In your particular machine, the pressurestat should last a long, long time BECAUSE all it does is switch a SSR (solid state relay) which sends power to the heating element.

TYPICALLY SSR's fail with the power contacts in a closed position (or so I've read) and whether or not a SSR can intermittently fail is beyond me. In any case, I would think seriously about replacing your existing SSR with a new one - see Chris' Coffee website.

How is your water treatment? I've seen at least one (extreme) instance of the copper line to the pressurestat clogged with scale.

I had the safety valve blow on my Anita (very similar to Andreja) , and it was as Eric said an SSR failure rather than a pressure stat. If you are interested in trying to replace the SSR, this should be the correct part http://www.newark.com/crouzet-ssr/84137 ... nsku=false

Maybe your SSR is drawing too much current and causing premature pstat failure?

I did a whole bunch of work on the setup this weekend. Rebuilt the E61, did another descale in the old pstat, replaced the expansion seat valve, and replaced grinder burrs in my Vario.

Afterwards the pstat was working but was still inconsistent both in where the limits were and the range so I replaced it with a new Ma-ter pstat (old one was a C.E.M.E.) that I ordered back when the pstat first started misbehaving.

Machine now runs nicely and the p-stat range is tighter than before (<.3 bar).

I've still got another problem with brew pressure but I'll start a new thread for that.

drgary wrote:I would descale a pressurestat with 50/50 white vinegar/water instead of citric acid.

Thanks for the tip. I'll do that next time!

Headala wrote:How is your water treatment? I've seen at least one (extreme) instance of the copper line to the pressurestat clogged with scale.

I just get water out of the tap and descale every few months.
I've been wondering about filling the boiler with a mix of distilled water and then running shots with tap water.

erics wrote:TYPICALLY SSR's fail with the power contacts in a closed position (or so I've read) and whether or not a SSR can intermittently fail is beyond me. In any case, I would think seriously about replacing your existing SSR with a new one - see Chris' Coffee website.

Thanks! I'll keep that in mind for my next parts order.

For the record:

- replacement p-stat started going again last week. I've been able to avoid blowouts by turning it on, letting come to temp, pulling shots, and shutting it back off again soonish.

- turns out I have a Finder relay. I still haven't checked p-stat ratings per AssafL's suggestion.

ChrisCoffee suggested switching back to a CEME p-stat, so one is on order. We'll see if it lasts longer than 11 months.

Assuming you have observed the pressure ramping up until the OPV opens? Or could you have a faulty OPV on the boiler and it is opening at low pressure.

The pressurestat on your machine should last a LONG TIME. My preference is the MA-TER because of its ease of adjustment and relatively small deadband. The pressurestat simply controls a SSR (solid state relay) which, in turn. controls the on/off to the heating element.

I do not have enough knowledge to know if an SSR can be intermittently "bad" (unusual?) but . . .

An SSR can fail by degrees depending on ambient temperature. In simple terms it does not go all the way to an open circuit, jut a relatively high resistance. Most pressurestats are rated for 20 or 30 amps 240/120vAC so in most cases a SSR is not required

OK, blowouts have started again. CEME lasted 5 months.
It's still in the phase where it doesn't cause overpressure blowouts until the machine has been on for over an hour or so.

Chris Coffee didn't suggest replacing the Finder SSR last time, but I'm getting more suspicious of it, or maybe the wiring generally. That said, replacing the pstat does get things working again for a time.

Is there any way a SSR could degrade in a way that:
a) replacing the p-stat would make the SSR happy enough for a time before it started misbehaving again?
or
b) it causes premature wear on the pstat?

Whatever is wrong, it has been wrong for over 5 years in this machine.