Need help debugging E61 HX machine temperature/pressure. - Page 3

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seoras (original poster)

#21: Post by seoras (original poster) »

Being suspicious of the thermosyphon, and reluctant to tear the thing apart to check both the injector (primary suspect) and restrictor, I thought I'd monitor the outlet and return (inlet) temperatures of the thermosyphon pipes.

So I attached these cheap digital thermometers (which are very accurate, I've compared them against more expensive thermometers) one to the copper pipe immediately before it enters the group head and the other at the base of the boiler where the cooled water returns back into the boiler.
It all looks ok to me and behaves as I would think a functional thermosyphon should work with a temp difference of ~10C.

I took note this time of the rebound time and it's about 1-2mins and that's not re-bounding to a temp that you'd want to pull a shot at that's re-bounding to a temp that needs a cooling flush!

Also in the picture below notice how low the boiler pressure is.

It feels like the machine's thermosyphon has too much restriction causing the re-bound to be unnecessarily fast, stable temp too high and boiler pressure too low.

Tempted now to source a replacement restrictor, drill it out to 4mm and swap it to see what happens?
If it's worse just put back the old one.


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Bluenoser

#22: Post by Bluenoser »

I think it works different than you think.. the restrictor slows down the cycling and you get a cooler group and slower rebound.

When I drilled out my restrictor a bit, it idled hotter and my rebound was faster..

The designers like Profitec/ECM and Rocket added a restrictor to keep the group cooler so it would require less flushing.. but it is at the expense of a slower rebound.

The steam boiler temp also has an effect on the group idle temp.. this is as expected.. the hotter the boiler, the hotter the group idle.
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seoras (original poster)

#23: Post by seoras (original poster) »

Bluenoser wrote:I think it works different than you think.. the restrictor slows down the cycling and you get a cooler group and slower rebound.

When I drilled out my restrictor a bit, it idled hotter and my rebound was faster..
The group head idled hotter?

If I'm understanding the restrictor (in)correctly then its position, in slowing down circulation, keeps the water in the heat exchange pipe inside the boiler for longer which increases its temp and does so quicker.
Bluenoser wrote: The designers like Profitec/ECM and Rocket added a restrictor to keep the group cooler so it would require less flushing.. but it is at the expense of a slower rebound.
That's the problem I have though. I've got the boiler set to a point where it makes enough steam (~1bar) but the temperature of the water in the HX is so high, and it rebounds so quickly, that for each shot I pull I need to flush out a cup full of hot water first.
Bluenoser wrote: The steam boiler temp also has an effect on the group idle temp.. this is as expected.. the hotter the boiler, the hotter the group idle.
Yep, that's what I'm experiencing.

With a difference of 10C/18F between HX egress/ingress that's heat I could do with losing quicker using the head as a radiator.

I think this is a fascinating topic as it might be the crux of what differentiates the many E61 machines available to choose from.
Rocket has certainly been innovative with their tilted boilers to help improve HX circulation.

I'm now making great coffees but I need to empty out 2 cups of boiling water to make my wife and myself a drink.
I can probably live with it as is but my curiosity can't leave it alone, I'd love to know more about the HX systems and how they work.
They aren't as simple as they first appear as we've all found out! :D

Bluenoser

#24: Post by Bluenoser »

seoras wrote: If I'm understanding the restrictor (in)correctly then its position, in slowing down circulation, keeps the water in the heat exchange pipe inside the boiler for longer which increases its temp and does so quicker.
I'm no expert so there is a some guesstimate.. Yes the water in the TS boiler tube (with restrictor) will get hotter .. but it won't flow fast. The E61 is like a radiator.. and I'm guessing that it will cool that TS water in no time flat without new hot water getting to it.. So we have hotter water, but less of it .. with (I think) the overall effect that the Group idles cooler with slower flowing TS. The 'Dragons" were older style without any restrictor and required *MUCH* flushing to cool. They were more aimed at commercial machines where you were pulling one shot after another and the water needed to reheat fast.

So no restrictor and there is better flow.. apparently the tube still gets the TS water hot enough to heat the group well.. and because it flows fast.. it carries the heat from the boiler quickly.. Thus, no restriction, hot group.

This is why I'm betting you have no restriction in your TS. Or one that has corroded larger than ideal.

From everything I have read in the past year or two.. restriction in TS equals cooler group, less flushing, and slower rebound. If you've been reading another thread about PID on steam boiler equalling brew water stability, there is no truth in this for traditional HX designs with a TS or TS with restrictor. (MaraX and Bezzera 13 are two different beasts here so not applicable to what I'm describing).. The PID on steam boiler only keeps that ultra stable.. there is still the thermodynamics of the TS loop and the effect of the E61 to consider. It is a totally open loop system with no real control.. sure a hotter boiler equals hotter brew water.. but it is not a precise control system. I'm finding from one Profitec Pro500 to another there is a significant difference in operation ( you can see some prior posts where I compare an exact experiment from WLL to my identical machine, using SCACE measurements and got very different results). So I'm guessing the manufacturers can't make two TS loops work identical because any small changes to pipe bends, geometry, restrictor tolerance, etc. has an effect on this perfect balance they've been trying to achieve. This is a guess.. but I haven't seen *ANY* claims of performance on their HX machines that a user could hang their hat on. The manufacturers would do better to add a $50 group thermometer and tell people exactly how an HX works, rather than tell them a Steam Boiler PID setting will magically give them 200F brew water.. Clive and WLL claim it will, because they've used a $600 SCACE to develop some workflow that gives a brew water of 200F on their one machine. If you've watched their vids, you would notice they each develop a totally different workflow. WLL sets the PID to one value with no flushes.. CLIVE sets it high with a 7 second flush.. but they could only develop those on their machines with a $600 scace for confirmation (which the normal user has no access to). So there you have 2 'expert' companies showing two totally different ways to use the same HX machine.. The answer is.. a PID on the steam boiler and a single PID setting will NOT guarantee an absolute brew water temp because TS loops are finicky and an E61 is prone to effects from the environment.. but having a thermometer on the group would allow a user to adapt their workflow for better brew water management.

