Originally Posted by nicklawmusic
It was just a dried yeast that came with the beer kit. It didn't say on it what strain of yeast it was.
The FV was at 24c for around 3 hours, after which I turned the belt off and allowed the wort to cool.
Now it's back to 20c where it should be.
Have I totally ruined my beer on that 3 hour period?
No. And I certainly didn't mean to say that in the first response to the thread. But your question was how much does it matter, and it DOES matter a lot. It'll still be beer, but I bet it won't be as good as the next one you brew when you don't bother with the belt, or turn the settings WAY down on it.
What happens is that when it turns on, the thermal inertia of the wort takes a while to heat up and then the belt shuts off when it gets to temp. But inertia doesn't stop there, the wort temp continues to rise to several degrees above the set point of the belt, and therefore overheats your wort.
In the future, if the ambient temp in your basement is a few degrees below where you want to ferment at, you can let the yeast's own heat production take care of the difference. I deal in Fahrenheit, but I'd say if you want to ferment at 65 and your ambient temp is 60, you're in a pretty good place. For finishing out really big beers after 3-4 days of fermentation are done you can start using the brewbelt to ratchet temps up gradually to the 70F+ range. The key is that fusol alcohol production generally happens in the first 72 hours of fermentation so turning up the heat for a few days after that won't hurt your beer.
Edit, it sounds like you weren't too hot for too long, so the effects could be mild. It's still beer. I personally dump batches that don't turn out right, but then again, I've brewed almost 70 batches of beer, and I brew 2-3 times a month, so I have that luxury. I wouldn't recommend dumping your first ever batch of beer unless it's completely unpalatable. You'll probably be alright, but what's been shared in this thread will help you make your next batch even better.