If the problem is really the heater then the yeast should be fine. However, just from your original post, it is not clear that the heater is the culprit. Excessive heat can cause off flavors, but to my knowledge not a sour taste. If the beer tastes sour, it seems more likely that there is an infection, in which case the yeast is unusable.
Planning: New brewery at new house!!
Primary: Barley Wine
Secondary: Red Ale, Pale Ale
Drinking: Brown Ale, 75 min. IPA, Oatmeal Stout, Poor Richard's Ale, Chocolate Cherry Stout