Search found 536 matches

by jedovaty
March 17th, 2024, 2:47 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Couple more shots this morning, with 3/4 full boiler. I doubled P, but left I and D alone. Interesting result.. it didn't get to 32psi until I pulled the first shot. Then it overshot and stayed up there. {link} Figured out how to graph, too For next weekend, I am considering putting P
by jedovaty
March 3rd, 2024, 11:16 am
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Hmmmm... John and Greg, your discussion makes me hope the group gasket starts leaking soon so I can get that TC installed I reviewed last week's data with my brother who said the machine is taking a long time to actually reach the target temp so to start tuning he suggested doubling the P and
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by jedovaty
February 25th, 2024, 6:43 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Lots of reasons! A few quick ones: easier to relate to, more widely accepted terminology, helps in communication and troubleshootin, fun, challenge, why not it's just math, etc. Installing the transducer was ridiculously easy. Applying the equation wasn't difficult, either. In the end, it is kind of...
by jedovaty
February 25th, 2024, 12:29 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Greg: Exactly, that's what I discovered when the display had 212F at room temp haha. So I've changed the code to "heating" until the vac breaker locks in and pressure begins to build. John: Yup, would be nice to know, but not critical since I will have a few reference points to work off of. Remember...
by jedovaty
February 23rd, 2024, 7:45 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Greg: it's a conti prestina. I managed to get the code running last night, transducer arrived this afternoon and now it is installed. Low-temp test run to 25psi / 240F worked and has been stable now for an hour! PID might need tuning don't know yet, I, errrmm... forgot to include logging code :p. I'll
by jedovaty
February 20th, 2024, 12:24 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Haha no worries, your reputation precedes you Even with my limited experience, all the research I've done has led me to know and agree the thermocouple should be the way to go. Doing so in my case is problematic or goes down a direction I don't want to, and thus the pressure sensor route is actually
by jedovaty
February 19th, 2024, 2:50 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

The pressure sensor is at the end of a long copper tube system, so adding a thermocouple to that would require considerable snaking skill, not sure that is even possible. The junction begins at the boiler plate, goes along the face then curves down into a tee which splits into the OPV, manometer, th...
by jedovaty
February 19th, 2024, 1:11 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Because I don't know how to get a probe into the machine in an easy way, and the pressure transducer is much easier to connect.. I just replace the p-stat with this. Of course, the drawback is math and all the past two pages of junk, but hey, I'm having fun and learning, so it's worth it? Dr
by jedovaty
February 19th, 2024, 12:34 pm
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

Great, thank you! The equation then confirms the range is absolute, so I am comfortable drawing a conclusion that a 30psi device would be measuring up to about 1 bar gauge pressure. Using the table John provided earlier, shows that the boiler temp at 30psi for this gauge would be 251F/121.6C. In thi...
by jedovaty
February 19th, 2024, 11:07 am
Forum: Knockbox
Replies: 41
Views: 891

Equations and boiler pressure

This is really confusing to me, sorry to be a dunce here. From my first post, my understanding is that 0 gauge pressure is ~1 bar absolute pressure (absolute pressure == atmospheric pressure + gauge pressure). How is 0 bar gauge 0.5V and 1 bar absolute 1.1V ? Or are they saying absolute pressure