Feel free to file this under TLDR, no offense taken.
First off, I'd like to say I've made everything myself with hefty helpings of youtube, time and tenacity. Also, to understand my position you need to know I operate an electric, constant recirculation BIAB system. Having said that I launch into my greatest mishap yet. I made 55L of 'Dr. Smuto's Golden Ale' said to be the most brewed home-brew in Australia. My BIAB bag is ultra-fine, for a comparison makes a teabag look like expanded mesh for those in the building trade.
This particular mash schedule I experimented with a 45 deg C rest, widely recognized as unnecessary for mollified grains, which almost all from the LHBS are. Regardless I thought I'd try it for no really good reason. About 45 minutes into my mash, after i'd increased the recirc STC-1000 temp (which controls my element) to 65 deg, i opened the lid of my mash tun ( 58L keggle ) and noticed it was WAY too full. I gave it a bit- of-a stir, and realized there was a LOT less grain than I put in originally, floating about. Also, i noticed a rather off-putting unpleasant smell i hadn't experienced to date.
My first reaction was to stir the begeezus out of it, thinking the grain was somehow congealed and blocking exit from the bag. As mentioned above, there seemed to be WAY less grain than i'm very confident I put in 45 minutes or so earlier. My fears were realized when I heard a 'tssss... tsssss' sound after stirring (and reducing the recirculating flow rate). To understand my problem i have to futher explain the temperature of my element is controlled by the wort passing by the thermocouple as it flows out of the bottom of the keggle on it's way to the top. The grain had basically (nearly) liquefied, and had completely gummed up the exposed bag walls within my keggle. As no wort was being pumped through my system, the thermocouple was telling the element to heat up full bore as it was reading the ambient external temperature of about 28 deg C ( I live in the tropics, and it was winter) . Meanwhile, the element was duly responding to the instructions turning red hot in the 'open air' underneath a very full bag full of stuck wort. The 'tsss' sound referred to earlier was the sound of fresh wort dripping onto a red-hot 2500w, 240V element. Needless to say, the result was a distinct aroma of burnt wort.
After this depressing realisation, I admitted defeat and resigned myself to finishing the process. After thinking i'd possibly fixed the problem with continuous stirring I soldiered on. Sure it smelled odd, but dammit this was my brew and I was going to finish it. Despite my malodorous concoction I continued with my boil and hop schedule, naively hoping it would all just go away. In the final stages, after a bit of a challenging brew day I was waiting for the final stages of the boil, and was standing back appreciating the hard work I'd put in to date building my simple brewery. It was at this point I noticed my translucent silicon transfer tubing that was backlit by full sunlight was causing my momentary reprieve, Immediately I shaded the whole assembly, thinking... 'isn't sunlight bad for wort?' How long has it been in full sunlight? A quick calculation suggested the whole volume was exposed many times during the boil. Nevertheless I pressed on.
Unfortunately the result of nearly 90 minutes of recirculating my scorched wort in full sunlight is just about the worst beer I've ever experienced. Literally it smelled very strongly like raw sewage after fermentation. Yes, i continued to fermenting the (then) 44L of scorched, skunked wort, hoping (again naively) it would somehow fix itself with yeast. Should the same unfortunate circumstances confront you, I can advise that nothing, not time, temperature nor hops can alleviate the scorched flavor. As for the smell I have to admit one of the most disgusting [brave] things I've attempted as an adult is tasting the beer that smelled like raw sewage. Dammit I knew what I put in it, and it wasn't sewage. As it turns out, much to my relieve the smell didn't translate to the taste, which was ... refreshing. Not the actual taste mind you, just the fact that it didn't actually taste like raw sewage. Imagine if you dry hopped with 'raw sewage hops' to your beer. Aroma only.
In the end as alluded to above I tried many remedies. Over time the raw sewage smell dissipated to only the smell of walking by a water treatment plant... comparatively lovely. The beer never lost the burnt flavor though, right to the end. If I had a still I would have distilled it, but as it turned out I dumped a LOT of beer out. Also, as it turns out, you can convince yourself you meant to add the 'smoky' flavor to your golden ale, even that it's an acquired taste which, in the end, I almost appreciated. I wasn't however able to convince anybody else.