Thanks to all the posts here about descaling and taking apart older MCALs, I was able to rehabilitate what I believe to be the original pstat for my 1988 MCAL. My question is this: I have the pstat set at .95 to 1.05 bar. Is it normal for these older pstats first to go to 1.5 bar when warming up and then work their way down to the set bar range around 1 bar? Thanks, Nathan

That was my experience. I don't know why it happens, though. Maybe someone seeing this can explain.

mine (not a MCal but a twin twin commercial) likes to wander up to 1.3 at first and then settles down....actually helps as it takes awhile to warm the groups

I have the same experience with a new to me 1991 Microcasa a Leva and the original pressurestat. Initial cutoff occurs at 1.4 bar and then over the next 20 minutes the machine cycles on and off at lower and lower pressures. After 20 minutes it stabilizes around 1 bar (cycling on at .85 and off at 1.0) and seems to hold this pressure indefinitely. Not sure if I am saying this correctly: The absolute value of the dead band remains the same at .15, but the activation/deactivation points shift downward over that first 20 or 30 minutes. I wait until the machine has stabilized before making any p-stat adjustments. I would also like to hear an explanation or hypothesis as to why this is happening. Perhaps the p-stat diaphragm is particularly stiff and is changing pliability with increasing temperature?

Scott

My 1985 stopped doing that after I dissassembled/cleaned/descaled the pressurestat membrane assembly (with the microswitch removed) and the sending tube. I alternated between diluted vinegar and a solution made with (powdered) dishwasher detergent for a few days until the sending tube was clear.

YMMV.

Thank you everyone, it is good to know that my elektra microcasa's pressurestat is acting normally. It's amazing how well these machines work once cleaned and properly maintained.

Over the weekend I made a new diaphragm for the p-stat using 1/32" thick, food Grade, high-temperature, 50(A) durometer, silicone rubber sheet material. Machine is now temp/pressure stable after the first off/on cycle. Dead band is < 0.15 bar. New diaphragm is much more pliable than the old, original one. I left the spring tension adjustment exactly the same, so I think the change in performance is due to the new diaphragm. P-stat tube and p-stat insides were clear.

Thanks to board member Tom@stevespresso for the tip and the bit of material he sent. This material is available from McMaster-Carr (http://www.mcmaster.com). Here's the current link http://www.mcmaster.com/#5827T21

Scott