12oC great. My mistake, sorry.
Goop = stuff out of a can whether it be extract or a kit. It can be a derogatory term used by all grain snobs for pretty much anything other than all grain brews. Or it can be a term used by cheeky buggers.
As Parks highlighted, fermentation temperature is important and 28oC is far too hot for Ales (albeit a couple of exceptions).
The stc1000 is a great device and couple it with your new brewing fridge (albeit recycled from the kitchen) and this, our new brewing friend, will move you up a level.
Sorry if I sounded harsh, maybe I am being a bit too honest. The kit instructions say to brew at 22-28oC and this is complete rubbish. I got the feeling that you have been brewing according to the kit instructions and this confirms it for me. I will state this again: Following the label makes beer, doing stuff that is not on the label/directions makes great beer. Even Fermentis who make Safale American Ale dry yeast US-05, say it's fermentation temperature range is 15-24oC. Yes it could be brewed at 24oC, in theory, but for clean brewing free from off flavours you would probably want to brew in the range of 18 to 22oC at the most. I'd go as far as to say 18,19 or 20oC would be optimal for clean flavours. I am sure more experienced brewers could clarify this.
Yes starting all grain can be expensive, it depends on how complex you want the process and your equipment to be. Be careful, building up a brewing system yourself is addictive and leads to purchasing lots of expensive shiny things.
Now with your stc1000 you are on the right track. It is about time I pulled my head in and exited stage left. There is lots of useful information on this forum, have a good read. Most importantly, I hope you are soon able to fully enjoy the fruits of your all grain brewing labour.
Edit: just read you post above that you wrote whilst I was writing this. STC1000 - she'll soon be all bonza.