Fermentation temp! Help!

Brand new to the site and first post. So this is my 6th all grain batch and I’ve had success in the past. I brewed a robust Porter yesterday and this morning it was at 62 degrees in the closet with no activity. I moved it upstairs and turned the thermostat to 70 at 6 am. I got home at 5 pm and the beer was really warm and very active. I took a sample and it was at 100 degrees! I immediately got it in an ice bath and cooled to 75 now and back in the closet. The yeast strain was wlp005.

My question is, will I have lots of esters or fusels if it was only for 10-12 hours of fermentation? Cheers

First check your thermometer. There is no way that a fermenter at 70° ambient can hit 100°. I don’t care how exothermic fermentation is, 100° isn’t happening.

You’ll never know until you taste it. Just keep the temp stable and it will be ok. Jacking with it back and forth is bad news.

You were much better off at 62 IMO.

Yeah exothermic temp swings are +/-10F no where near 30F.  Easy check is ice water should be +/-1F of 32F.  If it’s a dial thermometer you can adjust with pliers to 32F or boiling water to ~210.5-212F depending on your altitude mountains are what? 205F