Pressurestat (pstat)

Mechanical pressure switch that cycles the steam boiler element on and off to hold a set pressure — typically 1.0–1.5 bar.

Category: Boilers & Heating

A mechanical pressure-controlled switch that turns the heating element on and off to maintain a target steam boiler pressure. The traditional control method before PID controllers became standard.

Why it matters — On machines without a PID on the steam circuit, the pstat is what determines whether your steam pressure is stable. A correctly working pstat holds pressure within 0.1–0.2 bar of target; a failing one swings wildly.

Good to know

Pstats can be adjusted with a small screwdriver — typically a quarter-turn changes pressure by 0.1–0.2 bar.
If you upgrade to PID control later, the pstat usually stays in place as a backup safety control set slightly higher than the PID target.