How long should I wait before re pitching ?

I would wait a while. Give it at least a day, maybe wait til tomorrow morning and see what's happening. I can't recall having this issue with S-05 before, but who knows what can happen. How did you have the dry yeast stored? Did you rehydrate it? Just wondering, but I usually don't and it still works fine.

It's funny because the same issue happened with me on my last batch. Used WL California Ale yeast, never had a problem with it getting going over night. This time it took 1 and a half days to get going, then it was off to the races. Be patient, don't worry too much. Worst case scenario, buy another yeast pack and pitch it in the next day or 2.

 

Did you mix it in the wort, or just sprinkle it on the top?

I'd give it another day. Airlock activity is really no 100% given that it's firing away. My last batch took a day to start bubbling, and I thought I may have had a leak somewhere causing the airlock to not bubble. Opened up my bucket and it had krausen and everything, so it knows what it's doing.

Relax and have a beer.

 

I'm going to buck the conventional wisdom here (which I'm sure would be relax, don't worry etc) and suggest that you go ahead and add more SF-05 now if you have it on hand, mainly because I don't see what harm it could do and it will potentially do some good.

I agree it's unusual for SF-05 to take that long to start, particularly at that high temperature. It's possible there was something with that yeast pack. Since they're cheap, why not toss another one in there, if you have it on hand or can get it easily? I don't think it would affect the fermentation character of the finished beer, which would be minimal in an american wheat anyway. Good luck.

 

MLuxky-the harm comes from over pitching and the off flavors associated with that.

Ejayz- have you taken a gravity reading? Airlock activity is not a good indicator of fermentation. Also, it can take up to 72 hours to show signs of fermentation. Take a gravity reading and RDWDAHB

 

Just checking... you were not running the chiller inside the house? If that's the case, there's no way the temp would drop from 80 to 74-ish in 45 minutes sitting at room temp. However, 80F shouldn't have harmed the yeast from a lag time perspective.

So what happened after you added the second packet?

 

I'm only aware of two potential disadvantages of over-pitching in a homebrewing situation. One is that because there will be less lag time, you're going to get fewer of the compounds produced during the reproductive phase and thus less of a fermentation character from the yeast. Since SF-05 is a very clean yeast to begin with, and since the OP is apparently brewing an american style wheat, I assume this is not an issue in this case. The other potential disadvantage I'm aware of is that you might encounter problems clearing the beer and you might get some 'yeast bite' if the beer isn't adequately cold crashed. Since SF-05 is such an excellent floculater (is that a word? well, you know what I mean) I doubt this would be an issue, but perhaps it's worth noting that you would want to make sure to clear the beer adequately once it's fermented.

Are there other potential issues I don't know about?

 

I don't know how common/true this is, but I have heard of severe overpitching resulting in high fusel alcohols. I don't know if this was simply a matter of super-fast fermentations raising temps to fusel producing levels, or whether there is some other more 'chemical path' influence at work there.

 

From Yeast by Jamil Zainasheff and Chris White: "what are the consequences of overpitching or under pitching? In general underpitching affects flavor more, while over pitching negatively affects yeast health more over generations. However, both can result in a less than ideal fermentation with high levels of diacetyl, acetaldehyde, and low attenuation. Too high a pitching rate can also result in low or unexpected esters, yeast autolysis flavors, and poor head retention."

It might not be that much of a problem, but there are negative consequences, that's all I was getting at.