Field glossary

Pre-charge

The air pressure on the sealed side of the tank, set to match the system static pressure before the tank is connected

Used across 3 Anvilfield field guides, most in Plumbing.

Also defined as

HVAC: The air pressure set in a diaphragm or bladder tank, checked dry, matched to the system cold fill pressure
The tank air pressure, set about 2 psi below cut-in with the tank empty

Where this shows up