Pressurestat vs PID for steam - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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Jeff
Team HB

#11: Post by Jeff »

Pressure and temperature are tied to each other in a typical steam boiler. A "saturated steam table" gives relationship. Control one, you control the other.

The screw is pressure. I don't believe the miniature ones are adjustable for dead band. (I'm mistaken, at least this one is adjustable - https://www.espressocare.com/products/i ... -dead-band)

I don't see an adjustable dead band as an advantage if you've got a SSR (which you should with these miniatures.) Wider dead band means fewer on/off cycles, important to preserve switch contacts and potentially thermal load changes on high-power elements.

If you're seeing much more than the 0.2 bar dead band (watch the heater-on light), the pressurestat may be failing, it or the tubing to it may be clogged with scale, or the micro switch is sticky. CEME is another affordable, compact pressurestat. Check the contact ratings if you swap brands. I seem to recall that the CEME units can't take the 10-15 A that is needed for a 120 V element without a relay. (230 is roughly half the current.)

See also How to replace MATER with CEME pressurestat?

BenS (original poster)
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#12: Post by BenS (original poster) »

Thanks Jeff,
Jeff wrote: If you're seeing much more than the 0.2 bar dead band (watch the heater-on light), the pressurestat may be failing, it or the tubing to it may be clogged with scale, or the micro switch is sticky.
Will pay closer attention to the light but full pressure is 1.25bar and I don't hear the click until .8bar - maybe .9 but will check.

For anyone else reading this thread, there's also some general info here:
How to adjust an espresso machine pressurestat (boiler temperature)

Cheers

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cafeIKE
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#13: Post by cafeIKE »

A PID is nearly instant, but element still has to heat.

You could also use a SS pressure sensor to control an SSR. Not cheap but very reliable and no CLACK.

A tip with fewer / smaller holes will drop the pressure less.