Diacetyl Rest with WLP 002

[PittsburghBrewer]

I'm thinking of making an ESB with WLP 002 as my first partial mash beer.

I understand that WLP 002 requires a diacetyl rest. I also understand that many people accomplish a D-rest for ales by starting fermentation in the mid-60s and letting the temperature rise to 70+ after a few days.

While less common, I've also read that an extended primary at normal fermentation temperatures can accomplish a D-rest. Does anyone have experience with the extended primary method with WLP 002 (or Wyeast 1968)?

The ambient temperature in my basement is around 65, so I'm worried about my ability to get the beer up to typical D-rest temperature. (I know that fermentation is an exothermic reaction that generates heat, but can it generate 5 degrees when active fermentation is nearing completion?)

 

[Mer-man]

It can, as it tends to flocculate before fully cleaning up after itself. That is why raising the temp for a d-rest will be used to reabsorb diacetyl.
The d-rest is the part of raising the temp -- keeping the initial fermentation period at a lower temp is to keep the yeast from going too active and flocculating prematurely. They are different actions with different functions.

You have read something incorrect, as a diacetyl rest is what I described above. The brewing term of a "rest" means a controlled duration at a specific temperature.

At 65f ambient, your beer will easily go over 70 during the first 1-2 days after the lag/propagation phase. Then it will drop after that and ferment out, probably leaving diacetyl.

To do a diacetyl rest, you have to be able to drive the temperature up for a period. Most people control the temp during active fermentation and then raise the temp after a few days. As you can imagine, that is hard to do if you cannot control the temperature in the first place.

 

[porterpounder]

A diacetyl rest is not necesssary. Yes, it may go dormant earlier than some, but swirl the fermenter a couple times a day toward the end of fermentation and let it ferment in primary for 10-14 days and you shouldn't have an issue as long as you had a healthy pitch to begin with.