With my 2002 ECM Giotto I have to replace or descale the pressurestat (Ma-ter) every 6-12 months, and we have relatively soft tap water here. Our machine is on a timer and invariably I'll wake up to a loud hissing with the pressurestat stuck closed and the safety valve open.

Has anyone done a PID replacement on these machines? Yes I know it's a HX machine and don't want to debate the relative merits--I would do this for reliability first and temp control second. Plus I have a PID and SSR laying around from other projects that would work fine here.

My problem is where to put the temperature probe? And which temperature probe to use? There's no extra ports on the boiler, and it seems like i should have the thermocouple in contact with the water, not mounted on the side of the boiler case.

Another possibility that I just came across is to replace the pstat with a Sirai. I hadn't thought one would fit (my Giotto has the internal steam/water valves) but this excellent thread ECM Giotto Project has photos showing otherwise. Perhaps this is the easiest solution.

BTW, I've recently noticed some white/clearish floaty things coming out of the pump return hose back to the water tank. EEEwwww Looks to me like algae or bacteria or other such nasties. Obviously I need to disassemble and clean, but does anyone know where this stuff might be hiding? I'll start with the OPV, pump, and tubing.

Thanks...

pstat wrote:BTW, I've recently noticed some white/clearish floaty things coming out of the pump return hose back to the water tank. EEEwwww Looks to me like algae or bacteria or other such nasties. Obviously I need to disassemble and clean, but does anyone know where this stuff might be hiding? I'll start with the OPV, pump, and tubing.

If your 2002 machine used silicone water tubing, then it could be the 13-year-old tubing has degraded and you need to replace it with new tubing, so the "white/clearish floaty things" you're seeing might be small pieces of silicone.

Don't know that for sure, but I DO know that were it my machine, I'd replace all silicone tubing ASAP...

-- BR

pstat wrote:Another possibility that I just came across is to replace the pstat with a Sirai. I hadn't thought one would fit (my Giotto has the internal steam/water valves) but this excellent thread ECM Giotto Project has photos showing otherwise. Perhaps this is the easiest solution.

Note that David (cuppajoe) did have a Sirai shoehorned into his Giotto classic, but was not very happy with the too-tight fit and went with a Mater and a relay -- Relays - Magnetic vs SSRs

It is odd to me that your pStat is failing that often, and that it is stuck closed when it fails. So yours is not the typical failure of burnt contacts (which cause the machine to fail to heat.) That being the case, I think switching to a Sirai would not solve anything. Most people go with the Sirai because they have the extra contacts, and the contacts are rated for high (20 amp or 30 amp) current which pretty much solves the burnt contact issue. Sounds like your issue is different - your pStat is getting clogged, or perhaps something in the water is hard on the pStat membrane.

I don't know anything about how long silicone tubing can be used before replacing. I understand that strong acids, bases, and solvents would degrade it. I'm using the original tubing in my (also 2002) Giotto with no problems.

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I don't think I have ever seen probe in the water, maybe because it is too sensitive that way? I would look it before drilling a hole in your boiler. Looking at your boiler, in lieu of better ideas, I would get something like this http://www.auberins.com/index.php?main_ ... cts_id=211 and attach with heat sink adhesive like this http://www.amazon.com/Arctic-Alumina-Th ... k+adhesive. Need to make sure your pid supports pt100 rtd sensors and also the adhesive is rated up to 125c (1.33bar) continous, so if you set higher then may need something else.

They also make washer k-type sensors, but I didn't see anyway to attach it on yours, unless you can see a screw or something else you can put it under. http://www.thermomart.com/thermocouple- ... ture-gauge Could probably attach this type with adhesive too.

Thanks for the replies so far!

The small floaties look more "organic" than degrading tubing, but I will check it out.

Thanks for cuppajoe's Sirai post link, I had not seen that. My old commercial Rancilio had a Sirai that I was quite happy with, other than maybe a large deadband, and it never failed in 6 years of morning shots. The Ma-ter failures are definitely stuck diaphragm problems, and not current related ones. I think the Sirai is better is because the much larger diaphragm means it takes a lot more time for any crud to build up on it.

I was hoping I could retrofit a RTD/sensor from another manufacturer. E.g., chriscoffee has a few interesting sensors / thermowells from vivaldis and izzos... But I'd have to find a way to use existing ports, I don't want to drill boiler holes. I'll look into gluing an RTD onto the boiler as well.

Has anyone done this on a Giotto?

My problem is where to put the temperature probe? And which temperature probe to use? There's no extra ports on the boiler, and it seems like i should have the thermocouple in contact with the water, not mounted on the side of the boiler case.

I've studied the machine myself and a temp. sensor location is a real problem. One solution, a bit expensive, would be to replace the pressure stat switch with a pressure transducer. That could then send a signal to the PID control, resulting in tight operation. Match the transducer signal to what the PID control can handle. Pick a transducer suitable for the pressure range. You may have to put in a few loops of copper to keep it cool enough.

D.

I have similar occasional "sticking" Mater and CEME Pstats issues on my Isomac.( I have replaced them twice !)
Always stuck "on" and resets with a quick tap !
I have been advised that the easiest solution is to fit a Jaeger Pstat that is a straight replacement and much more reliable.
(Edited to correct information !)