To convert any UDSA-4E units from propane to natural gas, please view this document: https://www.reznor.co.uk/wp-content/uploads/2025/09/Option-3-11-1-3.11.2-UDSA-4E-1.pdf. The part number for the jet is 07-25806-520 (https://www.reznor.co.uk/product/gas-injector-5-20mm-lpg-g31/).
How do I convert a UDSA-4E from propane to natural gas?
Information on Reznor's range of warm air heaters