Fry bacon, and drain fat from skillet. Return 4 tablespoon fat to skillet, and add celery, onions, flour, and salt. Cook gently. Add sugar, vinegar, and water. Bring to a boil. Put bacon on top of potatoes. Pour sauce over potatoes and bacon. Bake in the oven at 350 degrees for 30 minutes or put in a crock-pot until well heated.