Natural gas heaters cannot use propane without modification, as they are designed for specific fuel types, but conversion kits are available for some models to allow the use of propane instead of natural gas.
Natural gas heaters cannot use propane without proper conversion. The two fuels have different pressure requirements and energy densities, making them incompatible in their default configurations. Attempting to use propane in an unconverted natural gas heater can lead to dangerous situations, including excessive heat output and potential equipment damage.
Key Differences Between Natural Gas and Propane
Understanding the fundamental differences between these fuels is essential for safe operation:
| Characteristic | Natural Gas | Propane |
|---|---|---|
| Energy Content | 1,030 BTU/cu ft | 2,516 BTU/cu ft |
| Delivery Pressure | 0.25 psi (low pressure) | 10-11 psi (high pressure) |
| Storage | Piped through utility lines | Stored in pressurized tanks |
Why Conversion Is Necessary
Propane contains about 2.5 times more energy per cubic foot than natural gas. When used in an unconverted natural gas heater, propane will flow at higher pressure through larger orifices designed for natural gas. This creates several potential problems:
- Excessive flame temperature that can damage heat exchangers
- Incomplete combustion leading to carbon monoxide production
- Potential for flame rollout or backdraft conditions
- Reduced appliance lifespan due to overheating components
Conversion Process for Natural Gas Heaters
Converting a natural gas heater to propane requires several modifications:
1. Orifice Replacement
The burner orifices must be replaced with smaller ones designed for propane’s higher energy content. This controls the gas flow rate to maintain proper combustion.
2. Pressure Regulator Adjustment
The gas pressure regulator must be adjusted or replaced to handle propane’s higher delivery pressure. Most natural gas regulators cannot properly reduce propane’s 10-11 psi down to the required 11″ water column.
3. Gas Valve Adjustment
The appliance’s gas valve may need recalibration to ensure proper gas flow at all settings. Some valves have internal adjustments for different gas types.
4. Combustion Analysis
After conversion, a combustion analysis should verify proper operation. This measures flue gas composition to ensure complete combustion and safe operation.
Safety Considerations
Improper conversion can create serious hazards. According to research on propane heater fumes, incomplete combustion can produce dangerous carbon monoxide levels. Other risks include:
- Fire hazards from excessive flame temperatures
- Gas leaks from improper fittings or connections
- Equipment failure from operating outside design parameters
For these reasons, conversion should only be performed by qualified technicians familiar with proper venting requirements and local codes.
When Conversion Isn’t Possible
Some natural gas heaters cannot be safely converted to propane due to:
- Incompatible heat exchanger materials
- Lack of available conversion kits
- Manufacturer restrictions
- Age or condition of equipment
In these cases, replacing the heater with a properly designed propane model is the safest option.
Maintenance After Conversion
Converted heaters require special attention:
- Annual professional inspection
- More frequent burner cleaning (propane can produce more soot)
- Regular CO detector testing
- Monitoring for yellow flames (indicates combustion problems)
Properly converted and maintained, propane can be an excellent fuel source. However, the conversion process is not a DIY project and requires professional expertise to ensure safe operation.
