Time for a new pressurestat? CEMA or MATER

Need help with equipment usage or want to share your latest discovery?
XCman
Posts: 86
Joined: 13 years ago

#1: Post by XCman »

The group on my Isomac Tea vary slowly over the last two weeks started taking longer and longer to recover between shots until it would no longer get above 187 on the Eric's thermometer. I thought I had a thermosyphon stall but have not been able to find a leak in the loop. I took apart the OPV and cleaned it, and put in a spare brew valve with new seal. Everything looks good no scale build up in the group or OPV.
Today I started looking a the front of the machine and noticed the while the the pressurestat was cycling between 1.1 and 1.2bar as I have it set for, the cycle time is only about 16 sec off and 3 or 4 sec on.
I don't remember how long the cycle times were before but this seems very fast.
Before I order a new one I thought I'd get some other opinions.

If I do need a new one, should I stay with the CEMA or go with a Mater, Jaeger or something else?

Thanks Bob.

jonny
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#2: Post by jonny »

XCman wrote:Today I started looking a the front of the machine and noticed the while the the pressurestat was cycling between 1.1 and 1.2bar as I have it set for, the cycle time is only about 16 sec off and 3 or 4 sec on.
I don't think the pstat is your problem. Faster means it's keeping a tighter temperature range. In other words, the boiler temperature won't dip too far. That's opposite of your symptoms. Have you checked for scale in your thermosiphon? I would still suspect the thermosiphon.

XCman (original poster)
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#3: Post by XCman (original poster) replying to jonny »

Jonny you the man.

I descaled the HX and she's working good as new.
I have to say that I'm a bit shocked that it was scaled up. The mushroom,brew valve and OPV were clean.
Just a vary light coating of scale on the brew valve spring. It must collect somewhere else in the group head.
Next time I'll know better. Thanks for your input.

erik82
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#4: Post by erik82 »

Just to give you an idea, my Pstat also cycles between 1.1 and 1.2 and has a cycle of 9 seconds on and 90 seconds off. Saves a lot in energy consumption.

jonny
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#5: Post by jonny »

Bob, glad to hear it's working now and that it was any easy fix! Sometimes scale can favor one metal over the other. Typically, when I've seen this happen, the mushroom is badly scaled and hardly anything on the copper. I suppose it could go the other way around too. [edit] BUT usually scale on the mushroom, means a good chance of scale in the pipes and in the boiler too. Since you had scale in your thermosiphon (copper) also check the boiler (copper) or just descale that to be safe.

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erics
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#6: Post by erics »

Before I order a new one I thought I'd get some other opinions.
That's a smart move. You did a lot of work . . . however, your quoted cycle times are most indicative of a steam leak. Here is a very representative curve:



Both of those pstat brands are fine as the Isomac has an SSR to take the brunt of the "work".
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

erik82
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#7: Post by erik82 »

Something that helped me finding leaks was to put a wrench around the parts of the boiler. Use the right sized one and because of the sealing by the wrench a leak will get less room to leak and force the pressure out on a smaller surface and is more easily heard. You don't have to loosen anything, just put it there as if you where intending to loosen it.

Had a leak once in a gasket of the boiler refill probe. Because there where 5 different things coming out of the boiler top it was really hard to find where the sound was coming from. One by one put a wrench around everything and immediately heard the sound of the hiss changing sound when I was testing the refill probe.

Hope this helps.

XCman (original poster)
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#8: Post by XCman (original poster) »

erics wrote: your quoted cycle times are most indicative of a steam leak.


Well it looks like erics was right. It took awhile to find but the wrench trick worked. (thanks for the tip erik82) The bad news is it's not a fitting. It looks like pin holes, or pin holes along a crack in the boiler where the threaded elbow fitting screws in.



I'm not sure if I can fix this or not??? It's a brass boiler so some silver solder may work. Not sure if the new stainless steel boiler will just plug in? Or what it would cost.

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erics
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#9: Post by erics »

Actually you might consider this a "blessing". Order a new heating element o-ring and other goodies that may be on your wish list. Use an electric impact wrench on the heating element (or the HVAC shop would do this for you). HVAC is Heating, Ventilation, Air Conditioning.

Disassemble the boiler completely "in place" and soak same in a very hot mix of 2 Tbl of citric acid/quart of water at least overnight, if not longer. Possibly, repeat.

Take the cleaned boiler to an HVAC shop in your area and ask them to "re-solder" the offending threaded boss.

Reassemble using Loctite 567 on all of the fittings that penetrate the boiler. Let that set overnight and then "have at it" as regards the remaining assembly.

You might want to get a few estimates as re-soldering can be tricky and a shop may give you an unrealistic estimate only because their interest is low.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

jonny
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#10: Post by jonny »

erics wrote:however, your quoted cycle times are most indicative of a steam leak.
good call, Eric! I didn't think of that.

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