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Pressure Relief Valve (Safety Valve)
Spring-loaded boiler safety valve that vents steam if pressure runs away — the last line of defence against a boiler rupture.
Category: Boilers & Heating
A spring-loaded valve that opens automatically if boiler pressure exceeds a safe limit — typically 1.8–2.5 bar for steam boilers. Required safety component on every pressurised espresso machine.
Why it matters — The relief valve is the last line of defence against an over-pressurised boiler. If everything else fails (failed pstat, stuck heating element), the relief valve vents pressure and prevents a boiler rupture.
Good to know
- The valve should never operate in normal use. If it lifts during normal idle, something upstream is broken — usually the pressurestat.
- Relief valves can scale shut over years in hard-water areas; they should be inspected during regular service.