How do I turn down the steam boiler pressure?

January 28th, 2008, 4:52 am

Here's a look at the inside. I remember someone suggesting that I turn down the boiler pressure from 1.25 to .8 because I'm not pouring many shots. But how exactly do I do that? If someone could just point me toward the screw, and tell me which way to turn and how much. I'd be very appreciative. I'll probably have a few more questions when I install her sometime this weekish... This a top view of her insides. The front is indicated.

#2: Post by **zarko** » January 28th, 2008, 6:27 am

You would need to adjust pressurestat (marked on your photo).
If yellow thing is not a screw it's possible that you will need to take a cap off to adjust it.

Zarko

#3: Post by HB » January 28th, 2008, 7:25 am

PhaetonFalling wrote:If someone could just point me toward the screw, and tell me which way to turn and how much. I'd be very appreciative. I'll probably have a few more questions when I install her sometime this weekish...

See How to adjust an espresso machine pressurestat from the FAQs and Favorites Digest. That looks like a Sirai pressurestat.

zarko wrote:If yellow thing is not a screw it's possible that you will need to take a cap off to adjust it.

The adjustment screw is directly beneath the yellow cap. I find it easier to remove the whole cover to avoid screwdriver slips.

February 21st, 2008, 5:06 pm

Thanks Dan...

So I adjusted it down, and she doesn't heat up quite so badly anymore, the flush is a lot shorter. Better for home usage.

Just looking at the picture... where the hell is the OPV located...I've been looking for it, but I can't tell where it's supposed to be. I've read about how to turn it down, I just don't know where it is.

Sincerely,

Namson Pham

#5: Post by HB » February 21st, 2008, 5:21 pm

PhaetonFalling wrote:Just looking at the picture... where the hell is the OPV located...I've been looking for it, but I can't tell where it's supposed to be. I've read about how to turn it down, I just don't know where it is.

Although they're the same part, an OPV (over-pressure valve) and expansion valve serve different purposes. For a vibe pump, an OPV regulates the maximum pressure by releasing water back to the reservoir. A rotary pump uses a bypass valve on the pump itself for this purpose, i.e., water pumped out is routed back to the pump above the setpoint. The expansion valve for a rotary pump espresso machine assures the pressure of the system doesn't exceed a safe limit (usually 12 bar). It cracks open as the boiler heats up, hence why it's referred to as an expansion valve in this case.

If you peruse the FAQs and Favorites Digest, I believe you'll find more explicit instructions for adjusting a rotary pump espresso machine (just a guess, I haven't looked lately).