Thermador Pro Grand LP conversion notice — owners of Thermador Pro Grand, Pro Harmony, and Professional Series gas ranges who need to convert from natural gas to liquid propane (or vice versa) are advised that this conversion is a certified-technician-only procedure. DIY conversion is not safe and is prohibited by Thermador warranty terms.
Why this matters
Gas range conversion involves replacing the burner orifices, the bake and broil orifices, the regulator setting, and in some cases the safety valve assembly. The orifice sizes for natural gas and liquid propane are not interchangeable — natural gas orifices are larger because natural gas has a lower energy density per cubic foot than propane. Installing the wrong orifices, or failing to adjust the regulator for the new fuel type, results in either dangerously high flame output (natural gas orifices on propane) or starved combustion that produces carbon monoxide (propane orifices on natural gas).
Why DIY conversion is not safe
- Conversion requires removing the cooktop manifold to access internal components — incorrect reassembly can cause gas leaks
- The regulator must be physically reconfigured (not just turned with a wrench) to switch fuel types
- Each burner orifice must be torqued to a specific specification — too loose causes gas leaks; too tight can crack the burner spud
- The conversion kit includes specific orifices matched to your exact range model and serial number — wrong orifices for the model can cause flame impingement on the burner caps
- After conversion, every burner must be tested for proper flame appearance, and the safety solenoid must be verified to shut off gas flow correctly when the flame is extinguished
Required steps for conversion
- Order the official Thermador LP conversion kit for your specific Pro Grand model from BSH parts
- Schedule a Thermador-certified or BSH-authorized gas service technician to perform the installation
- The technician verifies the new fuel supply line is properly sized and pressure-tested
- The technician installs the conversion kit and adjusts the regulator
- The technician tests every burner, the bake element, the broil element, and the safety solenoid
- The technician verifies no gas leaks at any connection using a calibrated leak detector or soap solution
- The technician affixes the conversion certificate sticker to the back of the range documenting the new fuel type
Warranty implications
Thermador warranty coverage is voided if the gas range is converted without using a certified technician. Insurance claims for fire or carbon monoxide events may also be denied if the range was converted by an unauthorized installer.
Carbon monoxide warning
Improperly converted gas ranges are a leading cause of residential carbon monoxide events. Always have a working CO detector in the kitchen and adjacent living spaces. If a CO alarm sounds, evacuate immediately and call emergency services.
Related Thermador Safety & Repair Resources
Related Safety Notices
- Thermador Pro Grand Griddle and Grill Cleaning Safety Notice
- Thermador Dishwasher Power Cord Fire Recall 2017 | CPSC
Related Repair Guides
- When to Replace a Thermador Range (Not Repair)
- Thermador Range Burner Not Igniting: Star Burner Troubleshooting
Schedule Thermador Appliance Repair with a Thermador-certified technician.