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Pressurestat
Mechanical pressure switch that turns the heating element on and off to hold the steam boiler at a set pressure — the analogue ancestor of the PID.
Category: Boilers & Heating
The older mechanical pressure-controlling switch on a steam boiler. The pstat senses boiler pressure with a Bourdon tube or diaphragm and switches the heating element on or off to hold a set pressure.
Why it matters — On non-PID machines, the pstat is what holds steam pressure stable. A failing pstat causes pressure swings, element cycling problems, and inconsistent steam.
Good to know
- Common brands: Sirai, Mater, Ceme. Replacements are widely available and interchangeable on most machines.
- A pstat that's audibly clicking on and off rapidly (every few seconds) is usually failing — replace it before the contacts weld shut.