Slow/stuck fermentation

My last 3 beers have crapped out at around 1.020, when they should have been closer to 1.008-1.011. I've used 1L starters on all of them and on the last two batches I even stepped up the starter for a higher cell count. One time it happened when the batch was in my chest freezer with dual temp control, the other three times the batches were in a heated room and the fermometers showed 66*F. Any ideas on what could be causing this?

The floor in the family room by the garage door is cold and could have caused the yeast to drop out, but what about the chest freezer? Does the freezer cool from the bottom and could it have caused the yeast to drop? (We also use wood heat and it is possible that the room temp dropped overnight.)

(I've been brewing for 13 years, all-grain for the last three. I brew 2-3 batches per month and this is the first this has happened.)

 

Forgot to add that for the last year my schedule has been: 1 week in primary, 1 week in secondary to clear and/or dry-hop, 1 week in keg carbonating and drink. This has worked for me no-problem and has given me plenty of excellent beer. We've been having monthly parties and this turn around time has been quite successful in satisfying my "customers".

 

bad thermometer affecting your mash temps?

 

Extract in the recipe? Mashing too high? Also, only 1 week in primary? I don't even look at my beers until they've been in primary for 3 weeks.

 

Recently calibrated my thermometers.

Roused the yeast last night and everything kicked into gear again. Lots of action through the blow-offs/air-locks.

With proper pitch rates and correct temps I've pretty much always been successful with one week in the primary with normal gravity beers.

 

Thoughts on my attempt? Using a stir plate.

Stuck fermentation as well.
All grain
12 lbs pils 2row
1 lb vienna
1 lb munich
1 liter starter pitched belgian saison Ale

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