I've installed in my Treviso at work pressure transducer driving SSR through voltage comparator with very small hysteresis.
It already works for 2 yrs without any visible pressure variation on the gauge.
There was blanked off connection in my machine (Treviso LX with 1,052 l boiler) next to safety valve/pressure switch combo where I could connect transducer.
If anybody is interested, I can post some photos and circuit diagram.

Thanks homeburrero!

After posting I've seen that attachement was missing,couldn't do a thing about in edit mode.

Well, hopefully it'll be done soon.2 new ma-ter xp110 pstats, safety valve and antivaacum valve are on their way.

For the moment I'll be skipping the SSR and see what happens.In case the relay on the ma-ter is going to fail quickly I'll do the SSR mod too.

Curious thing...just the other day I've found out I have two antivaac.valves on my boiler.
That nasty combo pressurestat has both safety and antivaacum valve integrated (on the horizontal stem).It seams that one of the ex-owners (I might be third or forth hand ) installed a antivaac.valve on the boiler, probably as an emergency solution.From what I recall, the fabric antivaac.valve leaks, the silicone collecting tube is usualy moistured inside.I'm far from home now to check.

I hope this is the cause of my huge difficulties in achieving quality frotations and the source of my constant frustration in this matter.

@witoldb

Any info is salutary.The SSR will probably be my next project
I've written you an e-mail months ago regarding this machine and it's frothing performance but never got a reply...maybe it got stuck in limbo

adi84g
I never got your PM.
Steaming in my machine is OK after changing to tip with 2x 1mm dia holes - I've brazed and drilled out original holes.
I think they were 1.3 mm.
My machine also has got 2 vacuum breakers - 1 on horizontal leg below pressure switch and one in the middle of boiler.
Voltage comparator circuit to drive SSR:

It might have went into your spam folder.

Thanks for the diagram.

I do not understand the reason behind the 2nd antivaacum valve.
Was your machine equiped with both from start?

I've checked the exploded diagram http://www.sanremouk.com/wp-content/upl ... Manual.pdf and there's no mentioning of antivaac.valve, neither safety valve; only pressure switch.

Adi

I bought my machine second hand and it had already both vacuum breakers.
Previous owner got it from Sanremo UK and I don't think that he did any modifications.

Is there an optimum installation postion for pstats in general? for ma-ter in particular?


What is the reason for the spiral tube to the pstat in this image?

I won't be able to replicate this but would be good to know the benefits and perhaps will succed in something like this http://coffeetime.wikidot.com/how-to-re ... ll-andreja

Offtopic: why can't I upload pics? the upper image was ok as it is a hb link.

Thanks!

That's a lot of loops! Often you see just one, and my understanding of the purpose of loops or u-shaped pigtails on the connection between a boiler and a gauge or pstat is to protect the gauge or pstat from damage by hot steam. The lower part of those loops will be filled with condensed water, and that water will moderate the temp of the vapor that reaches the gauge or pstat. Many machines don't bother with these, not sure they are that critical.

I think the ma-ter must be forgiving, as you see it mounted in your machine as well as in the Cuadra with a simple (no loops) pipe, and mounted horizontally. But I think if I were rigging a pStat connection I would use a loop or two, mount it vertically, above the water line. If space allowed, I'd place it a bit away from the boiler with room to put a Sirai.

(BTW, I understand that the loops on the capillary tubes of pressure gauges are primarily there to dampen pulses as might be produced by a vibe pump.)

I'm not a coffee machine engineer, and there are a couple people on this forum who are who might be able to support or correct my statements here.

adi84g wrote:Offtopic: why can't I upload pics? the upper image was ok as it is a hb link.

I'm pretty sure you are uploading your image but failing to click the 'place inline' button before submitting. Try editing your post and finding and using the place inline button.

Thanks homeburrero! It all makes sense.

Off: Indeed, I wasn't clicking the "place in line" button.

I managed to do the mod.

It looks like this :





The trickiest part was to connect the pressure capilary because of it's odd fitting




I've used a 3way 1/4 brass T shaped manifold
;
and all sorts of reductions, fittings and teflon tape.

This is a temporary setup until I can find someone to spiral a copper tube and have the pressure switch fitted alone.

I'm very happy with the Ma-ter xp110; now I have a .15 bar dead-band.Highest peak is set at 1.2 bars.
I also changed the antivaacum valve + installed a safety valve on the boiler.

Frothing performance has marginally increased.Pressure doesn't drop below 1.05 bar when frothing milk in a 35 cl pitcher.

I contacted the producer; they solved this issue by PID-ing the machine.This is not the way I want to go, so I'll be sticking with the pressure switch.They've endorsed me a step by step guide which I'll happily share if some Treviso owner wants to go that way.