Need help debugging E61 HX machine temperature/pressure. - Page 4

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#31: Post by Bluenoser »

Looks like that 'dark brown' bit on top could be replaced during manufacturer.. Not sure if it is metal or how hard it is to replace.. but I'd be temped to take that off and have someone weld on a solid brass disk overtop..

My Profitec HX has a 2L boiler and uses a 2.5mm but has very slow rebound.. I think there are a whole bunch of factors in the TS design that effects its effectiveness.. Grin.. you are going down the HX rabbit hole.. Next you'll need to find the relationship between your thermometer and the actual screen exit water. I borrowed a SCACE to find out that on mine.. but you can also build a makeshift one..

Good luck..

seoras (original poster)

#32: Post by seoras (original poster) » replying to Bluenoser »

The 'dark brown' is just dirt on the metal. It's all brass, or copper, metal. Nice and heavy.
I thought about soldering on something but I'm making decent coffees so I don't want to lose the good base I have by being heavy handed in my experimentation. EDIT - Afterthought; isn't solder lead based? You really don't want lead in your water piping for the sake of your health!
As for true temp at the head I've figured out, by taste, where the sweet spot is on my "Eric's Thermo" that's fitted. 88C-89C on it and the brew is good.
I could buy one of these from the parts dealer in Auckland if I really wanted an accurate measurement.

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seoras (original poster)

#33: Post by seoras (original poster) »

I've been mulling over how to proceed with my quest to get the Sanremo Treviso to play nice with temperature.
To summarise, the restrictor was present and its hole was the factory diameter of 3mm.
I've not sought out a machine shop yet to get a new one cut and I'm certainly not putting lead solder on something that water I drink passes over/through.
So I had an idea yesterday to use copper wire.
A bit of simple maths; A 3mm hole has an area of 7.07mm2
I have a piece of copper wire 1.6mm in diameter. cross section area would be 2.01mm2
Placing the wire inside the hole of the restrictor leaves an area of 5.06mm2 which is equivalent to a hole size of 2.5mm2.
To keep the wire in place I just bent over the ends and folded them in. (see photo below)

Now instead of the machine taking only 10-15mins to warm up to a usable temp it takes 25-30mins.
Not a problem for me, I'm happy to wait. This might be the reason though that the restrictor hole is too large. Faster warm up time.
Now, however, I can pull a really good shot with NO PRE FLUSHING! Success!! :D
Temp sits in the 90-95C range instead of sky rocketing to 95-100C.

EDIT - forgot to say that re-bound is fine. Not much different from what it was before.
I tend to steam after pulling the shot and by the time I'm ready to make the next shot the temp is back where I need it.

I'm going to play with the boiler temp again to see if I can tweak it further.
Now that I have working prototype I'm going to look for a machine shop to cut a new brass restrictor with a hole of 2.5mm

seoras (original poster)

#34: Post by seoras (original poster) »

I thought I'd give an update here on how I'm progressing my improvement works on the Sanremo Treviso LX.
From the endless google searching I've done it is frustrating just how little information there is to be found about this machine out there.
So I'm doing these followups so that there is a referenceable record of what I've attempted and learned for anyone else who comes looking.

It's been just over 3 months now since I fitted the thermosyphon valve with a copper wire hack to reduce the flow rate.
I estimated that I'd reduced it from the factory 3.0mm to approx 2.5mm.
The machine was very fast at heating up (20mins) and rebounding but with my wire hack in place it took longer to heat up (30mins) but kept a good rebound.
I sourced a company that supplies parts for my Treviso and ordered a spare valve from them which took a few months to arrive.

Somewhere back in this thread someone speculated, due to the different colours on the valve that I removed and photographed, that it was made up of different metal layers. It isn't. It looks like it is solid brass from the replacement part I recently received.

I then did a SOS call for help locally for someone who had brass machining skills to copy the new valve and found a retired pilot who very kindly offered to mill another one with a smaller hole of 2.5mm.

