The unit typically ships with the Natural Gas orifice installed

it requires a minimum operating pressure differential of 5 PSI to function correctly and ensure the diaphragm shifts properly

making it a "truck stock" essential for residential and commercial service calls

How do I verify if this fits my specific Lochinvar or A

Siemens Combustion VGD40.065U Valve Body 322838-754 The unit typically ships withThe Siemens VGD40. 065U is a high capacity 2 1 2" NPT double gas valve body engineered for integration with SKP series electro hydraulic actuators. This double block valve configuration is designed to manage the flow of natural gas, propane, and air in commercial and industrial combustion systems. Built with a robust die cast aluminum housing, the VGD40. 065U provides a compact footprint while maintaining high flow rates with minimal pressure drop. It