costs:
-
The cost of the conversion kit and any additional materials can vary depending on the manufacturer and the specific furnace model. Labor costs for hiring a professional can also add to the overall expense.
-
Materials:
- Conversion kits, orifice drill bits, regulator springs, and possibly new piping or connections may be required.
