How long should a pressurestat last?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
acodring
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#1: Post by acodring »

Hi there,
I bought a used Quick Mill Andreja about 5 years ago. It is a 2004 model that I understand was 'modded' at Chris Coffee with many of the Andreja Premium features. Over the years I've replaced a bunch of parts and rebuilt the group. Of all the work I've had to do to keep it running happily most seems like normal wear and aging. I've been pretty good at weekly cleaning and quarterly light descales.

The one thing that seems to fail more often than I'd expect is the pressure stat (p-stat). They seem to last about a year before we get woken up by the tell tale morning explosion of the pressure relief valve. It's a rough way to start the day and the cats really don't like it. It's just happened again this week.

I've had CEME, Mater (maeter?), and Jaeger installed. I paid extra for the Jaeger thinking if it costs twice as much it'd last but it failed after a month.

This year I've been reducing the 'on time' for the machine to reduce the p-stat on/off cycles. For the first few years the power outlet timer was set to about 6 hours per day, now it's down to 3 hours per day.

I'll order another pstat but I'm wondering if a year is a normal lifetime for a new p-stat. I'm also wondering if there's anything I can do to extend their life.

Thanks for any advice.

Cheers,
Andrew

Sgt.Coffee
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#2: Post by Sgt.Coffee »

That does seem very short, especially as you've tried several brands - I would consider whether it's another component at fault.

Obvious question first, how high is the safety relief valve set, is it significantly over the p-stat setting?

acodring (original poster)
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#3: Post by acodring (original poster) »

I would consider whether it's another component at fault.
Agreed, but I don't know enough to guess which. The problem is definitely fixed for a year or so when I replace the p-stat though. It there some other part that could be causing early failure of the p-stat?
Obvious question first, how high is the safety relief valve set, is it significantly over the p-stat setting?
Safety valve blows at over 2 bar. P-stat range while it was working was ~.9 to 1.3.

I removed the p-stat yesterday and turned it upside down to fill it with citric acid and let it soak for the day. It's back in place now and I'm doing a carefully observed full machine descale. The p-stat has cycled properly a few times, but I'm not confident enough with it to leave it unattended yet. The range today isn't super consistent but the last cycle I took numbers for was ~1.2 to 1.7 bar.

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bill
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#4: Post by bill »

Have you checked the pressurestat contacts to be sure they haven't fused shut?
Bill
LMWDP #43

I wasn't born in Texas, but got here as fast as I could!

Nunas
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#5: Post by Nunas »

Good question. I can think of two possible issues. One is the quality of the stat, the other is the placement. In the original Magister Stella, the pressure stat (probably a Mater) is small and mounted near the boiler. In the Pro model, a much more robust looking stat (probably a Sirai) is fitted and it is remotely mounted via a much longer copper pipe, well away from the boiler. Getting the stat away from the heat and steam is probably is a good thing...can't hurt anyway.

acodring (original poster)
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#6: Post by acodring (original poster) »

bill wrote:Have you checked the pressurestat contacts to be sure they haven't fused shut?
Do you mean contacts inside the housing of the p-stat?
I haven't gone as far as cracking it open yet.

Could that really be the problem if it mostly cycles OK after the internal descale?
Sure the range is inconsistent but it is turning the boiler on and off.

acodring (original poster)
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#7: Post by acodring (original poster) »

Nunas wrote:Good question. I can think of two possible issues. One is the quality of the stat, the other is the placement.
On the quality, I'm now wondering if age is a factor. I looked more closely at the specs stamped on the side of the CEME.
There's a datestamp - 03/11/05. I don't know which countries use which date formats, but there's a 66% chance this p-stat was over 10 years old before I installed it...
In the original Magister Stella, the pressure stat (probably a Mater) is small and mounted near the boiler. In the Pro model, a much more robust looking stat (probably a Sirai) is fitted and it is remotely mounted via a much longer copper pipe, well away from the boiler. Getting the stat away from the heat and steam is probably is a good thing...can't hurt anyway.
That's an interesting idea. I'll see if I can install it a little further away from the boiler. It's snuggled right up beside the insulation now.

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bill
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#8: Post by bill »

acodring wrote:Do you mean contacts inside the housing of the p-stat?
I haven't gone as far as cracking it open yet.

Could that really be the problem if it mostly cycles OK after the internal descale?
Sure the range is inconsistent but it is turning the boiler on and off.
You could check the contacts with an ohmmeter to see if they're stuck closed, but you're right. My experience is that once they fuse shut they stay shut. I'm not familiar with your machine, but if you have the room a Sirai would be the way to go.
Bill
LMWDP #43

I wasn't born in Texas, but got here as fast as I could!

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bill
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#9: Post by bill »

Nunas wrote:Good question. I can think of two possible issues. One is the quality of the stat, the other is the placement. Getting the stat away from the heat and steam is probably is a good thing...can't hurt anyway.
I agree! Heat from the boiler may be your problem.
Bill
LMWDP #43

I wasn't born in Texas, but got here as fast as I could!

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AssafL
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#10: Post by AssafL »

There was one thread about a machine that was clumsily reconfigured for 110v with inadquately rated components. (Edit: it was done so by the manufacturer no less...., the IEC connector melted...).

If in 110v location, check the wattage and the rating on the Pstat. Many of these are rated for 9amp so for 110v that is less than 1000 watts.

If that is the situation you can add a relay to take the wear off the -
Scraping away (slowly) at the tyranny of biases and dogma.

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