What is water column inches (WC)?
Water column inches (WC) is a unit of measurement for gas pressure in propane systems, where 1 inch of WC equals the pressure exerted by one inch of water in a vertical column.
Most propane appliances in Florida homes run on very low pressure compared to natural gas systems. Water column inches, abbreviated WC, measure this low-pressure range using a simple reference: the weight of water. One inch of WC represents the pressure that one inch of standing water exerts downward, equivalent to about 0.036 pounds per square inch (psi). Propane suppliers and technicians use this unit because residential systems typically operate between 4 and 14 inches WC, making it a practical scale for gauges and testing equipment.
Different appliances require different pressure ranges. A typical propane water heater operates around 10 to 14 inches WC, while a furnace or range might run at 8 to 11 inches WC. Pressure that is too high or too low causes problems: low pressure results in weak flames or incomplete combustion, while high pressure can damage regulators and create safety hazards. Propane suppliers often measure and verify WC during service calls to ensure appliances are working correctly and efficiently. Understanding WC readings helps homeowners and service technicians troubleshoot performance issues and confirm that the regulator is delivering gas at the proper level for safe operation.