I fitted the new, machined, valve with the 2.5mm hole yesterday and the results are very interesting.
The machine now heats up just as quickly as it did with the 3.0mm hole which is surprising because the quality of the coffee is better than it is with the 3.0mm hole.
So I'm left wondering why Sanremo didn't ship it with a 2.5mm hole, or smaller? I had assumed that warm up time was a factor.

The coffee quality isn't as smooth as the wired hack valve version though so I've asked my new friend to make me another one and make it 2.0mm.
I'm nit picking a bit on flavour, I had a very decent coffee this morning and so did my wife. I know it can be better though.

We can always drill upwards from 2.0mm if need be and I'm kicking myself for not having started there in the first place.
I'll post another update when I try the 2.0mm valve.

seoras (original poster)

#35: Post by seoras (original poster) »

This will probably be my last post on this thread that I started because I'm pleased to say I might finally have reached a point of as perfect an espresso shot as is possible on the Sanremo Treviso LX.

I swapped out the restrictor valve with the wire in it for a 2.5mm one. It was good but not as good as the "wire hack" version.
So I had a 2.0mm valve made and fitted it at the start of the week.
The reasoning for going down to such a small size being that we could drill the hole larger and work our way up.

The machine took nearly twice as long to warm up and the peak temp that my "Erics Thermometer" read at the head wasn't very high. 92C at most.
So it looked like a thermosyphon stall which was expected - but we had to try just to be sure!

I didn't want to go up in increments of 0.1mm between 2.0 and 2.5mm because the guy who cut me the new restrictors (he made 4 in total!) did it all for free which was very kind of him and not unusual in New Zealand. Didn't want to abuse his kindness.
Lovely people Kiwi's. So pleased I moved here (for a number of reasons!).

I went back to looking at the surface area of the holes at each diameter and created a small spreadsheet. (see below)

As you can see if you approach this in terms of hole area it probably makes more sense to make incremental changes in 1mm square steps.
e.g 3.0mm is ~7mm2, 2.5mm is 5mm2, 2.0mm is 3mm2 etc...
So 4mm2 was the next point to test.

I asked him to re-drill to 2.3mm as I felt it was better to err on the cautious side.

The 2.3mm restrictor is slightly slower at warming up (~25-30mins) than the 2.5mm (20-25mins) one but the flavour has no hint of harsh burnt bitterness which the 2.5mm had just small amount of.
Rebound is excellent.

I've create a facebook page named "Sanremo Treviso Espresso Machine Owners" for anyone who wants to discuss this machine further.
To those who replied to me, thanks for the advice and pointing me in the right direction in fixing this machine!

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#36: Post by Bluenoser »

While the 2.3mm might seem the best.. you also need to balance your 'rebound time'. This drives me nuts on my Pro500 with a 2.5mm restrictor.. I can get a decent idle temp (200F), but after I pull a shot, the characteristic is that the TS water will drop temp over 3 minutes and bottom out 5F cooler.. So in 3 min. It is at 195F.. I can pull at this temp, but 3 min later it is now at 190F and I need to wait over 10 minutes to get back to 200F.. If I'm making 3-4 shots, it is maddening. (And also every shot has a 5 degree different brew water extraction). Although my Eric thermometer is right at the water inlet point of the group, I have found it is a pretty exact indicator of what my brew water will be as long as the group is stable, or heating up. This slow reheat also makes it impossible to dial in a bean based on temp as you can't do multiple shots at the same temperature. (Maybe if you had the patience of Job..)