A bit of a rant.. grin..

Dave

seoras (original poster)

#25: Post by seoras (original poster) »

Bluenoser wrote:I'm no expert so there is a some guesstimate.. Yes the water in the TS boiler tube (with restrictor) will get hotter .. but it won't flow fast. The E61 is like a radiator.. and I'm guessing that it will cool that TS water in no time flat without new hot water getting to it.. So we have hotter water, but less of it .. with (I think) the overall effect that the Group idles cooler with slower flowing TS. The 'Dragons" were older style without any restrictor and required *MUCH* flushing to cool. They were more aimed at commercial machines where you were pulling one shot after another and the water needed to reheat fast.

So no restrictor and there is better flow.. apparently the tube still gets the TS water hot enough to heat the group well.. and because it flows fast.. it carries the heat from the boiler quickly.. Thus, no restriction, hot group.

This is why I'm betting you have no restriction in your TS. Or one that has corroded larger than ideal.

Dave
I've just had a chat with the New Zealand service centre for San Remo and they said the same thing.
If I want it cooler with less flushing I need to make the restrictor smaller.
Something like 2mm was suggested.
Asked them if they had any 2mm restrictors and they said "no, but we experimented with cutting our own from a 10mm teflon rod".
Fun! :)

Jeff
Team HB

#26: Post by Jeff »

I was surprised the first time I looked for plastics for food-contact applications that there was a general grade and a food-contact grade. I don't know about your suppliers, but it was only a couple USD more to get the food-grade here.

Bluenoser

#27: Post by Bluenoser »

seoras wrote: Asked them if they had any 2mm restrictors and they said "no, but we experimented with cutting our own from a 10mm teflon rod".
Fun! :)
The people I've communicated with have used a metal disk and drilled a whole in the middle of it.. and somehow welded it in.. Solder might be a bad idea unless you have no-lead solder.. Lelit used to provide a number of different restrictors in their HX. You want to use something that you can enlarge.. so if you start with 2mm, you might want to eventually make it larger if that is too small.. All depends on the geometry of your TS. Mine at 2.5mm is too slow.. so I reamed it out larger..

If your current restrictor, that is supposed to be 3mm has corroded larger, or is not present, maybe you can find a replacement part? Otherwise, someone should be able to make something for you if you take them the top TS tube..

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seoras (original poster)

#28: Post by seoras (original poster) »

Bluenoser wrote: This is why I'm betting you have no restriction in your TS. Or one that has corroded larger than ideal.
i should have taken that bet! :)
Bluenoser wrote:The people I've communicated with have used a metal disk and drilled a whole in the middle of it.. and somehow welded it in.. Solder might be a bad idea unless you have no-lead solder.. Lelit used to provide a number of different restrictors in their HX. You want to use something that you can enlarge.. so if you start with 2mm, you might want to eventually make it larger if that is too small.. All depends on the geometry of your TS. Mine at 2.5mm is too slow.. so I reamed it out larger..

If your current restrictor, that is supposed to be 3mm has corroded larger, or is not present, maybe you can find a replacement part? Otherwise, someone should be able to make something for you if you take them the top TS tube..
Today I got a couple of teflon rods in the post (finally! CV19 has slowed mail to a snails pace) so I finally cracked open the TS pipe going into the E61 head.
Found the little restrictor and my 3mm drill bit fits very tightly into its hole. So that theory just got canned. :(

I'm not sure how well the teflon pipe will fit as the restrictor is tapered on both ends.
The piping I got is 10mm and 12mm but neither matches either end of the restrictor (14mm & 9mm).
Any clever ideas as to how to reduce a reducer? :)
I suspect I'm going to need to find someone with a copper/brass cutting lathe who can copy my restrictor and let me drill out 2mm, going upwards, until I hit a sweet spot.


Bluenoser

#29: Post by Bluenoser »

That's generally a nice job for a machine shop.. I'm not sure if there are different grades of brass, but use some material fit for a food grade tube. 3mm is what is in the Rocket HX, I think.. I'm surprised yours is so hot.. but I'd get 2 made.. if not too expensive and as you say.. start with about 2mm.. maybe get the second (if you do 2) at 1.5mm..

seoras (original poster)

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

There's another, potential, option. I suspect that Sanremo has used 3rd party parts OEM-ed.
I know from my previous 1990's Sanremo HX that it used Wega parts.
The steam wand on my current machine is also on Astoria Cma, Wega, Ascaso, etc.
The E61 group head is just an off the shelf standard head.
The PID is also used in the Quick Mill.
That's something that Rocket doesn't do, they have their very own unique HX boiler design which is probably why their's works so well (at least domestically).

I'd love to find out what other manufacturer's machines have the same 1.8L boiler mine has and if they all use the same restrictor or not?
Tricky, but probably worth spending time on.