Pressurestat threads

[timo888]

On an Italian spare-parts website, the thread of the CEME and MA-TER ¼" pstats is stated as 13mm. Is this a metric thread with a 1.25 pitch?

Regards
Timo

[erics]

1/4-19 BSPP threads have an OD of 13.16 mm and their pitch would be 1.337.

I do not believe there exists a "normal" 13 mm metric thread.

[PaulTheRoaster]

My spare Sirai p-stat has a male 1/4" BSPP connector. 1/4" ID, 1/2" OD, which is quite close to 13 mm. I assume they're all the same. Don't you love nominal units?

[timo888]

1/4-19 BSPP threads have an OD of 13.16 mm and their pitch would be 1.337.

I do not believe there exists a "normal" 13 mm metric thread.

Eric,
Thanks for the reply. So the CEME and MA-TER use BSPP?

On my metric thread gauge, the 1.25 fine teeth are a good fit or the male thread on my Cremina's pstat; it has a 13mm OD. Would the female thread then be a M12x1.25?

Can I use the standard 1/4" CEME or MA-TER pstat with the Cremina? Is that .08mm difference in pitch small enough to be of no concern, perhaps with a little teflon tape?

Regards
Timo

[erics]

Dave Blaine - http://www.hitechespresso.com/ - who posts a lot on AC, was pretty much giving away CEME pstats for the cost of postage. This, as a result of his PID'ing a lot of Quickmill hx machines.

HOWEVER, on the Quickmill machines, the pstat controls a 25A SSR which switches the heating element - a real nifty setup. So, installing a replacement pstat on a Cremina, whose original pstat MAY control the heating element directly, needs a little thought.

Even sitting here in Silver Spring, MD, I'm pretty convinced that your original pstat has 1/4"-19 BSPP threads and the corresponding female thread would also be the same size, i.e. a 1/4-20 bolt gets a 1/4-20 nut and a M10 x 1.5mm bolt gets an M10 x 1.5 mm nut, etc., etc.

See here:

http://mdmetric.com/tech/tict.htm

The CEME is a nice pstat but I would be a little cautious on the contact's amperage capability.

[timo888]

... installing a replacement pstat on a Cremina, whose original pstat MAY control the heating element directly, needs a little thought.
...
I would be a little cautious on the contact's amperage capability.

All I know about the Oly's pstat is that is has bellows and a microswitch. Is there any way to tell, by looking, whether it controls the element directly? I am clueless about electrical circuits.

Regards
Timo

[erics]

Well, I guess the easiest way for you to tell would be to trace the wires from the heating element.

Assuming your heating element IS NOT controlled by a solid state relay (SSR), one lead from the heating element PROBABLY goes directly to a terminal board where it connects with the line neutral (white). The other lead from the heating element PROBABLY goes to a safety thermostat (boiler mounted) and then on to the pstat terminal marked NC (normally closed). The other lead from the pstat terminal marked C (Common) goes to the terminal board previously mentioned and connects up with the line hot (black).

Obviously, I forgot to mention the main power on/off switch in the above paragraph which probably switches both the incoming hot and neutral - typical of most espresso machines also designed for the European market.

I, of course, gladly defer to any Cremina owner for corrections to the above.

[erics]

The electrical circuit of a Cremina is described in detail on Page 3 of this excellent restoration post:

http://www.home-barista.com/forum...-cremina-t464.html

The pressurestat controls the heating element directly and something like a CEME would not be a good choice in that application. The only pressurestat that I am aware of that controls the heating element directly is a Sirai but I SUSPECT there are others.

What's wrong with your existing pstat? Repairable?

[timo888]

The electrical circuit of a Cremina is described in detail on Page 3 of this excellent restoration post:

http://www.home-barista.com/forum...-cremina-t464.html

The pressurestat controls the heating element directly and something like a CEME would not be a good choice in that application. The only pressurestat that I am aware of that controls the heating element directly is a Sirai but I SUSPECT there are others.

What's wrong with your existing pstat? Repairable?

Well, it is actually a convoluted story.

I managed to find an Olympia Club in disrepair, without a working pstat, among other problems. Since the pstats on the Club and Cremina looked identical to me, I was going to cannibalize the pstat from my Cremina and give it to the Club, then replace the Cremina's p-stat. But maybe I would have more options looking for a replacement for the Club directly instead of cannibalizing?

Here is how the Club was wired:



Would the Jaeger p-stat work for the Club?

I appreciate the help very much.

Regards
Timo

P.S. I filled the broken pstat with CleanCaf and let it soak, hoping that scale was simply clogging the bellows. But I would like to know what my options are for replacing it, even if it comes back to life.

[erics]

As regards the Jaegar pstat - I don't know whether it can safely and reliably handle the amperage demands/cycle demands. Someone who sells Jaegar, like Chris Coffee, would. However, admittedly taking the high road here, your best bet (and safest one) would be to replace with like kind.

Here is a good source I ran across:

http://www.olympia-express.ch/ServiceSupport.asp