A little while ago I had a woeful brew day with my exposed element crown when trying to do a stepped mash, didn't circulate the wort enough had massive caramelisation on the element. It came to the boil, I added my hops, then the boil died and it never came back up, thermostat (I assume) kept cutting it out... It was a school night and already about 11pm by this stage so I ended up draining the urn into a fermenter and sealing it up (think cubed) and filled urn with water to soak the shit off, then next day scrubbed the life out of it, put my 'cubed par boiled wort' back in and proceeded as normal... had to guess a bit as i had already done my first hop addition before the disaster. IBUs ended up OK, but the beer was shit, I think HSA was an issue perhaps transfering the beer in and out of the urn while ~95 degrees (i could of used the urn tap, but it had blocked with hop flowers!). worst brew day ever. I nearly threw the whole damn urn in the bin.