If you find your 2.3 also has a slow rebound, then you might want to go larger (2.7mm) and just control the brew water temp by a short flush before you pull. (Your bitterness, is likely just the brew water too hot.. the flush will bring that down). I've also used a foam sponge with cold water to cool the group.. and others have used a fan flowing across it. This will cool the water in the TS, allow you to pull a shot, and then your rebound might be faster.. Now you won't need to do all this if you rebound at 2.3 is okay.. that is just the problem with my machine (and I assume some other HX models)

All these HXs have slightly different characteristics.. I think it has a lot to do with the volume of the TS, the geometry of the piping, etc. And so, being new to this hobby, drove me nuts for about a year. I learned a lot about machines.. but an HX is not an easy machine to start on.

seoras (original poster)

#37: Post by seoras (original poster) »

Hi Bluenoser,

The rebound is excellent. I can't tell the difference between the rebound of 2.5mm and 2.3mm but I can tell the difference in taste.
Just had today's coffee which is the 2nd day using 2.3mm and it's the best coffee I've ever made at home.
So I'm delighted with the consistency so far.
My rebound time is effectively how long it takes me to froth milk, grind and tamp for my next shot.
In fact it takes less time than that because my Eric's Thermometer shows the head slightly higher when I start the 2nd shot.
I usually wait for the ET to show 90C then pull the first shot which peaks to 95C and flat lines around 93C. 2nd shot starts about 91C, peaks at 96C and flat lines around 94C.
So it's a good rebound for making back to back shots.
Yesterday I let it idle for an hour just to see how hot it got, did a cooling flush and all seems to work well with just leaving it on for long periods.

You are right about all these HXs having slightly different characteristics.
Mine has a 1.8L boiler, an early model PID (designed mid 00's I'd think) and a 1500W element.
I keep the PID temp at 118C (it measures boiler surface temp, not internal water temp). The NZ distributor told me they set them to 116C.
At 118C though the boiler pressure gauge sits around 1Bar +/- 0.2 which I've notice is the pressure you usually see on HX machines.
There has to be a balance between good steam pressure and water temp affecting flavour.
I think I've got the right balance now for my machine.

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#38: Post by Bluenoser »

That sounds excellent... After having an HX for a while, I think you need to tinker, as you have done, with each thermosiphon restrictor to find one that works well in a particular machine (even identical models will have slightly different characteristics.. and as you found, your 2.3 works light-years better than the 3mm you had) .. Your hard work has paid off!..

I'm guessing you'll drop a few degrees from the Eric reading to the brew water (generally true if temp reading is stable or rising), so what your Erics reads before the shot is likely close to your brew water temp.. From what you are describing in temps.. it seems very consistent... That peak at the beginning in normal in all HX shots.. the peak is 'sucked' up by the E61.. which evens out the brew water temp..

As an aside.. got into this hobby after visiting my sister in Auckland.. was there a month several years ago.. toured all around north island.. and introduced to the "flat white".. Think I drank 2 a day.. amazing cafes all over the island... the addiction took hold.... ..

seoras (original poster)

#39: Post by seoras (original poster) »

Bluenoser wrote: As an aside.. got into this hobby after visiting my sister in Auckland.. was there a month several years ago.. toured all around north island.. and introduced to the "flat white".. Think I drank 2 a day.. amazing cafes all over the island... the addiction took hold.... ..
I'm not from New Zealand originally, I moved to NZ from Scotland with my Kiwi wife and kids several years ago.
I brought my coffee machine and addiction with me and this country just made it a whole lot worse! :)
It's very much a coffee and cafe culture which is a bit different from the pub culture I left behind in Scotland.
The coffee roasters I use, Rocket of Hamilton (no connection to Rocket of Italy the machine manufacturer other than they are also owned/run by a Kiwi) make the best coffee I've tasted on the planet. I'd love to find a coffee roaster who can surpass them.

Anyway the main reason I'm following up is that I was digging through emails I'd exchanged with the Sanremo distributor and service agent in Auckland back in December and found this interesting comment in one of the replies I got from them which I'd completely forgotten about:
The 3mm restrictor is actually really large compared to a commercial machine(2-2.5mm).
I would assume this is to balance the smaller boiler and thermal syphon volume.
I would think that the machine is designed to be flushed before brewing coffee or else the brew water would be far to hot for ideal espresso.
With a 3mm thermal syphon restrictor it wouldn't take long for the loop to get beyond 92c.
Interesting eh?
We can only guess at why...