Proudly American
Start with both labels if available
Look in existing records for the original gas designation, serial number and any later conversion label or invoice. NG generally denotes natural gas and LP refers to liquefied petroleum gas. If the original listing and a later service record disagree, leave the appliance disconnected or off and have a qualified gas professional establish its present configuration.
Check the model suffix and serial range
The Heatilator manual linked below illustrates why serial numbers matter. Its parts table assigns different conversion kits to different production ranges of the same product family. Another model or serial range may have no approved conversion available. Ask for the document and kit number that apply to this unit, not just the brand name stamped on the front.
Ask for the finished service record
A conversion involves the fuel-burning system and should be evaluated and performed by a professional qualified for gas work. Request a record showing the final fuel designation, parts used, applicable labeling and completed operational checks. Keep those details with the appliance manual for the next service visit or change of ownership.