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I've put a PID on my 2-group hx
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Conclusion
The positives.
Much easier to change boiler temperature. Just press the up or down button, vs removing the warming tray and other parts to access the pressurestat and then taking stabs in the dark as to how many turns of the screwdriver, and was it left or right?
No clicking noises. No noises at all. Totally silent.
Temperature and pressure at a glance.
Temperature and pressure held dead steady.
The PID is half the price of replacing a Sirai pressurestat.
It's fun to have and watch the display
The negatives
One hell of a lot of work. You must know what you are doing and be aware of the dangers of working with electricity and steam pressure.
Does it give you better control of temperatures?
Yes, but is that really effective? It doesn't matter for steaming milk as long as you are happy with the steam force and quantity (I was very happy). And with a pressurestat, the E-61 group does a good job of evening out and maintaining water temperature from the HX.
I would recommend getting a cheapo battery-driven digital thermometer with a thermocouple inserted into the bolt in the E61 group though --because the temperature of the water there is the rubber which hits the road.
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Another day of precision carpentry building a PID enclosure, and the final, permanent electrical wiring.
Like Goldilocks' experience, the first enclosure from old splintery plywood, I figured was not big enough and rough as...the second one way too big, and today's just right, even if the smallest.
Made from 7 mm plywood using mainly my radial arm saw, my table saw, jigsaw, multitool and assorted other tools in a time-consuming, tiring fashion. But I like the challenge.
Sprayed it grey to match the Grimac's side panels. Just have to allow the pva glue to set hard overnight before screwing in the lid.
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Thanks Mal. Much safer to solder than braze, seeing how there's no stress there.
I'm now redesigning the size of plywood project box. Once that's done and spray painted I can permanently wire up the PID and my wife can reclaim her kitchen bench and table.
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Bought some nice new plywood and I'll make another project box.
In the meantime, spent today moving a little on from the proof of concept stage to a more permanent footing.
The live leads which once attached to the pressurestat I've placed onto a terminal strip which in turn is housed neatly and safely in a little black project box screwed to the machine's robust frame.
All the wiring will be made neater, and to length, once the new project box is finished, maybe midweek.
As foreshadowed, I soldered a steel nut to a copper nut. Together they make a little tunnel into which the thermocouple screws into.
Then I syphoned out the water from the boiler via a small plastic tubing into the vacuum break valve port. The water conducts heat away during soldering.
To hold the two nuts in place during the soldering I screwed a bolt onto them and held that against the boiler with a steel rule pressing on a couple of water pipes.
Some heat transfer paste and I screwed the thermocouple into the nuts. Not too tightly as I suspect there's going to be a bit of contraction and expansion.
Fired her up, and this time the 93°c setting for 1 bar was way too cold...It's working nicely on 110° at the moment,
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Mal: "comprehending what I see isn't always what it once was..."
You're not alone in that respect!!
There are many YouTube videos about this PID, almost all used for home brewing...brewing alcohol, not coffee.
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The extra mass of the copper nut, etc won't make any measurable difference when you compare its mass with that of the boiler and water. Sorry for missing the details you posted in post#6, comprehending what I see isn't always what it once was...
Anyway, will check on the controller to become familiar with its particular idiosyncrasies for future reference.
Cheers mate,
Mal.
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Hi Mal,
The PID is an Inkbird ITC-106VH driving a 40A SSR (I gave the model details in #6)
After auto-tune-- the self learning mode-- the settings are P=50 I-30 D-8.
It seems to be working well now, but will probably need tweaking when I am satisfied of its consistency.
Then we move on to a permanent thermocouple installation to the boiler.
For that, the plan is to take the one and only copper nut I have, which is slightly oversize to the thermocouple bolt, and a steel nut I have, which is the right size and thread, and solder them together.
The copper nut is then soldered to the surface of the boiler. The TC is screwed into the assembly, add some heat transfer paste on the bead
And hopefully it all works. Having a greater thermal mass on the TC bolt will no doubt require some adjustment of the settings.
That's the plan.
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Ah, yes... Thermal Interface Compound is a given but sorry I forgot to mention it mate.
What I was actually asking re: the P.I.D. settings, is the actual individual setting of each of the Proportional, Integral and Derivative parameters. It will give us some idea of the current behaviour of the Controller/Boiler. Which Inkbird controller model have you used would help too, if known...
Mal.
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Another very frustrating day. I'll spare you the details, but wow! I had no idea silicon heat transfer paste could have such an incredible affect on a thermocouple bead.
I found a copper nut, oversize unfortunately and smeared some paste inside and around it. I had the silicon paste left over from mounting a new computer chip years ago.
I pressed the TC into the nut and both against the boiler. The thermocouple measurement shot up 30 degrees Celsius!
Experimenting with new, higher PID settings now.
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Mal, it certainly may have, especially considering it's more common for these valves to fail to seal.
Settings last night were: PID set point 60.5C. Temperature calibration offset +8 degrees.
This morning against my better judgement and proper practices I changed too many variables. I decreased the PID temperature offset by 5 degrees to bring the reading for the cold boiler in line with room temperature. This has the effect of having to heat for longer to reach set point.
I also increased the set point from 60.5 degrees to 65. This compounds the above.
So as the boiler warmed up, with many degrees still to go to set point, the pressure went above 1 bar and I switched everything off and went back to the old settings: 60.5 set point, +8 degrees C offset.
Now waiting for things to cool down before trying again.
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May have been coincidental re: the vacuum break valve.
What are your P.I.D. settings Robusto? May need tweaking...
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