Wl802 Czech Pilsner Yeast- How Hot Is Too Hot?

[barto1308]

I decided to whack out a czech pilsner the other day, and picked up a vial of WL802 pilsner yeast. The vial was an 09 batch, but my LHBS reckoned it would be fine. SO I pitched it in a 1L starter and went about my mash and boil. When I came back to the jug of starter, there was absolutely no activity to be seen- not even a few little bubbles. The yeast was pitched on the starter at about 20C, and that temp remained fairly constant due to ambient temp and humidity here in Canberra. As I was no chilling, I left the starter on the shelf in the brew room and decided to wait until this morning to pitch it on the wort. Again this morning, no activity in the starter. It has been warm and humid here - about 25-29C, but ambient in the garage overnight should have dropped down below 20C. I have decided to sacrifice the half keg of Golden ale in my only temp controlled fridge, which is now set to a decent lager temp of 15C and placed the fermenter in there to at least let it ferment at the right temp, or close to.
If I get home from work today and still see no activity, should I be concerned? Have I fried the yeast at the temps previously mentioned? I have some 34/70 which I could spike it with if I see nothing for a few days, but I would like my purpose bought yeast to work, and I would like to harvest it pure for some future brews...

Any advice out there?

 

[felten]

Lager yeasts don't enjoy higher temps the same way that ale yeasts do, but I don't think you would have cooked them at those temps. I would think either, A) you missed what little action there would have been, or B) the vial is so old that the yeast are dead/in such small numbers you wouldn't have seen any activity.

By 09 I'm assuming you mean 2009? If so that is very old for a liquid yeast package (especially if stored improperly), put the information into the pitching rate calculator and see what it says.

Is there a white layer settled on the bottom of the container? That is a good sign the yeast has done something.