Posted Mon Jan 7, 2013, 4:51pm Subject: Re: Automation of HX cooling flush?
I might have failed to mention that this idea was for home use. While HX's are designed to work at a commercial pace my home pace is quite a bit slower and I just wanted to add accuracy to the flush.
I gave up on the idea of the PID control of the boiler temp and took the sensor out of the boiler. This machine is pretty new, pressurestat still keeps it in a really tight band.
I ended up installing the sensor at the top of the boiler HX outlet (see pic) and it's 100cm long so it's pretty much sitting in the middle of the HX. Interesting results watching how the temp fluctuates inside the HX depending on the parameters I set. I also have to think of a way to work this extra parameter into the algorithm in a useful way, as it seems to be an indication of the temp that will eventually make it's way to the grouphead.
I've been playing with the PID algorithms and I've got it working pretty good. Takes a little more water and more time than a manual flush but I think it likely makes for a more stable temp.
I really have to take some pictures or video and post some data logs...
StuLouden Senior Member Joined: 6 Feb 2013 Posts: 1 Location: Avon Lake, OH Expertise: I live coffee
Espresso: Nuova Simonelli Appia 1 gr... Grinder: Nuova Simonelli MDX
Posted Wed Feb 6, 2013, 3:35pm Subject: Re: Automation of HX cooling flush?
Well I'm happy to have come across this thread... I too have an Appia 1 gr Vol. and recently been thinking along the lines of what you are doing.
I'm curious to see the data you get from the HX... I'm looking to get a Extech EA15 dual input data logging thermometer to record extraction temps and measure flush techniques to achieve optimal temp for brewing.
Keep up us in the loop, I'm excited to see what you develop.
Posted Wed Feb 13, 2013, 10:31am Subject: Re: Automation of HX cooling flush?
Constructed another version of my circuit board with 4 RTD input channels. Put another sensor in the grouphead after the solenoid to see how much the temps differ after the hot and cold sides mix on their way to the portafilter. Wish I had a scace thermofilter handy to see how temp at the puck corresponds.
Got the control panel and display pretty much how I want it (turns out there's a cutout in the appia's front panel that looks like it's for an lcd, just had to cut the front). Just want to work on what and how I'm displaying the data. I actually found a better set of stick on buttons that I ordered from China, might take a while to get here with Chinese New Year's.
I've ordered some aurelia gicleurs to play around with the thermosyphon flow and see how I can tweak the temps (inspired from the recent Oscar/Musica restrictor activity).
Is it insanity to take a knife to the front of a perfectly good commercial machine or is it geekdom? ;)
Coffeenoobie Senior Member Joined: 11 Dec 2011 Posts: 3,070 Location: PNW Expertise: I like coffee
Espresso: N S Oscar Grinder: K30 & Vario W
Posted Wed Feb 13, 2013, 4:55pm Subject: Re: Automation of HX cooling flush?
It is the same head as Musica and I saw the group head drilled for a probe on Musica. Plindy said there looked like there was a spot for it to be drilled but I don't see where that is. You can look at the photos of mine.
Posted Thu Feb 14, 2013, 8:28am Subject: Re: Automation of HX cooling flush?
Hmm... looking at the pics you took and the diagrams of the grouphead I wonder if you could tee off the expansion valve and put a sensor in there. Don't know the measurement on the expansion valve or if there's be enough inside diameter inside a tee of that size to accommodate a threaded sensor... but I thought I'd throw the idea out.
If it's a 1/4" thread I'd say it might be possible and from the pics I'd guess it is.
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