It's interesting that the discussion on the Berme REX-C100 continue on this and other threads. I've incorporated 2 in the build I just completed.
I'd started a thread complaining (apparently with a whiney tone) about the actions and representations of an eBay vendor several months ago selling these "knockoff" components. The discussion that ensued, wound up a long time forum member pretty badly. He thought I should just accept a wheelbarrow full of ineffective parts, along with insistence to "do it his way". He told me not to "spout off again". Next he demeaned my character for expecting something I'd bought to work. It went downhill from there. Kinda got under my skin enough to persist and make what I thought were two inferior products, that I initially thought were grossly misrepresented by the seller....WORK.
Well guess what? Finally completed the build. I had a whole host of little idiosyncrasies with the construction and calibration of the two cheapest PIDs in the world, but all the bugs are now worked out. The system is so much better than guess work mashing in a cooler, that it was well worth both the effort and the few bucks I saved. It also got my head into how to install and operate something I previously knew nothing about. For very little cash outlay I have infinitely improved my brew process.
First I had problems with the thermocouples. So to trouble shoot, rather than connecting them directly to the PID, I removed the crimp connectors and soldered up extension wires (an old set of stereo jacks). Good solid connections and aircraft quality heat shrink insulation covered connections. Then I ran the leads through female RCA jacks I'd epoxied through my control box wall. Finally, inside the box and onto the PIDs. Still didn't work right. I swapped TCs back and forth between units and as a last resort, switched polarity on one of the PIDs and bingo... both magically started to read ambient temp. Once I ran a test session, I found that they were within 0.5 degrees in the general vicinity of temps I expected to mash at so I didn't bother with any further calibration.
While brewing Friday, I just laid the boil PID's thermocouple on the brew stand. Didn't see the need to have it read the water temp. Boiling is boiling right? Blew right threw 100 degrees and boiled over. So I cleaned up the mess and finished the boil with propane like I'd always done. Once again buying into the prevalent theory that
you really want to be able to manually control your system and the REX just isn't good enough.
This afternoon however, I ran two test in the boil kettle. I now believe that relying on manual mode may be a crutch some folks use rather than designing a good system and LETTING THE PID WORK like it is designed to work. That is, allow it to sense the rate of change while the wort is heating up (learn your system) and make adjustments to pinpoint temperature without excess energy input that can lead to scorched wort and boil overs.
I found this fella's video (below) and will be posting a video reply to his presentation. He argues favorably for NOT NEEDING MANUAL MODE. My concern like I mentioned is scotched wort, but I ran my tests; 1) with a very small and 2) with a very large amount of water in the boil kettle. I found that with better thermal conductivity than I'd previously had (via a new thermal well in my boil kettle) that either way, nearly full or just enough water to cover the element, the REX would would adapt, approach and maintain the boil rate like mudflap72 describes in his video:
https://www.youtube.com/watch?v=zeEi1dZAovM